Some hold that there is an important disanalogy between justified belief and justified action. When speaking of justified belief, we distinguish between doxastic and propositional justification, where the former obtains when there is propositional justification for the content of the belief, and the belief is properly based on the propositional justification in question. We might distinguish similarly between two kinds of justification in the arena of action, between the action-type being justified and the action-token being justified because it is done for the reasons that justify the action-type.
Here’s the purported disanalogy, however. Arbitrary actions can be justified in the way that is analogous to doxastic justification. Suppose you are choosing what to eat for breakfast, and you’ve got no reason to prefer Wheat Chex to Rice Chex, but arbitrarily choose to eat Wheat Chex. Your action is fully justified, but it need not be based on any reasons for preferring one kind of Chex cereal to the other, since by hypothesis, there are none.
I think this attempt to distinguish the role of reasons and basing in the arena of action from the arena of belief fails. There are reasons for eating Wheat Chex–you like it, it will fill you up, you’ll enjoy the experience, and it won’t cause cancer (we hope). If your eating Wheat Chex is rational, you will be eating the cereal for these reasons. What is not true is that there are reasons to prefer eating Wheat Chex to eating Rice Chex, so your action need not be based on such reasons. In slogan form, we can say that your action must be based on reasons, even if they need not be based on contrastive reasons.
So the difference between action and belief is not that basing is required in the latter but not in the former. It is, rather, that one’s reasons can leave open multiple options in the case of action but perhaps not in the case of belief. That’s the lesson of the Buridan’s Ass paradox: reasons for A-ing need not be reasons that would undergird contrastive explanations (though perhaps I should be pushed a bit on how this could possibly remove the paradoxicality here).
On the issue of optionality for belief, some qualifications are necessary as well. For one thing, one’s evidence can justify your believing p even though it doesn’t discriminate p from rival hypotheses that you’ve never heard of nor considered. But there is a question whether optionality is eliminated in the case of belief even when we restrict the options to those you are aware of. You’re at the zoo, you see a zebra, a believe on that basis that the animal in question is a zebra. But you’re evidence doesn’t reveal that it’s a zebra rather than an elaborate illusion constructed by a mad scientist. So you have no reasons to prefer the zebra hypothesis to the illusion hypothesis, except those relying on background assumptions about prior experiences of this sort (where your reasons in those cases weren’t contrastive reasons). My inclination, however, is to think that the lack of contrastive reasons here doesn’t prevent your belief from being justified.
More generally, if we are impressed with Quine/Duhem point about optionality in theory revision in light of anamolous experimental results, we should be wary of the requirement of basing on contrastive reasons for rational or justified belief. We should avoid describing the options as “choices”, given the voluntarism implicit in that term, but the Q/D point transposed into the context of belief revision implies that there is optionality in belief revision. Even so, the revisions must be based on the evidence in question in order for the new beliefs to be doxastically justified. Perhaps what is not needed is that the beliefs be based on contrastive reasons, reasons that single out that particular belief as the single justified response to the evidence in question.
So the difference between action and belief comes down to this: there is no Buridan’s Ass paradox in the realm of belief, as there is in the realm of action. The optionality available in the realm of belief may not become as stark as that involved in equally attractive actions, but that point doesn’t show that a different account of reasons and basing is appropriate. For the paradoxical situation is just the limit of more common cases in which optionality is present and compossible with justification and proper basing.