Testimonial Knowledge-How


There is an emerging skepticism about the existence of testimonial knowledge-how (Hawley in Stud Hist Philos Sci Part A 41(4):387–404, 2010; Poston in Noûs 50(4):865–878, 2016; Carter and Pritchard in Philos Phenomenol Res 91(1):181–199, 2015a) (Hawley does not commit to the impossibility of testimonial knowledge-how. However, she questions whether apparent cases of testimonial knowledge-how will be genuinely testimonial). This is unsurprising since a number of influential approaches to knowledge-how struggle to accommodate testimonial knowledge-how. Nonetheless, this scepticism is misguided. This paper establishes that there are cases of easy testimonial knowledge-how. It is structured as follows: first, a case is presented in which an agent acquires knowledge-how simply by accepting a speaker’s testimony. Second, it is argued that this knowledge-how is genuinely testimonial. Next, Poston’s (2016) arguments against easy testimonial knowledge-how are considered and rejected. The implications of the argument differ for intellectualists and anti-intellectualists about knowledge-how. The intellectualist must reject widespread assumptions about the communicative preconditions for the acquisition of testimonial knowledge. The anti-intellectualist must find a way of accommodating the dependence of knowledge-how on speaker reliability. It is not clear how this can be done.

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  1. 1.

    This form of knowledge-how is closely related to skilled action. If Sally is skilled at φing she must know how to φ. However, the precise relation between non-deontic knowledge-how and skill is controversial (see Pavese 2016 for an overview). In particular, we use non-deontic knowledge-how ascriptions in relation to actions we do not normally think of as involving skill; actions such as changing lightbulbs, or removing malware from a computer. These actions only involve skill in a very weak sense. Thus, I do not take the acquisition of knowledge-how, in the sense we are interested in, to always involve the acquisition of something we might call “skill” in normal circumstances. I take the relevant form of knowledge-how to underlie intentional action more generally, not just the type of intentional action we would normally label as skilful (although I am open to there being a sense of “skill” according to which the ability to remove malware from a computer, or to find some particular house, constitutes a skill; perhaps the sort of skill one might list as such on a CV).

  2. 2.

    See Glick (2012) for a more extensive discussion of the distinction between deontic and non-deontic knowledge-how.

  3. 3.

    Hawley (2010) questions whether cases of apparent testimonial knowledge will be genuinely testimonial by questioning whether such knowledge-how will ever be dependent on the trustworthiness of the speaker.

  4. 4.

    This lends some initial support to the judgement of Carter and Pritchard (2015b) and Stanley (2011) that Charlie does not gain knowledge-how from his instructions. This is because Charlie’s source is arguably not reliable with respect to how one should change light-bulbs.

  5. 5.

    Likewise, Bobby’s knowledge-how in HONEST BOMB seems to be dependent on Alice’s reliability.

  6. 6.

    She gains knowledge-where insofar as she discovers the house is on Bond Street. This exhausts her knowledge-where, she does not know where on Bond Street the house is. So this knowledge-where alone would not allow her to find the house. Moreover, she only knows which house is Wolfgang von Wagner’s insofar as she would be able to distinguish it from the other houses on Bond Street, although at this point she has no acquaintance with any of these houses (as Hawthorne and Manley (2012) point out, it is not clear that acquaintance is required for knowledge-which). These issues will be put to one side.

  7. 7.

    This is not to say that such an agent would automatically gain the ability to perform actions of arbitrary complexity upon fully grasping and understanding the testimony. If an agent learns how to tie a Bimini Twist, yet lacks fingers, they will still not be able to tie the knot. However, they would meet the cognitive preconditions for intelligently and intentionally performing the act: if they met the physical prerequisites they would have the ability. This is, plausibly, one of the factors which sets knowledge-how apart from skill. Skill requires physical capacity, and is lost when the physical capacity is lost. Knowledge-how does not.

  8. 8.

    It might be responded that even if Bill doesn’t have any prior knot tying knowledge-how he is still merely applying old knowledge-how to new cases. Perhaps this would be his knowledge of how to follow instructions and manipulate macroscopic objects with his hands. However, we could say the same of the acquisition of most new knowledge-how, not just through testimony but also through practice, or trial and error. We will be able to write of almost all cases of acquired knowledge-how as cases in which an agent gains the ability to apply old knowledge-how to new cases. This is an implausible result. We are clearly able to gain new knowledge-how.

  9. 9.

    This will depend on the action in question. In some cases the explanation needn’t be particularly involved. TOURIST is such a case. Moreover, in such cases the corresponding inference does not seem problematic: (1) Mark knows how to find Wolfgang von Wagner’s house, (2) Mark told Sally how to find Wolfgang von Wagner’s house, therefore (3) Sally knows how to find Wolfgang von Wagner’s house.

  10. 10.

    This needn’t be experience of riding a bike. It may be experience of something similar, such as riding a tricycle, or experience of separate tasks such as using a stationary exercise bike, and tight rope walking.

  11. 11.

    I have tried to remain neutral between intellectualism and anti-intellectualism whilst diagnosing the problem with Poston’s argument. For a purely intellectualist response see Cath (2017).

  12. 12.

    Similar worries arise for Cath’s (2015) guiding belief analysis, according to which one knows how to φ if one possesses a belief which would reliably guide one in φing.


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Peet, A. Testimonial Knowledge-How. Erkenn 84, 895–912 (2019). https://doi.org/10.1007/s10670-018-9986-7

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