Reply to Holmen on Hornsby

I wish to respond to Heine Holmen’s very insightful analysis of Jennifer Hornsby’s paper, “Knowledge, Belief and Reasons for Acting”. Since Holmen already does a fine job adumbrating Hornsby’s position (see here), I will skip the summary and jump right into the analysis.

Let me begin by laying my philosophical cards on the table. I am very sympathetic with Hornsby’s claim that knowledge is a reason for acting. However, I believe Hornsby’s account suffers because of her failure to distinguish between (what may be referred to as) explanatory and justificatory reasons. Explanatory reasons (or what I sometimes prefer to call “motive-giving explanations”) have to do with our attempt to make sense of or explain the purposive activity of intentional agents (rational and non-rational alike). By contrast, justificatory reasons have to do with our attempt to ascertain whether or not the actions of an intentional agent are rationally recommended (and is therefore only applicable to agents with rational capacities). Both explanatory and justificatory reasons are normative (since they both allow for the possibility of error); but while the former answers to a why question (vis-a-vis the actions of any intentional agent) the latter answers to a should question (vis-a-vis the actions of a rational agent).

Note: I define a rational agent as an intentional agent with linguistic abilities.

According to Hornsby, “acting for reasons does not come into play unless the agent has knowledge” (I am here quoting Holmen’s summary of Hornsby’s position). Here, Hornsby clearly has justificatory reasons in mind, for we often are able to make perfect sense of the actions of agents who act from mere belief (including false ones) rather than knowledge. For example, suppose I’m playing catch with my dog in the park. I pretend to throw the ball, and the dog runs over to the place where the ball would have landed (had I thrown it) and proceeds to investigate the location(sniffing around without success). I can explain or make sense of the dog’s behaviour by observing that the dog believes that I threw the ball. The fact that I did not throw the ball (and that the dog’s belief is therefore false) does nothing to undermine my ability to explain the dog’s actions. Thus, as far as explanatory reasons are concerned, I am perfectly capable of making sense of the dog’s actions by simply referring to the dog’s beliefs. No recourse to talk of knowledge is required (in fact, since we are talking about a non-linguistic animal, some would argue that talk of knowledge is not even appropriate). Finally, it is worth emphasising that since there are correctness conditions attaching to the dog’s behaviour (i.e., the dog get’s things wrong when it believes I threw the ball), such explanations remain normative in nature. (I am here assuming that the possibility of getting things wrong is necessary and sufficient for normativity.) Thus, we arrive at my earlier claims that explanatory reasons do not require knowledge, are normative, and can be applied to non-linguistic animals.

If I am right, then Hornsby’s requirement that acting for reasons implicates knowledge is limited to justificatory reasons. Consequently, she errs by assuming that what may be a perfectly good point (i.e., that having a justificatory reason for acting requires knowledge) applies to explanatory reasons as well. Holmen observes Hornsby’s indebtedness to Williamson on precisely this score:

Hornsby seems to start out by picking up a clue from Williamson’s suggestion (2000, p. 62) that knowledge sometimes must figure in the best explanation for why some agent F-d. According to him, attributions of knowledge may be a better predictor for determining someone’s actions by lending more probability to a certain way of conduct. The intuitive example is the rational burglar who risks a lot by searching the whole building for a valuable diamond.

Holmen goes on to summarise what he takes to be the upshot of Williamson’s burglar example:

The only way to understand why a burglar would take such a risk is, according to Williamson, by attributing her with the knowledge that the diamond is in the building. Otherwise it would be hard to explain why she apparently disregards evidence to the contrary—i.e. as the time goes and her search is not successful—on pain of diminishing her rationality (like declaring her to be just plain stubborn, insensitive to evidence etc.).

I am sceptical about the above argument. It seems to me that what is really doing the work in the burglar example is the certainty or conviction with which the relevant beliefs are held, rather than the fact that the beliefs are true (or, a fortiori, that the agent has knowledge). First, consider the burglar’s psycho-physical doppelganger who is just as convinced that there is a diamond in the building (based on the same body of evidence), but does not have knowledge because (unknown to him) a ridiculously improbably quantum occurrence has transformed the diamond into a block of coal. We would not expect the behaviour of the doppelganger to diverge from that of his twin just because his justified belief turns out (quite improbably) to be false. In short, if we stipulate that the level of certainty is identical in both cases, this is sufficient to explain or make sense of why each respective burglar persists in his search for the diamond. It seems to me that the fact that in one case the justified belief happens to be false (thus baring the agent of knowledge) in no way reduces our ability to make sense of or explain the agent’s behaviour.

It may be objected that while we can still make sense of or explain the doppelganger’s actions in light of his firm conviction, we would also be inclined to regard him as rationally irresponsible for having such a firm conviction, given that he lacks knowledge. But even if we grant that this is so (and I have my misgivings) the question is no longer one of making sense or explaining why the burglar did what he did. Instead, it has become one of his rational standing. In other words, this is to switch our focus from one of motivation (why did he do what he did) to one of justification (is he justified in doing what he did). Since belief-desire explanations (as I understand them) are only concerned with the former, the burglar argument is simply changing the subject of debate. A similar point can be made with regards to Hornsby’s knowledge requirement. Hornsby endorses the following claim:

(E) Where ‘x Φ-d because p’ gives a reason-explanation: x Φ-d because p iff x Φ-d because x knew that p.

On the view I have been urging, (E) is true so long as we understand a “reason-explanation” as a justificatory rather than explanatory explanation. Since the latter (but not the former) is a necessary condition for intentional explanation, the truth of (E) is irrelevant to the type of intentional explanation that the belief-desire theorist is concerned with. Holmen, however, advances a slightly different criticism of (E)—namely, that it entails a version of the KK principle:

I think I see a problem with (E): it seems to be a version of the KK principle and thus leads one to the absurd consequence that follows when one applies an S4 model for the accessibility relation that operates on the epistemic operator.

However, it is not clear that (E) entails any such control principle. For example, consider a rudimentary reliabilist account of knowledge; one according to which the naive chicken-sexer counts as knowing the sex of the chicks she reliably sorts. Let us suppose further that the naive chicken-sexer, being naive, does not know that she knows the sex of the chicks. In short, her knowledge is strictly of the first order. According to (E), if the naive chicken-sexer sorts some male chick M as male because she knows that M is male, then she sorts M as male for a reason. This remains true even though she does not know that she knows the sex of the chick. Thus, (E) does not entail the KK principle.

In summary, while I share both Holmen’s sympathy for and critical attitude towards Hornsby’s knowledge requirement for reasonable action, I do so for very different reasons. I believe Hornsby’s analysis goes wrong due to a conflation of explanatory and justificatory reasons. While Hornsby’s claims may be be true of justificatory reasons, they are not true of the type of explanatory reasons that constitute the bread and butter of the belief-desire theorist. Moreover, I have argued that Holmen’s primary objection to Hornsby’s theory—i.e., that it commits her to an implausible KK principle—misses its mark.