2.1 Preliminaries

One of the most striking and, for some readers at least, perhaps even disconcerting features of the guarantee addendum and, in particular, the guarantee footnote (TPP 8: 361.5–362.39), is the presence and indeed prevalence of concepts prominent in scholastic (especially early modern scholastic) philosophy, such as “providence” and concursus relating to God’s causal role with regard to events in space and time. Moreover, and as we shall see in detail below, Kant clearly commits himself to finely tuned positions that endorse such a role. This seems to fly in the face of the results of his project of a critique of pure reason, one of which is that knowledge of objects is restricted to the realm on this side of the bounds of sense. While it is contentious as to whether Kant’s transcendental idealism is itself a form of metaphysics, it is clear that he denies the possibility of knowledge of objects beyond the bounds of sense, that is, the feasibility of transcendent metaphysics as a theoretical science. However, this does not preclude the pertinent claims he makes in the guarantee addendum from having a different function.

Kant takes the existence of God as well as God’s objective ultimate end as given throughout these passages and this can give us a decisive hint. In Kant’s œuvre, it is the task of the so-called moral argumentFootnote ¹¹ to back up these claims, and there is no indication that he is departing from or revoking this strategy here. In addition to this, the moral argument is supposed to be able to give us a determinate concept of God. In the relevant passages of the Critiques, Kant only mentions the traditional theist predicates contained in this concept, but the apparently foreign and unfitting considerations in the guarantee addendum can best be regarded as going into much more detail for the purpose of conceptual clarification. The question then is: What should we make of the very theses about, for example, God’s role with regard to events in space and time? In the light of what has been said about the moral argument, one plausible suggestion is to treat these theses as corollaries of taking God – on practical grounds – to be a perfect rational agent equipped with traditional theist properties, while at the same time upholding the results established in Kant’s transcendental philosophy – for example, the validity of the principles of the understanding, such as the second analogy of experience, and the methodological naturalism that comes along with them. We shall see how far we can get with this idea in the discussion of the guarantee addendum.

In the literature, the term “practico-dogmatic metaphysics”Footnote ¹² has been suggested to cover the set of such claims about transcendent objects – for example, in our case, the perplexing thesis that we may consider God to be the sufficient cause of natural events in the world (TPP 8: 362. 26–28fn). Since “dogmatic” has the air of the illegitimate (although Kant himself sometimes uses this term in a much more neutral sense, and this even in TPP 8: 362.10), one might wish to consider using “practico-transcendent metaphysics” or “practically grounded metaphysics” instead. The term “practical” is in any case more suitable than “moral” in order to distinguish this set of claims from Kant’s metaphysics of morals which is concerned with normative issues.

In the following, I will use the phrase “practically grounded metaphysics” in order to emphasize its peculiar epistemic status. As we shall see in section 3, Kant’s investigations about transcendental freedom (which, according to him, we are committed to by virtue of the categorical imperative) can plausibly also be read as belonging to such a practically grounded metaphysics. The same is true for at least some of his doctrines regarding the compatibility of transcendental freedom and natural causal determinism. Hence, “practically grounded metaphysics” – in my opinion – has at least what we can call a theist, a libertarian and something like a compatibilist dimension, thereby ensuring that the first two dimensions are both mutually coherent and coherent with the results of Kant’s theoretical philosophy, in particular the transcendental account of experience. As I shall point out, part of the difficulty with understanding the guarantee addendum is due to the fact that in these passages Kant is only dealing with the theist segment of this type of metaphysics and its coherence with the transcendental approach. For the other dimensions we need to draw on different material in Kant’s œuvre.

2.2 The Guarantor Powers

We can now turn to the text of the guarantee addendum. This section (TPP 8: 360.10–368.20) is divided into the main text consisting of eight unnumbered paragraphs and four footnotes, the first of which extends over no less than five pages in the second, pertinent edition of Perpetual Peace and deserves our particular attention, although, of course, not just for this reason. The main text starts off with an introductory paragraph elucidating the relationship between nature, fate and providence and their role as the guarantor of perpetual peace. It is here that Kant also recommends focusing on nature when it comes to theory as opposed to religion, and it is fair to say that the main treatment of providence is delegated (which by no means suggests “relegated”) to the huge footnote. The key passageFootnote ¹³ in this first paragraph of the main text, cast in a sentence of stunning syntactic complexity even according to the demanding standards of Kant’s notoriously hypotactic prose, reads as below. I shall start with the German original and then try to provide a translation that is as literal as possible.

The translation is as follows:

Strikingly, Kant calls the guarantor power “nature”,Footnote ¹⁵ but at the same time provides two alternative labels for it, namely “fate”Footnote ¹⁶ and “providence”.Footnote ¹⁷ Moreover, there are two possible ways of reading the syntax of the sentence quoted above. On the first reading, the relative clause beginning in the second line of the quotation (i.e., “aus deren … ” [“in whose … ”]) is elliptical with Kant leaving out a relative pronoun “die” (“which”) in the fourth line before “darum” (“therefore”). This pronoun, had it been there, would have to refer to “Natur” (“nature”). On the second reading, the relative clause starting immediately after the demonstrative pronoun “das” (“that”) at the very beginning of the quotation is “was … leistet … und … genannt wird” (“which provides … and is called”), thus the overall subclause is not elliptical after all. In this case, the absence of a relative pronoun in the fourth line would indicate that the reference is still to “das” (“that”) in the first line. I take the second reading to be the correct one, but whether the first or second reading is correct does not really affect my interpretation, although the second perhaps fits it better.

In line with the second reading, Kant is saying that the guarantor is called “fate” (“Schicksal”) insofar as the device of producing unity through strife is taken as necessitation or coercion through an unknown cause. Note, though, that the personification of nature as the great artist occurs prior to the identification of the guarantor as fate. Moreover, in a further step of reflection the guarantor is taken to be “providence” (“Vorsehung”), and this connects it to a wise cause that aims at the objective ultimate purpose of humanity.Footnote ¹⁸ It is this move in particular which has been met with surprise, to say the least. Providence, for Kant, is accounted for with regard to purposiveness (in terms of an analogy to the production of artefacts). At the same time, he considers the idea of providence being in agreement with this ultimate purpose, that is, presumably as instrumental for its fulfillment, to be “effusive” (“überschwenglich”) in theoretical terms, but feasible in practical contexts. As an example of such a practical context, Kant proposes “to use that mechanism of nature for it,” and “it” in all likelihood refers to the “concept of duty of perpetual peace.”

Kant obviously does not regard the workings of the mechanism of nature, nor that of providence,Footnote ¹⁹ as incompatible with freedom as a requirement of duty, and he emphasizes the character of perpetual peace as a concept of duty. Later in the text he suggests that perpetual peace is closely connected to the final objective end prescribed by reason (TPP 8: 365.21–3).

I shall postpone a discussion of the compatibility problem(s) with regard to human freedom that arise here, and turn instead to the perplexing plethora of, on the face of it, different ends that Kant talks about in the opening passage of the guarantee addendum.

These are: (a) the objective ultimate end of a higher wisdom, that is, in all likelihood, God; (b) “the” end immediately prescribed by reason as a duty; and (c) perpetual peace as a duty or as covered by a concept of duty. Kant moves with striking ease from what looks like theological considerations in (a) to considerations pertaining to moral duties in (b) and (c), which, to be sure, do not apply in the case of God and his perfect will.

Let us start by looking at the connection between (b) and (c): As far as the relationship of perpetual peace to the end immediately prescribed by reason is concerned, suffice it to say here that the phrase “the end” could in principle be just a placeholder for “any end (immediately prescribed by reason).” In this case, perpetual peace would just be one of these ends. While this reading is a theoretical possibility, it is not very likely since one would expect an indefinite article instead, that is, something like “an end immediately prescribed by reason.”

If “the end” in question is different from perpetual peace, what could it be? Since Kant is concerned here with ends to be brought about rather than preexisting ends, it is, most probably, an end which is at the same time a duty, one of the key topics of the Doctrine of Virtue; there are two main candidates for such an end, namely, self-perfection and the happiness of others (MM 6: 385sq.). The adjective “immediately” would suggest something related to the agent personally and not to a third person, hence self-perfection looks like the more plausible option. “Immediately” may even rule out the nonmoral dimension of self-perfection (see MM 6: 392), since experience is required to find out which talents one possesses and, therefore, are supposed to be cultivated. Hence “the end” should be moralization or the full development of moral capacities.

On the other hand, physical self-cultivation is the ultimate end of nature, albeit only an intermediary end of creation as such in the CJ (5: 429–434)Footnote ²⁰, and for this end a “cosmopolitan whole” which, we can safely add, sustains perpetual peace, is the proximate means, so to speak. Since physical self-cultivation is also an end and at the same time a duty, one could argue that it is precisely the one referred to in (b) above. Clearly, though, moral self-cultivation has priority in Kant, with physical self-cultivation, in turn, being a precondition for the success of moral self-cultivation in terms of the acquisition of a stable good will. Kant’s usage of the definite article in the passage from the Perpetual Peace essay under consideration (8: 361.7) suggests that he indeed has in mind one end which is at the same time a duty and, since he uses the term “moral” to characterize this end, I take this to be moral self-perfection.

The next question, of course, is moralization of whom? Kant is talking about the human species, or humankind, in connection with the end in question. This phrase leaves it open as to precisely who is the subject of this moralization, since it is only individual agents who can achieve it. Kant’s phrase is not only compatible with a universal and a particular reading, that is, the moralization of each and every human being or of just a limited number, but the possible grammatical function of “des menschlichen Geschlechts” (“of the human species”) as a genitivus subiectivus manages to establish a vital connection to the objective ultimate end of a higher wisdom. Taken this way, the phrase does not indicate an end humankind ought to have but states that the human species or humankind itself is God’s end. This gives us a first hint at the connection between (a) and (b): The objective ultimate end of God is – or at least is essentially concerned with – the moralization of all, or at least some, human agents, provided we can understand “human species” in an emphatic sense, involving the actualization of the moral capacities of all or at least some of its members. We shall see in a moment, when looking at the guarantee footnote, that such a reading is indeed plausible.

The idea of taking at least some divine ends as the fulfillment of human duties will be crucial for approaching the idea of a guarantee of perpetual peace. The hitch, of course, is that in a Kantian environment, human agents need to bring about their moral perfection essentially by themselves.

Since (b) and (c) are different in the reading suggested, what is the relation between these two? Again, the details of this question will be discussed below. One way of reading Kant here is that he is assuming something like a hierarchy of both divine ends and human duties, in which some divine ends which are at the same time human duties are subordinate to others. Consequently, what is in one sense an end can at the same time be a means to something else. In a similar vein, the successful fulfillment of one duty may be a condition for the fulfillment of another. As I will argue in section 4 below, this structure is pertinent for understanding Kant with regard to the duty to work towards perpetual peace. Seen this way, the successful compliance with the duty of (working towards) perpetual peace is indeed a precondition for the successful fulfillment of a different, very special moral duty in the Kantian system, namely, the duty addressed to mankind of establishing the ethical commonwealth (see Rel 6: 94).

A further difficult question is whether perpetual peace is meant to precede or to come along together with ethical cultivation, and it seems that, at least in Perpetual Peace, moralization occurs within the safety of perpetual peace (TPP 8: 366). This will turn out to be consistent with the distinction between an imperfect and a perfect variant of perpetual peace.

Paradoxically, Kant’s remark about God’s end evokes a notion of divine agency as being involved, if not dominant, here, and this leads to a further issue. What I have in mind is Kant’s phrase “to use that mechanism of nature for it.” The obvious question that arises with regard to this idea, just as in the case of moralization, is that concerning the subject of such “usage.” Does it refer to the intellectual enterprise carried out in this section as a whole insofar as we (along, of course, with mainly Kant himself), who are reflecting on the feasibility of perpetual peace, may “use” – in the sense of “draw on” – the notion of a mechanism of nature to come to terms with this problem? This reading may be called the “reflective usage reading.” Or does it refer to something more mundane like deliberation, in particular political deliberation, in that human agents, especially those in charge of political entities, are supposed to utilize the mechanism of nature in order to achieve the ends to which they are obligated by practical reason? This interpretation may be called the “technical usage reading.” I will try to show below that neither reading, nor their combination, is fully plausible, or at least that neither can capture all that Kant has in mind here.

2.3 The Guarantee Thesis

With this in mind, we can now turn to Kant’s guarantee thesis. At the end of the guarantee addendum Kant says:

I take the term “certainty” (“Sicherheit”) here not to indicate a psychological property of a judgment or claim, but that we are warranted in maintaining the proposition in question. In this manner, it may indeed be something like an epistemic property. In the case at issue, we are not warranted in a theoretical context to claim that perpetual peace will come about. But, what are we allowed to claim in this respect from a practical perspective?

At first view, this might seem to be a comparatively modest thesis, in that the contrast between a theoretical and practical perspective seems to coincide with claims concerning the future actuality and the mere (albeit real) possibility of perpetual peace respectively. In this vein, the guarantee of perpetual peace would both be a matter of the practical perspective and concern only its real possibility. One might think that this is only fitting because, for it to be a duty to work towards the establishment of perpetual peace, what we need is indeed the (real) possibility of perpetual peace, and this by virtue mainly of the principle “ought implies can.” To be sure, in this sense, (real) possibility is only a necessary condition for this duty to hold, but still, establishing this possibility would be a substantial point. Kant’s claim from the quotation above (TPP 8: 362.11) about the (presumably objective) “reality” of providence and its relation to and consonance with the end immediately prescribed by reason (even if this is not identical with perpetual peace) also, first and foremost, concerns its real possibility, not its actuality. Finally, the contrast Kant is making with “chimerical” may also be thought to indicate that perpetual peace is not impossible, which again would not necessarily amount to claiming its future actuality.

Still, there are indications that Kant understands the guarantee thesis in a more ambitious manner. Given the tenor of the overall text – for example, in the last sentence of the passage preceding the guarantee addendum (TPP 8: 360.7–9) – Kant does in fact have the prognosis of the future actuality of perpetual peace in mind, even though he concedes that such a claim falls short of genuine knowledge.

A distinction between a weak and a strong reading of the guarantee thesis has been suggested,Footnote ²¹ but both readings have been taken to be theoretical claims. According to the strong reading, “we can know that a state of affairs (perpetual peace) will take place” (Reference Caranti, Formosa, Goldman and PatroneCaranti 2012: 148). According to the weak reading, “we know (or […] there are grounds to be confident) that we are constantly approximating that desired goal” (Reference Caranti, Formosa, Goldman and PatroneCaranti 2012: 148). In both cases, it is recommended that we abstract from the question what, after all, is the guarantor power.

It seems to me that these two versions each have a practically justified correlate in which knowledge or theoretical cognition is replaced by something like practically warranted or “moral belief”, as Kant puts it in CPR A828/B856. Kant’s overall emphasis on the practical mode renders these correlates more attractive, since they allow us to do justice both to the accentuation of the practical mode and the claim of the future actuality of perpetual peace.Footnote ²²

Which of the two practically justified correlates does Kant have in mind? One important point to consider is the notorious passage MM 6: 350, which appears to suggest that perpetual peace is not realiter possible after all. Does this thesis rule out the practical correlate of the strong reading? In any event, the MM passage is concerned with the object of the guarantee, not the guarantor; it is not any guarantor’s fault that what is not realiter possible cannot be guaranteed in the sense of the state of affairs in question becoming actual at some point in time. Moreover, a denial of the real possibility of perpetual peace would of course rule out a fortiori even a reading of the guarantee thesis which takes it to secure precisely this real possibility. Conversely, there could plausibly only be a duty to “strive toward the constitutional perfection of one single state of nations” (Reference Byrd and HruschkaByrd and Hruschka 2010: 203).Footnote ²³

There is no indication at all that Kant denies the real possibility of perpetual peace in the essay Perpetual Peace; he rather seems to think that since there is the duty to bring it about, perpetual peace is realiter possible.Footnote ²⁴ For this reason, I am going to ignore the MM passage here and focus on his position in the essay. Moreover, I will try to show that Kant does have the resources to establish the practical correlate of the strong reading, and I take this to cover the practical version of the weak variant as well. Due to space limitations, I will say little about Kant’s idea of a mere asymptotic approach to perpetual peace (e.g., TPP 8: 386). I take this to be indicative of his concession that he is indeed in a defensive position with regard to the future actuality reading of the guarantee claim. The mathematical notion of a limit indicates the outermost tip of actuality, as we can perhaps put it.Footnote ²⁵

In this vein, and as far as terminology is concerned, the term “future actuality reading” comprises both the weak and the strong version and is neutral as to whether this is intended to be a theoretically or a practically justified claim. The term “modest reading” covers anything short of the future actuality claim.Footnote ²⁶

2.4 Varieties of Cooperation

At any rate, we can expect to receive some elucidation of at least some of the points raised in the first paragraph of the guarantee addendum in the footnote referring to it (TPP 8: 361.5fn–362.39fn), although it must be said that it is a rather densely argued piece of writing, which does not immediately reveal its secrets. As we shall see, the guarantee footnote does indeed clarify important metaphysical issues related to providence and concursus. However, at least on the face of it, it also seems to put even more pressure on the idea that working toward perpetual peace on the part of humans is a matter of their freedom. Let us proceed step by step. Kant argues as follows:

Kant’s claim that as a “sense entity” (“Sinnenwesen”) man, along with other entities, also belongs to nature alludes to his distinction between appearance and thing in itself, with sense entity corresponding, by and large, to appearance, with all the intricacies this distinction involves. One particularly important problem that arises here is due to the fact that Kant, throughout his writings, invokes two very different accounts of this distinction, namely, a so-called two-aspect (TA) and a so-called two-world (TW) model. It is not easy to pin down precisely what the difference is between these two models, particularly because a huge variety of different versions of each of them have been developed by Kant’s commentators over the years.Footnote ²⁷ The suggestion that the difference simply boils down to whether the model does or does not subscribe to the identity thesis according to which each appearance is numerically identical with a thing in itself cannot be correct. Plainly, since things in themselves do not have spatiotemporal properties they are not numerically identical to any appearance. The TA view, properly conceived, must maintain that appearances form something like composite wholes with things in themselves, although it remains to be seen how this idea can be spelt out in detail, for example, in terms of different types of properties. Along this line, the term “human being” (“Mensch”) may indicate such a composite whole, one in which a human being as a sense entity is but one element, feature or part constituted by its properties that are open to sensory intuition. Kant’s language in this sentence clearly suggests that there is something about the human being over and beyond nature and that may be exempted from the mechanism of nature.

His focus on “sense entity,” however, appears to support the view that freedom is lacking here, because in the world of the senses, causal laws reign, and this view generates a remarkable tension with the notion of duty that Kant repeatedly invokes with regard to perpetual peace.

2.5 Contexts

I should like to end this section with a very brief attempt at a contextual reading of the passages considered above indicating how they connect to other passages in Kant’s œuvre,Footnote ⁴⁰ partly reiterating what has been said above already.

Among Kant’s published texts the guarantee addendum provides the most comprehensive account of concepts concerning divine actions with regard to events in the world, and this account roughly corresponds to parts of the section “Operationes Dei” (i.e., §§926–981) in Baumgarten’s Metaphysica. Only the theology lectures (e.g., PhilTh-P 28: 1091–1117) and the theology parts of the metaphysics lectures – and here the Dohna-Wundlacken 4 notes of lectures held in 1792–3 are the closest in terms of chronology and with a surviving, albeit in this case comparatively brief, theology part (see 28: 690–702) – are more detailed.Footnote ⁴¹

A further important feature of the passages discussed above is that they involve a twofold cross-reference with key passages of the Critique of the Power of Judgement (1790) and of the Religion (1793), the two monographs of Kant preceding the essay Perpetual Peace. In addition to presupposing the moral argument, in particular, in its CJ version (5: 447–453), the pertinent sections there are marked by a similar, or perhaps better, reverse difficulty. While it is at least not immediately obvious why Kant mentions the concept of a cosmopolitan legal condition (see CJ 5: 432) in a context primarily concerned with natural teleology which, in turn, is preparatory to arguing for a practically grounded metaphysics, the difficulty in the guarantee addendum is the recourse to practically grounded metaphysics in a context primarily concerned with issues of philosophy of law and history. The second cross-reference is to passages in the Religion where Kant’s ideas about grace (e.g., Rel 6: 71–78, 190–192) and his normative claims about the ethical commonwealth (e.g., Rel 6: 94–95) correspond to the conception of concurrentism endorsed in the guarantor footnote.

Arguably, the cross-reference to the final section of the third Critique is part of an elaborate double strategy. The connoisseurs of the critical project will of course have been aware of the last words in a work with which the critical business is supposed to have come to an end (see CJ 5: 170), while the non-connoisseurs have been invited to consider Kant’s finely balanced position with regard to practically grounded metaphysics developed there.Footnote ⁴² In the guarantee addendum he raises expectations with regard to the guarantee of perpetual peace only to ‘disappoint’ them by admitting that theory on its own with its focus on nature as the guarantor power cannot live up to such expectations. At the same time, he provides the material on the basis of which the expectations can be met, but only in the downscaled mode of practical cognition and without explaining why this is the case.

It is, of course, striking that this strategy is deployed in a text predominantly concerned with matters of politics and history. While it is true that the issue of peace is first and foremost a political goal, Kant provides at least clues as to how this goal fits into a much bigger picture we can paint about the world from a practical perspective. When it comes to the issue of a guarantee for peace, which again is a political topos, and to a guarantee writ large in the case of perpetual peace, this bigger picture can provide the means to establish such a comprehensive guarantee, as we shall see in section 4. Within such a bigger picture, not available solely on theoretical grounds, perpetual peace is but an intermediary end to be brought about by us on the basis of something like political skills in the use of the mechanism of nature for this end by the “world author.” Before turning to this issue, however, we need to look at the problem of freedom, since Kant’s attempted solution elsewhere in his œuvre will turn out to be useful for understanding his position in this regard.

3.1 Facets of the Problem of Freedom

The notion of entrusting nature to divine planning – maintained, strange as it initially seems, by the critical Kant – certainly strengthens the idea that there may be something like a guarantee of perpetual peace. Anything involving duty, however, presupposes freedom, be it the core of the objective ultimate end or working towards perpetual peace.

However, the account of the world given so far, with regard to both appearances and things in themselves, is on the face of it rather difficult to square with the freedom of the finite rational agents.Footnote ⁴³ All the models of cooperation suggested by Kant, mere conservationism for nature and concurrentism for morality, are afflicted with this problem; yet, in the main text of the guarantee addendum Kant says:

The question we need to ask now plainly is: How can this freedom of the human agent (by virtue of which it can be a duty to work for perpetual peace) indeed remain “unscathed,” given the picture that emerges in the footnote of a predominantly divine agency that acts both with nature being subordinate to it and in a way that extends to a sphere beyond nature. As much as the guarantee addendum helps us penetrate more deeply into the practically grounded metaphysics sustaining Kant’s claims with regard to politics and history, it does not reveal all its intricate details.

In order to address the problem of human freedom, it is indeed crucial to distinguish different threats to this freedom. When speaking about ‘threats’ I simply take this as a short form for saying that certain truths or, more cautiously, claims (for example, in theoretical philosophy) render it difficult to see how the freedom thesis can be upheld with regard to human beings.

We need to properly differentiate threats that emerge from God and threats that emerge from elsewhere – for example, from the activity of causes in the world of nature, which from a theological perspective is the realm of created causes, even though these created causes may follow divinely enacted special natural laws.

On the part of God, we can distinguish the following three potential threats:

1. (1) His knowledge about our (future) acts might undercut the freedom of these acts. We can call this the (fore)knowledge facet of the problem of freedom.

2. (2) His causal activity of creation and conservation might undercut the freedom of human acts due to the radical ontological dependency of human agents this may be seen to involve. Accordingly, we can speak of an ontological dependency facet of the problem of freedom.

3. (3) His causal activity in the world in addition to creation and conservation (as the concurrentists have it) might undercut the freedom of our acts. This primarily concerns the issue of grace in the account of concurrentism sketched above. Hence, there is something like a divine contribution, involvement or, indeed, a concurrence facet of the problem of freedom. Plainly, if one really thinks that God does more than merely create and sustain the free causes in existence, then the question arises as to whether this doing more is compatible with the freedom of these causes and their actions.

On the part of causes other than God, the following threats to human freedom emerge:

1. (4) The causal activity of causes in the natural world different from God might be undercutting the freedom of the human agent. These activities could be both internal and external to the agent, and this threat can come in at least two variants, namely: (a) in the form of the natural causal determinism thesis discussed widely in the contemporary debate about the problem of freedom, with Reference van Inwagenvan Inwagen (1983: 56) providing perhaps the standard definition or account of this thesis to which I shall return below; (b) in the form of coercion through natural causes. Clearly, (a) and (b) do not amount to one and the same thing. While coercion is perhaps thought to be more obviously incompatible with freedom, the situation is very different with regard to the determinism thesis. Some compatibilists have argued that one might mistakenly take the determinism thesis to be incompatible with freedom because of an unwarranted identification of determinism and coercion. Strikingly, Kant does indeed speak of “coercion of nature” (TPP 8: 365.25–26, my translation) and of “compulsion” (TPP 8: 360.16, my translation) with regard to fate and we shall have to enquire how to understand this surprising move and how such a coercion, in particular, can possibly leave human freedom “unscathed.” The difference between determinism and coercion notwithstanding, we can speak of a natural causal facet of the freedom problem.

There are even further possible threats to human freedom, which are not necessarily linked to causality; for example, a threat arising from the nature of truth:

1. (5) One might wish to argue that the mere truth-aptness of propositions about future human acts is incompatible with their freedom. This is, of course, a different issue from the one arising in the context of perfect divine knowledge. One can call this the logical or truth-theoretical facet of the problem of human freedom. This is a topic widely discussed in the wake of Aristotle’s famous example of a future sea battle in De interpretatione I.9, but for Kant this problem is something which he does not even consider. Truth-aptness as such does not undermine freedom for him. What matters is the issue in virtue of what there are these truths.

In the account in our footnote, facets (1)–(4) are clearly pertinent and, as we shall also see, (5) can at least be relevant in elucidating Kant’s strategy.Footnote ⁴⁴

3.2 Kant’s Altered Law Compatibilism

The problem of human freedom is one of the most widely and intensely discussed problems in philosophy, and this also holds for Kant’s treatment of it. Of particular importance is the so-called “compatibility question,” that is, the very question as to whether human freedom can be upheld in the face of the threats it faces, and we have identified five of those threats in the previous section. In Kant’s œuvre, his endorsement of compatibility holds the two main parts of his philosophy together, as it were. In the CPrR (5: 4fn), he even calls transcendental freedom the ratio essendi of the categorical imperative.

As mentioned before, Kant, in the guarantee addendum, takes the compatibility question as having been settled, but it is worth investigating the main outline of why he thinks he has the means available for establishing this compatibility. This is not only important in its own right, but getting clear about this will hopefully help us answer the question as to why Kant thinks he can assume that there is a guarantee of perpetual peace in the first place.

In doing so, I cannot enter a critical discussion of this vast topic, but only sketch the main outline of his approach. Some of the key building blocks of his solution will turn out to be instrumental with regard to this goal. While the previous section consisted of a close reading of key passages of the guarantor section of the essay Perpetual Peace, which tried to shed some light on what indeed looks like foreign bodies in a work mainly devoted to philosophy of history and the legal half of moral philosophy, we now need to move away from this text.

In Kant, the most important facet of the problem of freedom with regard to compatibility is undoubtedly facet (4), and the key text in Kant’s works that addresses this issue is the solution to the third antinomy in the CPR (A532–A557/B560–B585).Footnote ⁴⁵ With regard to facet (4) Kant needs to have the resources to undercut what is now considered to be the standard argument against compatibility, the so-called “consequence argument,” developed by Peter van Inwagen. It must be said, however, that although Kant does not explicitly discuss this argument, it is widely agreed in the literature that it is the argument which needs to be defeated if compatibility is to be secured.

This argument is meant to show that determinism and freedom or, to be more precise, the freedom thesis and the determinism thesis, are incompatible, that is, they cannot both be true. That they are incompatible is not a matter of course, which is often overlooked in discussions. Sometimes, establishing the determinism thesis is taken as amounting to a refutation of the freedom thesis, but this simply presupposes that both theses are incompatible, which is supposed to be shown in the first place.

Similarly, it is of no use for establishing compatibility to attack determinism. Moreover, it is important to point out that Kant’s conception of freedom is not typically libertarian, while the consequence argument has originally been designed to attack such a symmetrical conception of freedom. Kant’s position is asymmetrically libertarian, as one can perhaps put it (see MM 6: 226f.). This is to say, Kant holds that for an immoral action to be free the possibility of acting otherwise must be given, while this is not the case with regard to morally good actions. Since Kant clearly needs the claim that immoral actions are free, the argument does apply after all.

Now strikingly, premise (i) of this argument can be used in a very different manner or for an entirely different purpose, since if we take “our acts” to involve establishing perpetual peace, this captures the idea of a guarantee by virtue of the mechanism of nature very well.

Let us stay with the issue of the compatibility question, though, since – as mentioned before – some of the ‘devices’ to unseat the force of the consequence argument for incompatibility will give us a clue as to why the guarantee thesis holds for Kant. For premise (ii) to be false, at any rate, it is sufficient that the laws of nature or the distant past are in some sense at least up to us. The answer we can give on behalf of Kant to the consequence argument against compatibility – in a nutshell – is that, to a certain extent at least and as surprising as this may initially sound, it is in fact up to us what the laws of nature are. This is the core idea of the so-called altered law compatibilism (ALC).Footnote ⁴⁶

In a similar vein, the so-called altered past compatibilism (APC) maintains, no less surprisingly at first view, that the distant past is, in a sense to be qualified carefully of course, up to us. I will focus on ALC, though, in order to save space, and the law issue will turn out to be pertinent with respect to other components of Kant’s overall position with regard to a guarantee of perpetual peace.

The key elements in Kant’s solution are the following (see CPR A532–A537/B560–B565): In order to safeguard freedom strong enough to sustain morality we need to be able to uphold transcendental freedom, the ability to bring about a state of affairs spontaneously – and this in the face of the determinism holding in the world or realm of appearances established through the means of theoretical philosophy (whatever these may be precisely). For Kant, this kind of freedom is only feasible when the bearer of this freedom is located in the realm of things in themselves (remember this distinction is mentioned by Kant in the guarantor footnote) and the effects of this freedom occur in the realm of appearances. This claim is of course not without its own problems, but my aim here is to sketch Kant’s solution rather than to defend it.

Since freedom, in some sense at least, is something like a causal power, and every efficient cause needs to have a character, there must be something like an intelligible character of the noumenal agent or agent as a thing in itself, just as the agent as a natural cause must have an empirical character. A character of a cause, in this sense of the term “character” at least, is for Kant a law of its causality (CPR A538f./B A566f.).

In the first Critique (CPR A556/B584), this intelligible character is something like a contingent feature of each of these agents; their respective intelligible characters could have been different. Moreover, for Kant, it is not caused by anything external to this agent, but is due to the will of the individual agent. In the second Critique (5: 98) and in the Religion (6: 27, 31f.) Kant expands upon this idea and maintains that these intelligible characters have been acquired by the noumenal agents themselves.

In addition to this, in case of human free agency there is a counterfactual dependency of the empirical character of the agent on its intelligible character. A different intelligible character would have resulted in a different empirical character (CPR A556/B584). Finally, the empirical character is a sign or effect of the intelligible character for Kant (CPR A546/B574). In short, for Kant, in case of free agents their empirical characters are derivative from their intelligible characters.

We are thus beginning to see how this strategy can aim at undermining premise (ii) in the consequence argument. In summary, at least some of the laws of nature are up to us insofar as our intelligible characters are up to us. Since the empirical character provides the special laws of nature required for a naturalist explanation of the effects of the free action in the realm of appearances (in turn indispensable for Kant’s methodological naturalism), the laws in question reflect the intelligible character; a different intelligible character could and indeed would bring about a difference in the special laws of nature, and since the intelligible character is due to the individual free agent, some of the special laws of nature can also be said to be due to this free agent.

According to this reading, the noumenal free agent makes a difference in the realm of appearances by influencing what the special laws of nature are, which in turn make up its form, as I said above.

Let us now look at the notion of an intelligible character more closely. What exactly is this intelligible character? How can we understand it? What is its status? In particular, how is acquisition of it supposed to work, how counterfactual dependency? Here, we can seek help from what looks like an unlikely source, but one which fits perfectly well with the dogmatic tone of the footnote.

As I said, passages in the guarantee addendum and, in particular, in the guarantee footnote sound as if they belong to the kind of dogmatic metaphysics overcome in and through Kant’s critical turn. They are best read as spelling out what, exactly, we commit ourselves to when accepting or assuming the existence and the pertinent concept of God on practical grounds. This includes how these commitments can be rendered coherent with the results of the transcendental approach to the sphere of space and time – for example, its objects being subjected to causal laws. Assuming the existence of God in accordance with the concept of him sustained by the moral argument requires the assumption of the real possibility of God, and it requires assuming the logical possibility that this real possibility coexists with the real possibility pertinent to the realm of appearances and the conditions of the possibility of experience. Put somewhat differently, we have to spell out how an entity with all the attributes ascribed to it from practical considerations can ‘coexist’ with the transcendental ‘machinery’ argued for mainly in the transcendental analytic.

Similarly, the claims about an intelligible character are best viewed as conceptual implications of the assumption of transcendental freedom. As indicated above, we might wish to call this the libertarian, or asymmetrically libertarian, element of Kant’s practically grounded metaphysics as opposed to its theist part. Both lie beyond the realms of genuine knowledge, since we do not have a corresponding intuition which would be required to complement the conceptual claims.

For the sake of its internal consistency, this libertarian part also needs to be compatible both with the other parts of the practically grounded metaphysics and with the transcendental account of the realm of appearances. It must be logically possible that both natural determinism and transcendental freedom and, along with it, the intelligible characters are both actual and hence both realiter possible, each in its own way.Footnote ⁴⁷ If we have reasons to assume the actuality of transcendental freedom, as we must by virtue of morality, we must assume the actuality and hence real possibility of an intelligible character, although we cannot know how real possibility can be accounted for in the realm of things in themselves.

Finally, the theist part and the libertarian part need to fit together, but investigating this concerns the other facets of the problem of human freedom which we will consider in more detail below. This theist part, as we shall see in a moment, is at least to some extent also used by Kant to illustrate the compatibility of human freedom with his transcendental account of the world in space and time.

3.3 Intelligible Characters and Counterfactuals of Freedom

The notion of the intelligible character is a contentious issue in Kant scholarship. One way of making sense of it is to draw on an idea developed in the early modern debates about human freedom,Footnote ⁴⁸ that is, in an environment where many of the key concepts discussed and transformed by Kant, such as “providence” and concursus, were developed and investigated. This is the idea of what nowadays is called a “counterfactual of freedom.”Footnote ⁴⁹ By virtue of the epistemological qualifications just reiterated, this is not, of course, to suggest that Kant regards or is committed to regarding this doctrine as a theoretical truth and the object of human knowledge. Rather, this idea is a conceptual commitment in the wake of our endorsement of transcendental freedom which hinges on the validity of the categorical imperative.

In addition to this, the idea in question had originally been devised within theories meant to reconcile the compatibility of divine knowledge and human freedom, that is, the foreknowledge facet (2) from our list in the introduction to this section. Within these debates, one particularly important question concerned the truth of propositions about how free agents would behave in certain circumstances, and the divine knowledge of these propositions in the so-called scientia media.Footnote ⁵⁰ As we shall see, however, the idea in question is sufficiently rich to be applicable to other facets of this problem as well; most importantly, to the issues pertinent in facet (4), the natural causal facet of the problem of freedom.

One plausible way of reading Kant’s conception of the intelligible character is indeed to take an intelligible character of a free agent to consist of all the true counterfactuals of freedom valid for this free agent. The structure of a counterfactual of freedom (“cf”) is as follows: If person P were in situation S, they would freely perform action A. We may call “P were in Situation S” the antecedent (“a”) and “P would freely perform A” the consequent (“c”). Rendering the structure of a cf in a more formal way, it would be something like a□→c. In some accounts of cfs in the literature, both in a and c, a specific point in time is indicated (“at t”),Footnote ⁵¹ and there are restrictions as to what is feasible as a proper account or specification of a situation. Crucially, this framework allows us to distinguish what the agent could do in the specified situation and what the agent would do. Moreover, this framework allows us to maintain that instead of what the agent would do, the agent could do something else, so that what the agent would do is up to the agent.

Two main arguments support the identification of the intelligible character of a noumenal agent with the counterfactuals of freedom true of this agent. First, the identification coheres well with the definition of “intelligible character” in terms of a law of causality, since it is precisely the function of a law to provide the information about how the agent would act in all possible circumstances. Second, a recently proposed principle which elucidates how there can be true counterfactuals of freedom can provide an account of the acquisition of the intelligible character. This principle, usually called GP+ or the “extended grounding principle,” says:

In the literature on Kant, there are basically two types of accounts as to how, for him, the intelligible character is acquired. According to the first conception, the acquisition comes about in a timeless one-off action reminiscent of the motive of a choice of a form of life in Plato’s Republic.Footnote ⁵³ According to the second conception, such an acquisition is to be construed in terms of the sum total of the agent’s actions, or in terms of a function of a number of more conventional individual free actions of an agent, such as telling a lie.Footnote ⁵⁴ It has been suggested recently that these actions are all the actual past, present and future conventional free actions of an agent. My reading can strengthen the second conception in several important respects and retain its main advantage of what we can call a little-by-little account of character acquisition in terms of conventional free actions. What I propose in line with the idea underlying GP+ is to construe this acquisition precisely in terms of all the actions an agent would freely carry out in all possible situations. Since these hypothetical actions are actions of each individual will and are not necessitated by anything external (nor internal) to the individual will, the character consisting of all the cfs may indeed be said to be acquired by the agent. In this manner, the agent herself in and through these hypothetical actions adds a set of truths about herself to the set of truths which hold about that agent but over which the agent has no control.

The hypothetical free actions are those by virtue of which the consequents of the cfs are true. This means that individual actions account for the generality of the law which makes up the intelligible character; this law cannot be used as an explanation of these actions and is therefore not a law of nature. Seen this way, the account given so far also covers facet (5) of the problem of freedom: it is not the case that the presence of any truthmaker threatens freedom. The presence of those truthmakers does not do so which are due to the human will. In the account suggested, it is therefore not the case that the truth of the consequents in the cfs preempts what the agent would do in the situation specified in the antecedent. Rather, the action in question is the truthmaker,Footnote ⁵⁵ and this, again, is consistent with the agent being able to act otherwise and the action being up the agent.

Of course, the intelligible character cannot be known by a human observer, but this does not speak against this conception, since truth and knowledge about it can be separate in Kant, at least as far as the realm of things in themselves is concerned. Still, somebody who could know how each individual agent would act in each possible situation has important knowledge about that agent. Arguably, anybody who claims to know the Gesinnung or fundamental attitude of an agent would need to know the intelligible character as understood in this manner.

Indeed, insofar as Kant speaks of God as the scrutinizer of the heart who does know the Gesinnung of each agent (e.g., Rel 6: 99), and insofar as Kant assumes that knowledge of Gesinnung presupposes knowledge of what an agent would do in (sometimes challenging) situations (see MM 6: 392–393) which do not need to become actual, Kant ascribes such knowledge to God.

In this manner and understood in this way, the notion of the intelligible character fits in well into Kant’s take on the multifaceted problem of human freedom and indicates that the original point of the early modern debate, namely, that we should take counterfactuals of freedom to be the object of a special form of divine knowledge, is still detectable in Kant.

We should therefore not be distracted by the fact that in the lectures on natural theology Kant dismisses scientia media as a useless distinction (PhilTh-P 28: 1055), since what he dismisses under this heading has almost nothing to do with the early modern conception of it. Kant’s talk of God as knowing the Gesinnung of an agent is indicative that, implicitly at least, Kant concedes something like middle knowledge as originally conceived. Nonetheless, attributing such a type of knowledge to God is again a doctrine pertaining to practically grounded metaphysics, not something we are licensed to claim as a theoretical truth.

With this settled we can move on. The counterfactual dependency or, more broadly, the derivative status of the empirical character, and hence of the special laws of nature with regard to the intelligible character, can be elucidated further in terms of Kant’s doctrine of the regulative use of reason. For example, he maintains in Rel 6: 142 that God needs to be regarded as the origin of laws of nature, and in CPR A694–A697/B722–B725 that within the regulative use of reason we need to regard the systematic unity of the world and of the laws describing it as originating in God’s creative intellect. Passages in the CJ, such as 5: 180, point in similar directions, and there Kant even focuses on “particular empirical laws.” To be sure, the mode in which these claims can be made is not that of knowledge.

These passages indicate that for Kant the special laws of nature are due to the divine intellect, but this does not tell us why the laws are as they are. With regard to this question we get some hints in the “Doctrine of Method” section of the first Critique; these are passages which explicitly support the idea of God as that in virtue of which nature and freedom coincide. Kant now focuses on the divine will, which is, of course, pertinent for the implementation of laws:

These passages suggest that we need to include a special predicate in the concept of a divine will in order to secure the agreement of nature and freedom. One way of illustrating how this agreement can be achieved is to assume that special natural laws are enacted which somehow reflect the intelligible characters. In order to be in a position to do this, the will in question must be eternal, that is, beyond time.

Kant offers a more detailed account when bringing together the libertarian and the theist lines of his practically grounded metaphysics in the lectures on natural theology, expanding upon the hints he gives in the critical works themselves. What he says there points exactly in the direction just mentioned. These lectures, of course, are not on the same footing as Kant’s published works.Footnote ⁵⁶ However, and as we shall see, what he is said to have laid out in these lectures complies exactly with what he is logically committed to by virtue of the interconnection of positions possible with regard to each facet of the problem of freedom.

In a sense the lectures are, at least in principle, appropriate to consult for our purposes since there we find a more comprehensive treatment of his practically grounded metaphysics; they are in this respect rather close to what he is doing in the guarantor footnote.

Strikingly, in his lectures on natural theology, Kant accounts for the derivative status of the special laws of nature in terms of his conception of providence. As indicated in section 2, in the Pölitz lectures, Kant is reported to have defined “providence” as follows:

Crucially, he is reported to have added an important detail:

This passage can plausibly be read as indicating that the counterfactual dependency of the special laws of nature on the respective intelligible characters is based on divine knowledge of these individuals prior to the creation and the subsequent implementation of the appropriate special laws of nature. Had the characters been different, the special laws of nature would have been different, because different laws of nature would have been implemented.Footnote ⁵⁷

Clearly, some of the events Kant talks about in this passage must be (aspects of) human actions and, as he emphasizes a little later in the text, it must be in a human being’s power whether to observe or disobey the laws of morality, even though the choice of disobedience would be counter to the divine plan with regard to the moral world.Footnote ⁵⁸

This rather more detailed and certainly less abstract account of ALC blends in nicely with a key result obtained in section 2, namely, the identification of nature in a formal sense and providence in the object sense when regarded from the perspective of the unity of theoretical and practical reason. What we have now is the addition of the idea that this formal aspect of nature reflects, or is at least in part due to, human freedom. In this manner, we can also make some sense of the idea expressed in one of the key sentences of the guarantor footnote that this form of nature has been “determined beforehand” by the world author, and we can see now that determination is at least in one important respect epistemic insofar as this form must be in accordance with the intelligible characters of the human agents. The determining is at the same time constitutive since according to this view the laws are implemented through the divine will.

But what are special natural laws which reflect the intelligible characters? Along the lines of the reading of the intelligible character suggested, one minimal condition could be as follows: The special laws of nature must be such that they sustain counterfactuals about the agents taken as appearances – “counterfactuals of nature,” as we could call them – with the same antecedents and consequentsFootnote ⁵⁹ as in the counterfactuals of freedom. The difference between a counterfactual of freedom and a corresponding counterfactual of nature would then be that, when taking the special laws of nature as fixed, it is not up to the agent – when regarded as an appearance – how to act in the situation described in the antecedent. In this vein, it is what has been called the “order of nature” itself, which turns out to be at least in part due to human freedom; within this order of nature the mechanism of nature can do its work.

3.4 Multifaceted Compatibility

As shown above, there are at least five different facets of the problem of freedom that are relevant for Kant and detectable in the guarantee addendum, each corresponding to a doctrine which threatens to undermine human freedom, namely: (1) the facet of divine foreknowledge; (2) the facet of creation or ontological dependency; (3) the concurrentist facet; (4) the facet of natural causal determinism; and (5) the truth theoretical facet.

While the natural causal facet (4) of the problem of freedom is clearly the most pressing and important one, the other four are situated more on the periphery, especially as far as scholarly discussion is concerned. Nonetheless, the solutions Kant proposes for each of these facets are in an important sense interconnected, since positions with regard to the foreknowledge facet (1) have implications for those with regard to the natural causal facet (4) and the truth theoretical facet (5), while positions taken with regard to the creation facet (2) have, in turn, implications for those with regard to the other three. If Kant were to explain divine knowledge about human free agency in terms of God’s bringing about truths relating to the intelligible characters, it is difficult to see how he could maintain that the intelligible characters are self-procured by the individual agents. Similarly, if Kant were to maintain that through creation God fixes the truth values of the cfs that make up the intelligible characters, how could these truth values still be regarded as being due to the agents themselves? Conversely, such a position with regard to creation would fit well with an explanation of divine knowledge of these truths by virtue of some kind of maker’s knowledge in respect of the intelligible characters, as we might wish to put it.

Indeed, with regard to facet (2), the pertinent passages in the second Critique (5: 100–102) and the Religion (6: 142–143) all suggest, or make sense on, the assumption that there are no options on the part of God with regard to the human free agents he can create, in the sense that it is beyond his control how they use their freedom, that is, which intelligible character they acquire. In the Religion, Kant goes even as far as to say that we need to represent the free agents as if they preexisted and thus as exempted from the creation thesis for the sake of their freedom. True, this claim seems to contrast with Kant’s mere conservationism, expressed in the example of the physician and his remedies in the guarantor footnote (TPP 8: 361.39–362.32fn) and discussed above in section 2. Recall that Kant clearly says that if one wishes to ascend to the Urgrund or first ground of all things, the physician and his remedies need to be regarded as created and God, in turn, regarded as the sufficient cause for the recovery of the patient in question. Strikingly, in the example, Kant completely abstracts from the question of free agency and treats the actions of the physician merely as natural events. In this vein, Kant can be read as maintaining that when taking the recovery of a patient as the effect of natural causes, we can – in the framework provided by his practically grounded metaphysics – alternatively regard it as the indirect effect of divine creative activity, although, and this must be stressed, this would not amount to a proper explanation for Kant.

This reading does not by itself commit us to saying that for Kant the same is true when regarding the recovery of the patient as the effect of a free action by the physician (regarded as a thing in itself). Plainly, when taking the physician as a free agent, we cannot fully ascribe the action to God. Moreover, the passage in the Religion insists that, for the sake of freedom, we even need to represent the free agent as preexisting and exempt from divine creative activity, since otherwise we would have to take the alleged free cause to be configured by the creator. Accordingly, Kant’s emphasis really seems to be on maintaining that the intelligible characters of agents are something pregiven even to God and that he has no choice about which free agents can be rendered actual. Accordingly, with regard to facet (1), God’s grasp of these intelligible characters should be taken as tracking truths rather than bringing them about.Footnote ⁶⁰

By virtue of this relation of the facets described so far, Kant can be read as trying to avoid positions which endanger the self-procured status of the intelligible character (which, in turn, is the key claim of his libertarian compatibilism).

Facet (3) might be approached by considering a similar idea at work here too, but this of course would require far more detailed enquires than are possible here. Suffice it to say that Kant’s surprising statement about the indispensability of the notion of concursus with regard to grace in the guarantee footnote is consistent with him distinguishing, implicitly at least, what has been called prevenient and justificatory grace.Footnote ⁶¹ While in the second piece of the Religion Kant is evidently and primarily concerned with justificatory grace and the problem of something like a divine “pardon.” The passage in the guarantee footnote, by contrast, can be read as having to do with prevenient grace. Moreover, what Kant says is consistent with the idea that justificatory grace presupposes the effect of prevenient grace (for reaching a state of mind – in this case, faith – indispensable for pardon) and that the coming about of this effect, in turn, presupposes human cooperation which is beyond God’s control.Footnote ⁶²

Facet (3) is important because it touches upon the ultimate end of the world author. As we have seen in section 2, this end is concerned with the moralization of human agents and the suggestion in the pertinent section of the guarantee footnote seems to be, rather surprisingly, that grace, and along with it concurrentism, is indispensable for this.

Provided that my brief sketch of Kant’s strategy for tackling the problems related to facet (3) is correct, a common feature of his position with regard to all the five facets of the problem of human freedom emerges. For Kant, there seems to be some sort of priority of human free agency, even in its hypothetical employment, with respect to which nature, truth and, in certain respects at least, even some features of God himself are derivative. This is perhaps particularly striking with regard to God’s knowledge of the intelligible characters of the free agents, and in the next section I shall provide further, more direct evidence for such a reading. Along the lines I am suggesting, this knowledge should be regarded as truth tracking and hence as limiting the options of what he can do. Understood in this manner, God cannot make it the case that – as we need to put it in the parlance of cfs – an agent would act differently from how they would in fact act in a certain situation. Similarly, according to my account of facet (3), God cannot even ‘force’ human agents into moral goodness through grace, since even in this regard God needs to rely on human cooperation.

To be sure, emphasizing the priority of freedom makes it more difficult to establish both the compatibility thesis, with regard to each and all the different facets of the problem of freedom, and the guarantee thesis as well, so I take it that this point can be granted for the purpose of my argument even though it merits a more comprehensive treatment.

While, when seen in the manner suggested, the options of divine agency are restricted by virtue of human freedom, the situation with regard to knowledge is nonetheless markedly different, and this is precisely because of the knowledge regarding the intelligible characters. This suggests that the way open to a God conceived of in terms of a practically grounded metaphysics for succeeding in obtaining the actions wanted from a free agent is for God to bring the agent into a situation in which God knows the agent would freely act in this way.

Arguably, this way of handling free agents is in the widest possible sense political – political in the realm of metaphysics even – but the problem is that, given Kant’s very stance on the priority of human freedom, it is not a matter of course that these free human agents would ever act in the way they should. Put differently, it is not obvious why the intelligible characters are such that they lead to special laws of nature which play their part in securing perpetual peace.

4.1 The Guarantee of the Objective Ultimate End

Let us now examine why for Kant the coming about of the objective ultimate end of creation is certain. It must be said, though, that Kant does not state this point explicitly, but it follows from a number of key assumptions he makes.Footnote ⁶³ In order to see why this is the case, we need to look at the extraordinary sentence from the main text of the guarantor addendum again.

What Kant is saying in the latter half of this passage is this: When it comes to the consonance of providence with the moral end immediately prescribed by reason we transcend the realm of theory, but we are entitled to claim this from a practical perspective. In section 2, it was argued that this end is the free acquisition of a good will by at least some of the human agents.

In the guarantor footnote, the form of nature – which, as argued above, from the standpoint of unified reason is identical to providence in the object sense – is explicitly connected to the “end of a world author” by Kant. I said above that I take this end to be the “objective ultimate end,” but as we shall see, the argument works just as well with ends subordinate to it. Let us look at the relevant passage again:

The question is: Where could the certainty with regard to achieving this end come from? According to Kant, and as explained above, the moral argument not only provides grounds for accepting the existence of God, but a determinate concept of God as well. In the intension of this concept, as set out in CPR A815/B843 for example, we find traditional predicates such as omnipotence and omniscience. An enquiry into the precise conception of these predicates would lead too far here, but given the results in section 3 concerning Kant’s altered law compatibilism the alternatives can be stated quite boldly.

We have seen that, for Kant, the intelligible characters of agents ground at least some of the special laws of nature. One way of arguing for the certainty of the achievement of the ultimate objective end would be to say that, due to his omnipotence, God can simply configure or arrange the intelligible characters of the human agents in such a way that they lead to special laws of nature which, together with the material conditions provided by nature, lead to a course of events culminating in the actualization of the ultimate objective end. This very broad sketch would of course be in need of many more details and a great number of qualifications (in particular, since a good will is not something belonging to the realm of appearances), but the overall direction of the argument is perfectly clear.

While this line of reasoning coheres with not altogether unproblematic claims made in the secondary literatureFootnote ⁶⁴ according to which for the critical Kant – with all the qualifications which are required for such a claim pertaining to a practically grounded metaphysics – God necessarily creates the best possible world, I take this thesis not to be compatible with Kant’s ideas about the priority and bedrock status of human freedom. To be sure, should it be possible to uphold the priority and bedrock status of human freedom within this approach, it would be much easier to establish certainty with regard to the coming about of the objective ultimate end.

The difficult route to establishing this certainty starts from the assumption that the priority and bedrock status of human freedom implies that the intelligible characters are pregiven even to God, and limit his options of what world to create (with the latter again taken as a doctrine of practically grounded metaphysics, of course).

There is a further passage from the lectures on natural theology which supports this assumption and at the same time provides the resources for resolving the difficulties that arise along with it. To reiterate, these lectures are not on the same footing as Kant’s published works. Nonetheless, the passage in question fits much better with the priority and bedrock status idea Kant is committed to by virtue of the multifaceted compatibility claim he makes. This position, as has been shown in section 3, commits him to the idea that the intelligible characters are self-acquired by the noumenal agents rather than assigned to them by somebody else. In the passage in question Kant says:

This passage is remarkable in a number of respects. First of all, there is a clear distinction between the possibility of an external highest good and the capacity to “set [it] up.” Obviously then, this capacity is not a matter of course. This suggests that – again, as an assumption justified in practically grounded metaphysics – God realized or grasped that the intelligible characters, self-acquired by the noumenal agents, are conducive to this end. It is precisely this emphasis on the epistemic perfection of the divine intellect which accords well with the idea of the truth-tracking function of it with regard to the intelligible characters.

In this vein, there is no further reason as to why the intelligible characters are conducive to the actualization of the highest good. Rather, this has to count as the perhaps ultimate contingency.Footnote ⁶⁵ Given that God must be regarded as having created the world as a rational agent and hence on the basis of knowledge of the intelligible characters, practically grounded metaphysics licenses the assumption that he knew what would happen if he contributed his part in actualizing the world and, even more specifically, that he knew that in this case the objective ultimate end would become actual. We are even told that having the capacity to set up the best possible world was the reason for embarking upon the creative enterprise in the first place. As long as we assume the existence of God as specified in the concept developed so far, and since knowledge implies truth, we can therefore conclude that, since God did contribute his part in actualizing this world, the objective ultimate end will become actual.

While, in this approach based on practically grounded metaphysics, there is no further reason as to why the intelligible characters should be conducive to the actualization of the highest good, the very existence of the world is indicative that this is in fact the case. It is knowledge which compensates for the lack of control over the intelligible characters on the part of the God of Kant’s practically grounded metaphysics. Hence, delegating the actualization of the highest good to human free agents does not undercut the certainty of it coming about; the point is rather that one must acknowledge that this certainty is not a matter of metaphysical necessity.

4.2 The Path toward the Objective Ultimate End

Once it has been established that the intelligible characters of the human agents are conducive to the overall point of bringing about a world in the first place, we can see how delegating the actualization of this goal works on the basis of knowing these characters. William Lane Craig has illustrated this with regard to counterfactuals of freedom, in terms of which – as I have argued in section 3 – Kant’s notion of the intelligible character can be accounted for.

To every reader of Kant’s essay on Perpetual Peace, Craig’s account sounds perfectly familiar, since what we have in Kant’s text is the idea of a similar guarantor device for the end in question. Seen retrospectively, the historical development can be interpreted as having occurred in such a way that human agents made the suitable decisions to initiate a process toward the objective ultimate end of creation.Footnote ⁶⁶ Of course, and to repeat, perpetual peace is not the objective ultimate end, and we will get back to this issue again below, but at any rate the contours of how Kant’s guarantor claim can be rendered intelligible are beginning to take shape.

We have seen above that, in Kant, from the perspective of unified reason, nature in the formal sense of the term can be identified with providence in the object sense of the term. Moreover, in Kant, it is nature which also takes the role of setting the required conditions for starting and upholding the historical process, as his employment of the theatrum mundi metaphor suggests.

In the guarantee addendum (TPP 8: 365–368) we not only find the idea of something like a first set of conditions, but of an iterated or ongoing development of sets of conditions which in this text are described in legal and political terms. This mainly concerns the emerging imperfect legal systems which are, partially at least, the result of human action. Similarly, the transfer to a republican system in the as yet imperfect individual states, occurring through self-interest (against the background of a still unfettered propensity toward evil at the level of mature beings), brings about a new set of conditions. The same idea is present in the claim of a prevention of a certain possible development in that by means of the emergence of different languages and religions the establishment of a universal monarchy will be undercut. A universal monarchy would be an institutional setting unfit for perpetual peace (because of its ultimate collapse into anarchy and hence the destruction of even an imperfect legal order). Again, similarly and partially overlapping with the development of the conditions reached so far in the individual states, the emerging spirit of trade leads to a significant shift with regard to actions regarding their external relations, namely, according to Kant, to a gradual cessation of war.Footnote ⁶⁷

Abstracting from the at times bewildering details we are confronted with, the general structure of Kant’s account is quite clearly detectable: There was a set of antecedent conditions provided by nature in the sense that it was the result of events involving no specifically human contribution. Against the background of these antecedent conditions and owing to the mechanism of nature, humans – insofar as they are part of nature – performed actions which led to renewed antecedent conditions in which again certain actions occurred, the results of which, in sum, can in turn count as “stepping-stone(s)”Footnote ⁶⁸ toward the objective ultimate end of creation.

In light of these considerations, key points raised in section 2 can finally be clarified, albeit again with regard to the objective ultimate end first. In this section, I indicated that neither the reflective usage reading nor the technical-practical reading of Kant’s doctrine of a usage of the mechanism of nature for something which is a moral duty to be brought about can fully capture what Kant is aiming at. It is now relatively straightforward to see, against the background of a practically grounded metaphysics consonant with the findings of the transcendental account of the realm of space and time, that the subject of this ‘usage’ must be none other than the world author. This does not, of course, rule out that political agents should aim at something similar, nor that the idea of such a usage can help us come to terms with the philosophical problem of perpetual peace, but what we can call the “providence reading” of this doctrine occupies the focal position, at least in the guarantee addendum.

In a similar vein, it is now possible to elucidate Kant’s – on the first view – perplexing claims about nature as the guarantor power. On the one hand, Kant maintains that from a theoretical standpoint the term “nature” is appropriate out of epistemic modesty, while also insisting that the theoretical standpoint cannot provide the means for underwriting the guarantee thesis in the sense that the end in question will become actual. Still, Kant is endorsing such a future actuality reading nonetheless. We can read Kant in the following manner here: The guarantee in this strong sense and provided by nature is only available once we combine the theoretical standpoint with the standpoint of a practically grounded metaphysics and its rich notion of the world author as a rational agent aiming at realizing his ultimate end by drawing on the mechanism of nature. Seen from this unified standpoint, this mechanism of nature both feeds in the conditions and provides actions on the part of the human agents regarded as appearances, and these actions ultimately lead to the realization of the end in question. Moreover, this mechanism of nature is at least partially determined by human freedom.

4.3 The Ethical Commonwealth and Perpetual Peace

So far, we have discussed the guarantee thesis with regard only to the objective ultimate end. The strategy is now to show that perpetual peace is a condition for this end and that it therefore inherits this certainty.Footnote ⁶⁹ It is at this point that we encounter a serious difficulty, as Kant’s distinction of things in themselves and appearances becomes relevant. After all, the intelligible characters plainly concern the intelligible world of things in themselves and noumena. Simplifying a complex issue significantly, the point which arises is as follows. It is simply not clear why the ultimate objective end needs to be reached by embodied creaturely agents, that is, by free agents which form compounds with appearances. Is the second postulate of pure practical reason not a device precisely meant to transfer even the real possibility of the highest good into a transcendent realm? While it is, of course, not immediately clear how one can meaningfully speak of a future development of a ‘disembodied’ agent qua thing in itself, given the infamous atemporality of this realm, Kant clearly seems to think that this is possible.

Let us assume, however, for the sake of argument, that the end of creation – and I shall keep focusing on its unconditional part, namely, moralization – will indeed certainly come about immanently. This means that the end of creation comes about in the form of the ethical commonwealth,Footnote ⁷⁰ “God’s kingdom on earth,” as Kant puts it in the Religion (6: 93).

The reason, as we can read in the opening passages of the third piece of the Religion (6: 93–95), is that without such an ethical commonwealth moral self-perfection is only possible in a limited or negative manner, without removing the danger of a relapse into prioritizing concerns for one’s happiness over those regarding morality. A stable good will, the positive variant of moral self-perfection or, as Kant expresses it, the “reign” of “the good principle” (Rel 6: 93) cannot be achieved by embodied free agents in isolation, but in an adequate social context. This social context is the ethical commonwealth.Footnote ⁷¹

From there we can enquire about the consequences and the presuppositions of this, as we can call it, world immanent moralization within the ethical commonwealth. In order to accomplish this, we need to distinguish an imperfect form, that is, something like its “negative surrogate,”Footnote ⁷² and a perfect form of perpetual peace. Put simply and to anticipate, both are necessary conditions of immanent moralization, with the perfect variant of perpetual peace being temporally subsequent and the imperfect version temporally prior to immanent moralization.Footnote ⁷³ In the essay Perpetual Peace there are indeed indications of both conceptions. In TPP 8: 366 Kant claims that moral improvement or formation (“Bildung”) is to be expected within a good legal constitution, albeit with reference to particular states – but as we know, for Kant, a state cannot have a good constitution in isolation. In TPP 8: 378 he maintains in a phrase coined in Biblical terms that perpetual peace is a by-product of the good will. I shall now elucidate this idea of focusing on the presuppositions and consequences of immanent moralization in a bit more detail, starting with a short sketch of what, in Kant’s mind, the ethical commonwealth is supposed to look like.

As indicated above, the makeup of the institutional framework of perpetual peace is controversial, since it is unclear whether Kant requires a world republic or a maximally expanded, more or less loose federation for this end. What these two variants have in common is that they are not a first order world state, as a universal monarchy would be. A first order state has human beings as its members. For Kant, the ethical community, while not being a state-like entity in the sense that its laws are noncoercive, does have such a first-order structure. In addition to being a member of the state which is a constitutive member of the legal structure underlying perpetual peace, each human being is, in principle, an immediate member of the ethical commonwealth. Moreover, the ethical community is a cosmopolitan entity, a fusion of particular religions undergoing the process of enlightenment with some regional peculiarities surviving, and as such the truly universal church. The ethical community is thus the flip side of the legal structure sustaining perpetual peace, with this legal structure undergoing significant transformation through the establishment of the ethical community. I cannot discuss the question as to why the ethical community is essentially religious in nature here,Footnote ⁷⁴ but Kant seems to suggest that this is the case.

In any event, at this point we can draw on a probably uncontroversial principle, namely, the idea that certainty, understood in the way described above, is closed under entailment, that is, given that p entails q and that p is certain, then, in this case, q is also certain. Clearly, then, the certainty in question gets transferred to both the perfect and the imperfect version of perpetual peace. In other words, provided that we are entitled from a certain perspective – for example, religion or the practical standpoint in general – to claim the future actuality of the objective ultimate end of reason, then the (future) actuality of the necessary conditions of it must also hold.

In this case, we could conclude the investigation, were it not for the objection raised above, namely, that there is the logical possibility of what we could call an Augustinian, transcendent version of a certain future attainment of the end of creation. Along this vein, the spatiotemporal world and the persons acting in it would always be mired in the propensity toward evil and its social ramifications. Moreover, in such a scenario we could no longer claim that perpetual peace, in its imperfect variant, is a precondition of moralization, nor that perpetual peace in its perfect variant is a consequence of a good will situated in a transcendent realm.

Before addressing this objection let us look into the opposite idea of the immanent version of moralization and its implications in a little more detail. Indeed, throughout the pertinent third piece of the Religion (6: 93–147) in particular, Kant seems to make rather strong claims, namely, that moralization is something that happens at a certain time in history and is indeed only possible for the agents living at this time in history, because certain conditions need to be in place without which this moralization cannot occur. It is not obvious, though, whether these passages should also be read as a prognosis or merely as a claim about the duty to establish the ethical commonwealth.

The question is then of course: What happens to those unfortunate enough to be born at the wrong time? The second postulate of pure practical reason is perhaps pertinent here insofar as it enables a transcendent moralization as a way out for those who are dupés of world history, to modify Kant’s provocative phrase in Refl 7059, 19: 238 where he speaks of a “dupé of virtue,” however difficult it may be to conceptualize this ‘process.’ Whether this involves some sort of transcendent community in which such a moralization can occur (corresponding to the earthly ethical community) is something I cannot discuss here. I shall rather focus on moralization as something to occur in human history.

Suffice it to say that the difficulties arising from the apparent restriction of those eligible for a life in the ethical community can possibly be avoided if we assume that Kant intends to keep the two variants of moralization side by side and, to put it rather simply, an immanent and a transcendent version of the highest good along with it. As we shall see, however, for my argument nothing hinges on whether there is both an immanent and a transcendent unconditional aspect of the highest good, let alone whether there is an immanent and a transcendent version of its conditional aspect, although I do think this is in fact Kant’s position.

Now, this much is clear: Provided that we can establish that moralization will certainly be reached immanently, presumably side by side with its transcendent variant, we can regress on conditions. Moralization of agents requires the ethical commonwealth and this, in turn, the establishment of an institutional legal setting that sustains perpetual peace, while this institutional setting will itself be transformed in and through an ethical commonwealth.

Let us now address the objection of the exclusive transcendent actualization of the unconditional aspect of the highest good. How can we do this? One way is to try to establish that it is indeed constitutive for the end of creation to be realized in an immanent manner. We could argue (i) that there is the duty of establishing or uniting to form the ethical commonwealth, as Kant repeatedly points out in Rel 6: 94–95. Hence, if there is moralization with regard to human beings at all, and there must be moralization as it is the core of the objective ultimate end of creation, such a key duty cannot remain unfulfilled without compromising the overall end. Moreover, we could try to argue in a more metaphysical manner. We could maintain (ii) that Kant must assume that freedom in its perfect form and nature will be united since this ultimate metaphysical challenge cannot fail to be met when, and if, all parties concerned cooperate accordingly. Finally, we could resort to considerations of symmetry: (iii) the inclination toward evil arises in a social context, therefore it will be overcome in a social context.

I think that these arguments are successful in the end, in particular (i), but instead of examining this in more detail I shall rather explore a different line of thought altogether, which is by no means incompatible with the previous line. Strikingly, in a sense we might not need any argument for the actuality of immanent moralization to succeed and, in this case, we can in fact leave it open whether they do so. The reason is that the regress on conditions establishing the certainty of perpetual peace may also work on the assumption of the mere, albeit real possibility of an immanent actualization of the end of creation in the form of the establishment of an ethical commonwealth. After all, Kant clearly says in Rel 6: 94 that without an underlying legal entity the ethical community cannot be brought about. In addition to this, we can conclude that since the ethical commonwealth is supposed to be truly global in its extension, so must be this very legal entity at its foundation. Hence, this entity must be the one sustaining perpetual peace. Such an emphasis on real possibility would fit perfectly well with the idea that immanent moralization in a social context is an object of hope.Footnote ⁷⁵

This is Reference RossiPhilip Rossi’s (2019) point in his Element in this series, although he develops it in a context that is different from the certainty issue with regard to perpetual peace. Rossi reads Kant’s critical project in what he calls “anthropological” terms, and hence rejects a narrowly conceived epistemological account. For Rossi, humans are called upon to submit their multifaceted activities in the world to the reigns of reason. This includes the domains of politics and religion, and for Rossi it is important to regard the political and the religious as integral for the highest good possible in the world. Moreover, in Rossi’s opinion, the political project of peacemaking needs to be understood as embedded in the larger scheme of attempts to make the highest good actual. As I understand Rossi, a distinction of a perfect and an imperfect version of perpetual peace is endorsed, at least implicitly. Moreover, for Rossi, articulating this vision both in the philosophy of politics and in religion is essential for providing hope and guidance for these very efforts to succeed.

For Kant, at any rate, the actuality of the legal framework sustaining perpetual peace is indeed a necessary condition of the possibility of the ethical commonwealth, as the passages from the Religion (6: 94) indicate. Provided we can claim that it is certain that the ethical commonwealth is (realiter) possible in this world, we can draw on our inference pattern and conclude that the actual coming about of perpetual peace (in its imperfect form) as its precondition is certain as well. Clearly, it is fair to maintain the certainty of the real possibility of the ethical commonwealth in this world from a practical point of view since, as we know, for Kant it is a duty of humanity toward itself to establish or unite to form this commonwealth.Footnote ⁷⁶ Moreover, provided that by virtue of it being a duty to establish the ethical commonwealth it is also certain that it is a duty to establish the ethical commonwealth, we can draw on the closedness of certainty under entailment. In this vein, the real possibility of the ethical community must also be certain, in which case we can indeed draw on this inference pattern again and conclude that the (future) actuality of perpetual peace is certain. This coheres well with the idea that if there really is a duty of humanity toward itself to unite to form an ethical commonwealth (Rel 6: 95), then, plainly, at least some human agents must be in a position to do so.

Strikingly, this move reconfigures the argument developed so far in a significant manner. The idea had originally been to treat perpetual peace in its imperfect variant as a condition for something which is both the core of the final objective end of creation and a fulfilled duty on the part of human agents. Now, however, the focus is on the status of a duty, that is, something normative, namely, the duty to establish the ethical commonwealth regardless of its ultimate fulfillment and regardless of it being achieved as a divine end. In this vein, we have a shift from a practically grounded metaphysical to a moral argument.

Moreover, if there really is a duty to bring about the ethical community in the sense indicated, we can conclude that all the pertinent facets of the problem of freedom can be dealt with since freedom is itself a condition of duty. In particular, we can also conclude that the natural causal facet of the problem of freedom can not only be handled but that the special laws of nature are such that the coming about of perpetual peace is ensured. The question is then about our key sentence in the guarantee footnote (TPP 8: 361.5–8fn) which connects the form of the world to the end of the creator. The answer is that the framework of Kant’s practically grounded metaphysics provides some form of explication as to how the congruence of this form of the world of appearances and the duty to bring about the ethical community comes to pass.

We have thus, in fact, identified two possible strategies for arguing for the guarantee thesis in its future actuality reading, with the first drawing on the future actuality, and the second on the real possibility of the immanent form of the unconditional element of the highest good.