1.1. State of the question

The expression “tacit knowing” itself is used quite loosely at times. Hoogenboom, for example, speaks of “synonyms for practical knowledge such as embodied, tacit or implicit knowledge” (Hoogenboom Reference Hoogenboom, Gehm, Husemann and von Wilcke2007: 83). Brandstetter stresses that dance leaves us “speechless” (Brandstetter Reference Brandstetter, Gehm, Husemann and von Wilcke2007: 43) (although she does not use the term “tacit”) and characterizes this kind of knowing also as “situational knowledge” (Brandstetter Reference Brandstetter, Gehm, Husemann and von Wilcke2007: 46). She locates the concept somewhere in between knowledge and non-knowledge, describing it as “knowledge that touches on the boundaries of knowledge and zones of non-knowledge” (Brandstetter Reference Brandstetter, Gehm, Husemann and von Wilcke2007: 43; see also Brandstetter Reference Brandstetter, Gehm, Husemann and von Wilcke2007: 43, 45–7).

Neuweg defines tacit knowing systematically: “The concept of tacit (or implicit) knowledge denotes that knowledge which manifests itself in behaviour in a wider sense, that is, in the processes of perception, judgement, anticipation, thought, decision-making or action, and which is not, not completely or not adequately explicable (verbalisable, objectifiable, formalisable, technicisable) by the subject nor, under some circumstances, by the analytical observer” (Neuweg Reference Neuweg, Rauner and Maclean2008: 725).Footnote ⁴ This definition already contains a “weak and a strong concept of tacit knowing”Footnote ⁵ (Neuweg Reference Neuweg2015 [2000]: 154). According to the weak concept, tacit knowing cannot be made explicit by the knowing subject. From a third person perspective, however, it is possible to convert it into a propositional form (Neuweg Reference Neuweg2015 [2000]: 154). An example of the weak concept would be the case of a physicist who analyses the action of cycling and determines the corresponding physical rules the cyclist follows (without being aware of them). The weak concept of tacit knowing is completely compatible with an intellectualist position (that every knowing-how can ultimately be transformed into knowing-that). According to the strong concept, tacit knowing per se cannot be made explicit (Neuweg calls this non-formalizability), i.e. we are talking about a kind of knowing which can under no circumstances whatsoever be translated into a propositional form (Neuweg Reference Neuweg2015 [2000]: 154). Being a radical anti-intellectualistFootnote ⁶, Polanyi endorses the strong concept of tacit knowing (Polanyi Reference Polanyi1966: 20f.; 1962: 53–5; Neuweg Reference Neuweg2015 [2000]: 161).

Apart from the weak-strong distinction, Neuweg also distinguishes a narrow and a broad sense of tacit knowing. The narrow sense is captured by the definition outlined above and describes a “gap between knowing-how and the possibilities of explaining the corresponding knowledge base” (Neuweg Reference Neuweg, Cramer, König, Rothland and Blömeke2020a: 764).Footnote ⁷ The broad sense, again, takes tacit knowing as a disposition and knowing-how in Ryle's sense (Neuweg Reference Neuweg, Cramer, König, Rothland and Blömeke2020a: 764).

Since I aim to discuss tacit knowing as a whole and not only specific subgroups of it, I will consider both the broad and the narrow sense, and, within the latter, both the weak and the strong concept. In section 2, I will show that neither the broad nor the narrow sense (not even taken together) are exhaustive definitions of the concept of tacit knowing. Both are too exclusive: the broad sense, being only concerned with knowing-how, excludes all cases of tacit knowing-that, whereas the narrow sense excludes some cases of both tacit knowing-how and knowing-that (namely those which are, in the end, explicable). In order to distinguish the all-encompassing sense of tacit knowing from Neuweg's broad sense, in the following I will speak of the wide sense of tacit knowing.

In this wide sense, the concept of tacit knowing comprises, among other forms of knowing, all cases of knowing-how and competences or abilities in general. At first sight this could clash with Neuweg's claim who, on the one hand, takes “Können [competence, ability, knowing-how]” as “something categorically different … from knowledge” (Neuweg Reference Neuweg, Hermkes, Neuweg and Bonowski2020b: 14). Still, on the other hand, he describes this ability as “knowing”. The apparent contradiction is dissolved if we consider that “knowing” needs to be strictly distinguished from “knowledge”. “Knowledge”, according to Neuweg, is “the freezing of practice” (Neuweg Reference Neuweg, Hermkes, Neuweg and Bonowski2020b: 20), whereas abilities or competences are dynamic and can be equated with “knowing” since this form of knowing manifests itself only in its application (Neuweg Reference Neuweg, Hermkes, Neuweg and Bonowski2020b: 14, 20): “Tacit knowing (or implicit knowledge) is practical by nature” (Neuweg and Fothe Reference Neuweg and Fothe2011: 340).Footnote ⁸

In the following, I will speak of “tacit knowing” rather than “tacit knowledge”. In the cases when tacit knowing expresses some kind of practical knowing-how it seems clear that we should stick to the progressive form since “knowledge” would be a concept too static to adequately include this kind of ability or competence (see above).Footnote ⁹ If we say that someone is able to do something, this already implies that the person has the corresponding knowing-how,Footnote ¹⁰ which, under normal circumstances, is identical with the ability. Those cases of tacit knowing that coincide with practical knowing-how could maybe be described more adequately as manifestations of abilities, competences, or even body intelligence.Footnote ¹¹ The capacity of adaptation, the flexibility, and situatedness characterizing tacit knowing seem to be typical for intelligence, whereas knowledge gives the impression of being rather static.Footnote ¹² Also Neuweg emphasizes being “interested in knowledge in use rather than in knowledge as a state” (Neuweg Reference Neuweg2002b: 41). For these reasons, I am using the term “tacit knowing” interchangeably with competence or ability as long as we are talking about tacit knowing-how.Footnote ¹³ Neuweg also speaks of tacit knowing inhering in abilities/competences (that would be the reason for calling it “tacit”), which suggests two different concepts (Neuweg Reference Neuweg2015: 7). Nevertheless, I consider such a separation as rather problematic, since ultimately both terms aim to capture the same phenomenon. Tacit knowing or abilities/competences inhere in actions, which are evidence to external observers that the subject is able to do something/knows tacitly how to do something.

In this context, the terms “competence” and “ability” are used in a very broad sense. After the foregoing explanations, we could intuitively object that in certain cases, competence, at least as long as the subject cannot adequately explain it or make it explicit (and that is mostly the case – unless we are talking about scientists analysing the rules they follow when they are cycling, for example), might have the same meaning as but still does not exhaust tacit knowing-how. For we can easily identify cases of tacit knowing-how which are prima facie not competences or abilities. Examples would be knowing what a melody sounds like or knowing what it is like to be a human being.Footnote ¹⁴ We cannot explain these cases of knowing in a propositional form, at least not sufficiently. Clearly, these cases do not represent expert knowledge or competence. However, it is worth looking again at Neuweg's definition of his tacit knowing view. It includes not only cases of expertise but also in a very general way “processes (e.g. perception, judgment, action, thought, discernment, contrivance) and the underlying human dispositions” (Neuweg Reference Neuweg2002b: 41). Consequently, these basic abilities or competences can also be subsumed under the heading of knowing-how. To sum up, the concept of tacit knowing-how includes cases of dynamic knowing which can express themselves both in masterful expertise and in forms of knowing at a more basic level.Footnote ¹⁵

1.2. Conditions for the attribution of knowledge

The foregoing explanations show that the concept of knowing includes quite different phenomena. In the following, I am going to discuss possible conditions for attributing full knowledge to a subject. In general, we need to ask if there even are such uniform and necessary conditions for the attribution of knowledge, or if we are in fact dealing with particular phenomena so differentFootnote ¹⁶ that it would be more sensible to speak only of family resemblances.

Many definitions of knowledge are limited to propositional knowledge (knowledge as justified true belief, Theaetetus 201c8-d2;Footnote ¹⁷ knowledge as justified true belief due to epistemic methodical security, Brendel Reference Brendel2013), thereby seemingly excluding a major part of tacit knowing (i.e. tacit knowing-how). Along these lines, scholars often argue for the reducibility of all forms of knowledge to propositional knowledge (so it does not matter if the definition of knowledge is restricted to propositional knowledge – since all the other seemingly excluded forms of knowing can finally be translated into propositional knowledge).Footnote ¹⁸

Insofar as this position includes forms of tacit knowing which indeed can be reduced,Footnote ¹⁹ this reduction, assuming that we deal with cases of the weak concept, would be something doable only by a third person. On the classical definition of knowledge, then, the subject of tacit knowing sometimes has itself no such thing as explicit propositional knowledge (neither is it able to express its competence in true propositions nor can it give reasons for those propositions). Other persons, however, would indeed possess knowledge – knowledge that adequately and completely describes the subject's actions. Herein we can see the separation between explicit knowledge and praxis. Both can exist totally independently from each other. But it seems rather implausible not to attribute any kind of knowledge to the agent when the corresponding propositional knowledge – knowledge held by an external observer by meticulously analysing the process of action – depends precisely on the action and the knowing-how of this particular agent.

If we take the example of a cyclist, we can state that as long as she is able to keep herself steady she needs to have some kind of practical knowledge which a physicist can translate into propositions. I am not saying that the cyclist knows about the laws of physics in cycling. What I am claiming is only that she obviously obeys them without knowing them.Footnote ²⁰ She has the competence of riding a bike and therefore she knows how to ride a bike.Footnote ²¹

Coming back to the positions mentioned at the beginning, which claim to give a general definition of knowledge by providing a definition of propositional knowledge (on the assumption that all forms of knowledge could be reduced to propositional knowledge),Footnote ²² we can extract the following necessary conditions for the attribution of knowledge: (i) opinion/belief, (ii) truth, (iii) justifiability (the classical triad)Footnote ²³ as well as (iv) epistemic methodical security.

However, those are not the only conditions brought forth in the discussion: Noam Chomsky's theory of innate universal grammar seems to assume other (obviously less demanding) conditions for the attribution of knowledge. He assumes that the child has “tacit knowledge of these [i.e. linguistic] universals” (Chomsky Reference Chomsky1965: 27; cf. Nagel Reference Nagel1995: 57f.). Nagel criticizes this view and calls this phenomenon “innate capacities that enable a child to acquire knowledge of a language” – a capacity, or competence which is expressly not knowledge (Nagel Reference Nagel1995: 61). Substantial conditions for the attribution of knowledge not fulfilled in Chomsky's theory would be, according to Nagel, (a) the capacity for consciousness and (b) internal evaluability/detachment from experience:Footnote ²⁴

1. (a) According to Nagel, in order to attribute knowledge to the speaker it is not necessary to explicitly formulate the rules that we follow while speaking a language. The speaker can have this knowledge and still never actually be confronted with a propositional form of it. However, it needs to be in principle possible to bring this knowledge to the speaker's mind. When confronted with the corresponding rules, we could not speak of such an internal recognition within the context of Chomsky's universal grammar because of its extremely high level of abstraction (Nagel Reference Nagel1995: 60f.).Footnote ²⁵

2. (b) Nagel diagnoses a lack of justifiability in Chomsky's innate universal grammar. To test if an assertion is correct, we have to rely on the community of speakers. Therefore, truth is constituted only by the speakers’ coherence. However, the mere fact that people behave from birth in a certain way or are convinced of certain assertions does not by far guarantee their truth. Therefore, we could not speak of “a priori or innate knowledge” (Nagel Reference Nagel1995: 63) in this context. Furthermore, Nagel cautiously equates language learning with the process of digestion: like digestion, language learning might be some kind of automatic process (Nagel Reference Nagel1995: 62–4).Footnote ²⁶

Is this kind of criticism enough to disqualify tacit knowing more generally as a form of knowledge? We should beware of making this judgment so quickly, since these conditions do not capture other forms of knowledge, either, like Russell's knowledge by acquaintance, which does not consist of true or false opinions or beliefs, but is usually accepted as a separate form of knowledge.Footnote ²⁷ In the following, I am going to show that certain forms of tacit knowing coincide with Russell's knowledge by description (closely connected with knowledge by acquaintance) and that, therefore, it would be absurd to deny the label of knowledge to at least these forms of tacit knowing.Footnote ²⁸ Furthermore, we will see in part two that tacit knowing plays a crucial part in all the basic divisions of knowledge.

1.3. Does tacit knowing exist?

Before looking at the different divisions of knowledge, we are confronted with a substantial challenge: the claim that tacit knowing simply does not exist. To define and investigate the concept of tacit knowing, of course, we need to show that there is sufficient evidence for its existence.

Numerous empirical cases (masterful musicians, experts in different fields who cannot make their knowledge explicit, etc.)Footnote ²⁹ already show that tacit knowing as a phenomenon does indeed exist. Interestingly, Polanyi uses a passage from Plato's Meno to support his claim that tacit knowing exists. The Meno shows us that we already possess innate (tacit) knowing of the Forms and that we simply need to reactivate it via recollection (anamnêsis).Footnote ³⁰

In the dialogue, Socrates provides evidence for this thesis by asking a slave for the solution to a geometrical problem (how to find the length of a side of a square when you double it). The slave has not been taught geometry (Meno 85d9-e6), does not give the correct answer at the beginning, but through Socrates's elenchos does come to the right (explicit) solution.Footnote ³¹

Empirical examples, however, seem to me better evidence for tacit knowing than the example from Plato's Meno since the passage is not ideal to support Polanyi's thesis as a whole. To sum up the position of the Meno, we actually have the following states: (1) the state before reactivating our innate knowledge (dormant, ‘inactive’ true beliefs),Footnote ³² (2) an intermediate ‘journey’ (rather a process than a state, namely the process of recollection) which helps the slave finally to arrive at (3) the state after recollection (explicit knowledge). The Meno works perfectly to support Polanyi's thesis that “we can know things, and important things, that we cannot tell” (Polanyi Reference Polanyi1966: 22),Footnote ³³ and that there is an intermediate realm between (1) and (3).Footnote ³⁴ However, what seems to be lacking in Plato's account (but to be substantial for Polanyi's theory) is the ‘hint’ or “intimation of something hidden” (Polanyi Reference Polanyi1966: 22f.), a “tacit foreknowledge of yet undiscovered things” (Polanyi Reference Polanyi1966: 23, 22f.). If tacit knowing is present it always manifests itself somehow (as some kind of foreknowledge or as expertise, etc.; see also Neuweg's definition mentioned in section 1.1). In the Meno, there is no real state of ignorance, at least not in the strict sense. What looks like ignorance turns out to be simply true beliefs in an inactive or dormant state. If we take these inactive true beliefs as instances of Polanyi's tacit knowing we would find ourselves in the strange situation of having hidden knowledge which is hidden simply too well. We would always need some wise person who knows that we have this hidden knowledge buried within us to draw it out of us. Otherwise, it would probably stay hidden forever. In state (1) the slave is not at all conscious of his hidden knowledge nor is he able to apply it. Neither does he come up with a correct answer nor does he indicate in any way the correct answer which he is not able to make explicit. Neither in the first state nor in the transition to (3) is there any evidence for tacit knowing (the hidden knowledge only comes to the fore through the Socratic method and thereby becomes explicit).Footnote ³⁵ It is not the case that the slave already understands something (like the case of pattern recognition) or that he is acting competently (like the case of cycling) without being able to explain it or to put it into words (nor is this the case in the intermediate stageFootnote ³⁶). Exactly this, however, seems to be characteristic for tacit knowing if we follow Polanyi (and also Neuweg).Footnote ³⁷ To conclude, it seems more sensible to base this investigation on the contemporary empirical findings that show the presence of something which we could call tacit knowing – and only partly on Plato's exposition in the Meno since this dialogue undoubtedly provides us with an important aspect of tacit knowing, but not with the fully fleshed out concept.Footnote ³⁸

2.1. Knowing-that

What do we mean when we speak of tacit knowing-that? Usually, we are talking about “knowledge taken for granted” and of which we are not even necessarily conscious (Neuweg Reference Neuweg, Fischer, Boreham and Nyhan2004b: 139), such as information resulting from our complete (cultural) background and environment which is consolidated in our minds (Neuweg Reference Neuweg, Fischer, Boreham and Nyhan2004b: 139). Is this kind of knowledge non-formalizable knowledge, and does it therefore represent the strong concept of tacit knowing? Not necessarily. If a certain knowing-that is required in a certain situation, and we can provide this knowing-that, it has obviously already been inside us tacitly. It only becomes apparent in its application (e.g. presupposing gravity, even before the actual law was formulated – on the basis of this assumption, we are careful when confronted with great heights and we can explain ourselves if required). Therefore, fundamental assumptions which do not even have to (but can) be present in us as (lost or unconscious) firm beliefs form part of tacit knowing-that. Maybe we could take Searle's “Background presuppositions” (Searle Reference Searle1992: 186)Footnote ⁴⁰ as forms of tacit knowing-that but also unconscious beliefs.Footnote ⁴¹

However, there also seem to be some other, less fundamental cases of tacit knowing-that. This form must not be confused with ordinary knowledge of facts which might not be present in our minds at the moment, such as historical knowledge acquired at school but to which we do not presently have access. Taking part in a quiz we still pick the right answer – with much uncertainty since this knowledge has been present in us only tacitly. This obviously seems to be a case of knowing-that which we have almost completely forgotten. Therefore, it is much harder to bring it back to our conscious mind.Footnote ⁴²

2.2. Knowing-how

Tacit knowing-how seems to be the most prominent form of tacit knowing or at least the form in which tacit knowing shows itself most clearly. We are talking about expertise, or competence which cannot be made explicit by the subject (Neuweg Reference Neuweg, Fischer, Boreham and Nyhan2004b: 138f.). It can be found in the strong as well as in the weak form (e.g. physical laws of cycling – these can be made explicit, but normally not by the subject; for this example, see Polanyi Reference Polanyi1962: 49f.). We have to ask ourselves, however, if in the end tacit knowing-how can always (somewhere in the distant future when we will have better measuring methods) be given a complete account (from a third-person-view).Footnote ⁴³

Non-practical forms of tacit knowing also fall under this rubric, like knowing what a melody sounds likeFootnote ⁴⁴ or what a colour looks like. Similarly, these forms of perceptual knowing cannot be (completely or sufficiently) made explicit, though we can still visualize quite clearly a certain colour before our inner eye.

To sum up, this kind of tacit knowing can be found in various forms of expertise (music, sports, arts, etc.) but also in our basic perceptions.

2.3. Knowledge by acquaintance and knowledge by description

Knowledge by acquaintance, according to Russell, is concerned with (internal and external) sense data. It is direct knowledge of things of which we are “immediately conscious” (Russell Reference Russell2001 [1912]: 25).Footnote ⁴⁵ This kind of knowledge he contrasts with knowledge by description, i.e. indirect knowledge that we form out of sense data (Russell Reference Russell2001 [1912]: 25f., 28).

This form of knowledge shows close kinship with a certain form of tacit knowing: the recognition of patterns, for example in the case of facial recognition, seems to have strong similarity with knowledge by description (we recognize a face out of single sense data). Polanyi himself mentions this example and explains the process as an integration of proximal terms (in this case, single sense data (facial parts) but not all of them necessarily need to be given) to a distal term (the complete face) (Polanyi Reference Polanyi1966: 4f., 9f.). Directly given are single facial parts. Our tacit knowing of the individual characteristics allows us to recognize the face. Therefore, we could talk about indirect knowledge, even though the perception of a face seems to be directly given (because we are not aware of the tacit integration and perceive the complete face directly). We find ourselves in the same situation when perceiving a physical object like a table. We perceive the table as a table and do not deduce the object from characteristics like the table's colour or size (still, this case would be classed as knowledge by description; Russell Reference Russell2001 [1912]: 25f.).

Of course, we need to bear in mind that Russell does not include cases in which we must mentally complete the picture. This, again, can play a significant role in facial recognition. Parts may be missing because the sight of them is impeded. Moreover, we are practically never confronted with the same face twice. Each time a face will have changed (maybe only to a small extent). That does not prevent us from recognizing the faces of persons familiar to us. Russell, however, also includes knowledge about the mental states of other persons within knowledge by description (Russell Reference Russell2001 [1912]: 28).Footnote ⁴⁶

Thus, examples for tacit knowing in this category would be perception of colour and shape,Footnote ⁴⁷ memory (both are cases of knowledge by acquaintance since they all are immediately given),Footnote ⁴⁸ and perception of physical objects (knowledge by description since they are formed out of sense data).

At first sight, basic perceptions can be assigned to knowledge by acquaintance: Via direct perception we “know” the colour red. Simultaneously, this leads to knowing-how since now we also know what the colour red looks like (without being able to sufficiently explain this sense perception).

This first overview shows us that tacit knowing pervades all the basic forms of knowledge. Therefore, we should be careful not to explain away tacit knowing as an epiphenomenon or as a mediocre form of knowledge. This pervasiveness is present in other prominent divisions of knowledge:Footnote ⁴⁹

2.4. Theoretical and practical knowledge

Although tacit knowing often occurs in practical contexts, it is not identical with practical knowledge. It stretches into the theoretical realm as well, i.e. in processes of understanding. We can take the recognition of patterns again as an example. This recognition, first of all, represents an intellectual process. Every time we recognize something (e.g. a face or a pattern of a certain illness), this knowledge is based on tacit knowing to a large degree. Parts are given which we combine into a whole without being able to explain all of these parts or even to list them. Lacking parts are also possibly supplied by us.

Practical knowledge shows a similar structure when we still act intelligently and adequately, even though our data basis might be insufficient or imprecise. In these cases, competence or tacit knowing-how is expressed. Therefore, we could speak of a subdivision of knowing-how, i. e. knowing-how which comes to the fore in practical expertise.

Tacit knowing plays an even more foundational role in theoretical knowledge, however, since all theoretical or explicit knowledge ultimately rests on tacit roots. We could not understand any theoretical explicit statement without tacit presuppositions,Footnote ⁵⁰ like the understanding of the context or the theory which we use to arrive at this statement. We focus on the object of our investigation, whereas the theory is instrumental – in the sense that we do not scrutinize it as theory but use it to conduct our investigation (Polanyi Reference Polanyi1962: 59–62; Neuweg Reference Neuweg2004a: 334–40). In fact, not even language itself, which we use to explicitly formulate our knowledge is devoid of a tacit component: namely, meaning. When we explain a theory, for example, we do not explain every word in the explanation. Accordingly, Polanyi states on various occasions that “[a]ll knowledge is … either tacit or rooted in tacit knowing” (Polanyi and Prosch Reference Polanyi and Prosch1975: 61);Footnote ⁵¹ “strictly explicit knowledge” would even be “self-contradictory” (Polanyi Reference Polanyi and Grene1969: 195) and “unthinkable” (Polanyi Reference Polanyi and Grene1969: 144) since the rules of how to apply or understand it remain tacit. We could, principally, put into explicit terms the rules for understanding a certain sentence by referring to the different words and then referring to their meaning and so on. The point is, however, that this would lead to an infinite regress (Polanyi and Prosch Reference Polanyi and Prosch1975: 61).Footnote ⁵² If we do not want to go on forever in explaining the meaning of a sentence we just uttered, we simply have to stop explicitly spelling out the meaning of the words used in our explanations and accept them as their tacit component. Using language is, according to Polanyi and Prosch, a “tacit operation” (Polanyi and Prosch Reference Polanyi and Prosch1975: 60).Footnote ⁵³ They do not stop there but extend this claim to “all other explicit thought” (Polanyi and Prosch Reference Polanyi and Prosch1975: 60) and take measurement as an example. Everything we measure or state in mathematical formulae is understood only by tacitly referring to the meaning of what the measure or the formula stand for (Polanyi and Prosch Reference Polanyi and Prosch1975: 60f.; Polanyi Reference Polanyi and Grene1969: 179). Consequently, explicit theoretical knowledge can never make explicit everything which is needed to understand it. We can choose to explain, for example, either the chemical structure of water or the words and grammar used in that explanation (which would transform our statement to a linguistic one).

It seems rather surprising, in fact, that we often still assume theoretical knowledge to be entirely explicit knowledge. Already in Wittgenstein, and later in Davidson, we have emphasis on implicit meaning, as Barry Stroud's comparison between the two nicely shows. We cannot understand sentences if we do not already know what is meant by the different components of the sentence.Footnote ⁵⁴

2.5. Technê and epistêmê

Starting from a general definition of technê (“application-oriented expert knowledge or some practical professional skill – the reason why this expression can be used generally for artistic, craftsmanship, practical, scientific or philosophical disciplines” (Horn Reference Horn, Horn and Rapp2008), those forms of tacit knowing located in the practical realm seem to be paradigmatic cases of technai. Aristotelian text passages manifest that technê designates that “which rules the movement of an organon” (Horn Reference Horn, Horn and Rapp2008). The instrument also plays an important role for Polanyi: e.g., a blind person controls her instrument (a stick) by indwelling it and not as such but as an instrument for something (recognizing the environment). Through this indwelling, the stick becomes the proximal term (Polanyi Reference Polanyi1966: 12f., 16f.). Therefore, we could conclude that when skilfully using an instrument the person possesses technê or tacit knowing.Footnote ⁵⁵

Drawing a sharp distinction from epistêmê also seems very plausible since we are not dealing with classical theoretical knowledge here (knowledge which can be sufficiently explained and justified).Footnote ⁵⁶ On a closer look, the binary division between technê and epistêmê is far too simple, however. Tacit knowing is more than mere technê. Even if it might lack in formalizability (at least in the strong form) and therefore is to be excluded from classical scientific knowledge (epistêmê),Footnote ⁵⁷ it still intersects with Aristotelian phronêsis. The virtue of phronêsis “belongs to the intellectual (dianoetic) virtues” (Elm Reference Elm, Horn and Rapp2008) and at the same time designates practical knowledge. It is not concerned with the unchanging, eternal realm, but with things which can change. As in the case of tacit knowing, situatedness plays a significant role. When I possess tacit knowing or the virtue of phronêsis, I act flexibly and skilfully according to the particular case – at least in the case of phronêsis by using general knowledgeFootnote ⁵⁸ as a guiding principle for the particular case (Elm Reference Elm, Horn and Rapp2008).Footnote ⁵⁹

Furthermore, if we consider again the tacit roots of theoretical knowledge what has been said in section 2.4 can equally apply to the concept of epistêmê. If we understand epistêmê as true justified belief we do not also provide an explanation of the meaning of the words used in the formulation of this belief.

2.6. Procedural and declarative knowledge

If we follow Jeremy Fantl's definitions, declarative knowledge is explicit knowledge which can be brought to consciousness whereas procedural knowledge is “knowledge that is manifested in the performance of a skill” (Fantl Reference Fantl2021: section 1.3). Thus, it seems clear that tacit knowing itself is not declarative, although the components of the declaration are tacit in the sense explained above (see section 2.4).

The definition of procedural knowledge is wide enough as to include tacit knowing. However, we need to take into account that tacit knowing does not designate automatic applications of procedures, but dynamic reactions to different circumstances.Footnote ⁶⁰ Tacit knowing, therefore, does not fully coincide with either of these forms of knowledge. Tacit knowing is more flexible than procedural knowledge and cannot be put into rigid, explicit terms. However, that does not mean it cannot be found on a continuum between procedural and declarative knowledge.Footnote ⁶¹ Tacit knowing could be described as non-rigid or dynamic procedural knowledge.