There is no contingency. All truths are necessarily true. Truth, possibility, and necessity collapse. However you put it, the thesis of A Case for Necessitarianism (Karofsky, Reference Karofsky2021) is radical. And with far-reaching implications given that modality permeates many (all?) philosophical subdisciplines. Threats to free will and moral responsibility are invigorated since prominent versions of compatibilism still require some alternative possibilities (e.g., Lewis, Reference Lewis1981; Sartorio, Reference Sartorio2016); counterfactual reasoning is rendered vacuous; and the meta-philosophical landscape is seismically altered if we are not constrained by the norm of explaining necessity (see Van Cleve, Reference Van Cleve2018, for examples) and if possibilities cannot feature as premises in arguments (see van Inwagen, Reference van Inwagen1998, for examples).

After summarising the history of necessitarianism, Karofsky (chapter 1) critiques the justification for (belief in) contingency. We can only experience what's actual: ‘it is impossible to experience what does not happen’ (p. 22). So, neither experience of change over time nor experience of variation between individuals justifies belief in contingency; I experience my cat increasing in mass over time but that's not to say that the cat at a given time could have had a different mass at that very time; I experience different cats with orange fur but that's not to say that my black cat could have been orange (p. 26). However, the literature on perceiving modality may complicate things here (e.g., Gibson, Reference Gibson1986; Nanay, Reference Nanay2011a; Reference Nanay2011b). And probabilities do not justify belief in contingency, according to Karofsky, given the availability of epistemic/subjective interpretations of probability (Karofsky also rejects intuition, majority opinion, and the prevalence of contingency talk as justifying belief in contingency).

In chapter 2, Karofsky criticises three theories of contingency: combinatorialism (e.g., Armstrong, Reference Armstrong1989), dispositionalism (e.g., Vetter, Reference Vetter2015), and modal realism (Lewis, Reference Lewis1986). Karofsky's concern with each turns on the idea (support for which she derives from Shalkowski, Reference Shalkowski1994) that contingency cannot be brute (pp. 50–52). Armstrong explains contingency in terms of recombination of the basic building blocks of reality. But the ‘building blocks’ are at the fundamental level so there is nothing more basic in terms of which to explain their contingency, which Karofsky thinks undermines combinatorialism. Dispositionalism (e.g., Vetter, Reference Vetter2015) accounts for contingency in terms of the manifestation conditions of dispositional properties. But since the stimulus for a disposition is (arguably) the manifestation of some other disposition, the stimulus of which is the manifestation of some further disposition, and so on, we either have an ‘infinite series of contingencies’ or an ‘ultimate basis for the contingency of all realized manifestations’ (p. 65) neither of which Karofsky thinks provides an adequate explanation of contingency. And modal realism fails, according to Karofsky, because ‘the constituents of Lewis's basis for modality [concrete possible worlds] are all necessary, and […] contingency cannot be rooted in necessity’ (p. 81) (though see, e.g., Cowling, Reference Cowling2011; Skow, Reference Skow2019 for a response). In fact, the idea that contingency cannot be rooted in necessity, which Karofsky calls ‘the principle of necessity’ (pp. 81–82), is relevant to the critiques of combinatorialism and dispositionalism too. Karofsky's general conclusion is that there can be no adequate theory of contingency, hence necessitarianism is true. She infers this from the claims that: everything is either necessary or contingent; contingency cannot be fundamental/brute; contingency cannot be ultimately rooted in fundamental necessity (pp. 82–83).

Chapter 3 presents the above argument in more detail and provides further reasons in favour of necessitarianism. Karofsky argues, ostensibly in opposition to essentialists (e.g., Fine, Reference Fine1994), that an ‘unbiased philosopher’ should not rule out any properties of an individual as uninteresting or insignificant (p. 97), which is consonant with the implication of her view that all properties of an individual are necessary to it. She argues that contingency is an ‘uncontainable contagion’ such that if anything is contingent then everything is contingent; it's not the case that everything is contingent, therefore nothing is contingent and necessitarianism is true (pp. 100–1). And she argues that Ockham's Razor cuts in favour of necessitarianism since its negation (‘contingentarianism’) requires more entities (e.g., mere possibilia) and more theoretical distinctions (e.g., between actuality and reality) (p. 103).

Chapter 4 responds to some objections. Counterfactuals are about merely possible situations and hence problematic for necessitarianism. Karofsky responds that counterfactuals are literally meaningless, since what they purport to be about does not exist, and she offers a reinterpretation of counterfactuals, though one on which they then cease to be counterfactuals. For example:

is, according to Karofsky, ultimately to be interpreted as the following true generalization:

Karofsky argues that certain knee-jerk responses to this strategy beg the question by just reaffirming contingentarianism (p. 114) and goes on to argue that the necessitarian can still make sense of the relationship between, e.g., counterfactuals and laws of nature (pp. 117–18) and of the relevance of counterfactual thought to guiding action (pp. 122– 24). Why write a book trying to change the beliefs of philosophers when beliefs are, like everything else, necessary? The desire to affect individuals’ future beliefs is, Karofsky maintains, consistent with there existing only one possible future (pp. 152–53), as is the pleasure and value in writing a book (p. 153). Moral responsibility is a matter of ‘looking out for the well-being of myself and others’ (p. 154), regret and pride are natural evolutionary responses that affect human behaviour, all of which is taken to be consistent with necessitarianism (pp. 155–57). In response to the worry that necessitarianism renders us little more than cogs in a machine, Karofsky gestures at the idea that we can nonetheless flourish by experiencing happiness and delighting in the happiness of others and reminds us that living with necessitarianism is possible as evidenced by Parmenides, the Stoics, Augustine, Spinoza, and Karofsky herself (p. 158).

I fear that many will remain unconvinced by the replies to objections: is it acceptable to render all counterfactuals meaningless? Or to address deep concerns about living with necessitarianism by gesturing at flourishing and noting the existence of prominent historical necessitarians? And what about the metaphilosophical implications of necessitarianism? A great many philosophical arguments and thought experiments are premised on possibilities. What becomes of these given necessitarianism? But let me now try to develop some other concerns in slightly more detail and use this to signal how the previous worries may be addressed in future work.

Since the ‘main argument’ (p. 91) for necessitarianism includes the premise that everything is either necessary or contingent (premise 1), I think the book could have discussed recent literature on amodalism (Cowling, Reference Cowling2011; Skow, Reference Skow2019; Reference Skow2022), which denies this very idea and instead maintains that some truths are neither necessary nor contingent (though I note that section 4.3, pp. 134–37, is relevant here). It might be maintained that the ultimate ground of contingency is amodal, in which case even if we grant Karofsky that contingency cannot be explained by further contingency and that contingency cannot be explained by necessity (which may be disputed, see, e.g., Kimpton-Nye, Reference Kimpton-Nye2021), it doesn't follow that there is no contingency since contingency could be explained by something amodal.

Furthermore, I have sympathy for Karofsky's interesting claim that contingency is in a sense ontologically suspect, which is touched on at various points in the book (see also Divers, Reference Divers2004, for an important contribution on this issue). However, I think it would be fruitful to consider whether an anti-realist account of contingency (e.g., Blackburn, Reference Blackburn and Blackburn1986; Thomasson, Reference Thomasson2020) might be of any help here. If anti-realism were applied just to contingency, would it follow that everything is nonetheless still really necessary and Karofsky's main thesis remains intact? I think this is a plausible interpretation of the resulting picture. But to properly motivate this view would again require a principled rejection of amodalism. This is because the most obvious/consistent option is to apply modal anti-realism to contingency and necessity. But then if pushed to answer the question ‘could the world really have been different or it is all really necessary?’, the thoroughgoing modal anti-realist must maintain that really the world is amodal (see, e.g., Cowling, Reference Cowling2011, p. 492).

The resources of modal anti-realism, which ‘provid[e] an intelligible explanation, in terms of the various facets of human life’ (Dasgupta, Reference Dasgupta2018) when applied to contingency, may help address the problem of accounting for counterfactuals and other problems associated ‘living’ with necessitarianism. And modal anti-realism may shed light on the metaphilosophical upshots of necessitarianism by implying, for example, that possibility arguments tell us about our own conceptual scheme and not about objective reality. The insights provided should be expected to vary depending on the brand of anti-realism, yielding plenty of scope for interesting research and fruitful lines of response to the problems for necessitarianism.

In sum, we should be encouraged by Karofsky to think in very general terms about the commitments of our modal beliefs and to question the default bias in favour of belief in contingency over necessity and use this as a springboard for a new wave of inquiry in the philosophy of modality.