Thursday 18 June 2009

Reply to Holmen on Williamson

In his review of Jennifer Hornsby’s “Belief and Reasons for Acting”, Holmen briefly considers Williamson’s example of the burglar who persists in searching for a diamond in a house at great risk of being caught. Holmen takes the burglar example to establish the following claim:
[K]nowledge sometimes must figure in the best explanation for why some agent F-d. According to him [Williamson], attributions of knowledge may be a better predictor for determining someone’s actions by lending more probability to a certain way of conduct.
Roughly, the idea is supposed to be that the burglar’s persistence can only be satisfactorily explained by attributing him with knowledge. Consequently, it is alleged that knowledge attribution allows us to better explain or predict what the burglar would do.

In my previous post, I expressed reservations about whether Williamson’s burglar example establishes the conclusion Holmen claims it does. I consider the burglar’s psychophysical doppelgänger, who displays the same level of psychological conviction and engages in the same exact behaviour, but who nevertheless lacks knowledge because his belief has been rendered false by a highly improbably quantum occurrence. I maintain that so long as we keep his level of psychological conviction the same as that of the original burglar, we are equally able to explain (i.e., make sense of) and predict his behaviour. The upshot is that knowledge attribution is not necessary for a satisfactory explanation of the burglar’s conduct. What knowledge attribution adds (if anything at all) is not explanatory or predictive power, but rather a justificatory dimension—it helps us to understand why the burglar who has knowledge was justified in his conduct.

In his follow-up post, "Knowledge in Explanation: A reply to Avery Archer", Holmen attempts to sidestep my criticism by arguing that the fact that we can explain an agent’s conduct even when she lacks knowledge does not undermine the claim that knowledge is sometimes necessary for explaining or predicting an agent’s conduct. His point seems to be that, at best, my argument shows that something other than knowledge can explain or cause the burglar’s conduct. Even so, I have not shown that knowledge is not the explanation or cause of the agent’s behaviour in the particular example Williamson posits. Holmen summarises what is problematic about my argument as follows:
Avery's case is more like saying that "Shakespeare did not write Macbeth since there is a doppelgänger case where Macbeth gets written but by Marlowe." And even granted the presence of such a case Shakespeare surely wrote Macbeth and is the cause of Macbeth's existence. Likewise, there could be dozens of cases where the burglar acts in the same way but for other reasons than that he knew P. They say nothing whatsoever about whether Kp is the cause in our case for his behaviour.
However, it seems to me that Holmen mischaracterises the dialectical context in which my objection to the burglar example is articulated. He depicts my argument as attempting to establish a positive conclusion when the conclusion it seeks to establish is purely negative. This point may be illustrated by considering the following single-premise argument:
(1) The biological complexity we observe can only be satisfactorily explained by the existence of a Divine designer

(2) Therefore, there is a Divine designer

We may effectively refute (1)-(2) if it could be shown that:
(1*) The biological complexity we observe can be satisfactorily explained by natural selection.
If true, (1*) impugns (1)-(2) by revealing (1) to be false. However, (1*) only establishes the negative conclusion that (1)-(2) fails to establish its conclusion. It is not (nor should it be taken to be) a positive argument showing that (2) is false. For example, the following is clearly a bad argument:
(1*) The biological complexity we observe can be satisfactorily explained by natural selection.

(2*) Therefore, there is no Divine designer.
The lesson is that the same consideration can be effective in a negative argument (i.e., one intended to show that a specific argument fails to establish its conclusion) but ineffective in a positive argument against that same conclusion. It is therefore important to get clear on the aim of an argument (whether it is negative or positive) before one can evaluate its cogency. Since my objection only targets the efficacy of Williamson’s burglar argument it is clearly a negative argument.

Now Holmen’s point seems to be that my claim that beliefs are equally able to explain or predict an agent’s conduct does not entail that knowledge is not a cause. This is of course true if one assumes that I am offering a positive argument in which the conclusion “knowledge is not a cause” is supposed to directly follow from the claim that “things besides knowledge may also be causes”. But to construe my argument along these lines would be to overlook the dialectical fact that I am simply challenging one of the premises in Williamson’s argument (i.e., a purely negative endeavor). To see that this is so, we may summarise Williamson’s burglar example in terms of the following single-premise argument:
(3) The burglar’s conduct can only be satisfactorily explained by attributing him with knowledge.

(4) Therefore, knowledge is sometimes necessary for a satisfactory explanation of an agent’s conduct.
What Williamson’s burglar example alleges to show is that there are certain kinds of conduct (such as the burglar's persistence in the face of countervailing evidence) that simply cannot be satisfactorily explained without attributing knowledge to the relevant agent. (In this regard, his argument is analogous to the creationist who insists that a Divine designer is the only satisfactory explanation of the observed biological complexity.) Construed along these lines, all one needs to do in order to impugn Williamson’s argument is to show that the very same conduct can be satisfactorily explained without attributing knowledge. Since the agent’s conduct is one of the things that is held fixed between the burglar and his doppelgänger, then our ability to explain the doppelgänger’s conduct without attributing knowledge to him shows that knowledge attribution is not necessary to satisfactorily explain or predict the original burglar’s conduct. Thus, we arrive at my counterclaim:
(3*) The burglar’s conduct can be satisfactorily explained by attributing to him a belief with the appropriate level of psychological conviction.
If true, (3*) shows that (3)-(4) fails to establish its conclusion by revealing (3) to be false.

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