If a person is thirsty, and has a false belief that a glass is filled with clean water, does he have a reason to drink from the glass?
My answer is, "Obviously not. The agent has a false beliefs that he has reason to drink from the glass."
This seems to be an item of contention among philosophers, and I am trying to figure out why.
Bernard Williams discusses this in his highly influential article on internal and external reasons (Williams, B., 1979. “Internal and External Reasons,” reprinted in Moral Luck, Cambridge: Cambridge University Press, 1981, 101–13).
He began with:
A has a reason to φ iff A has some desire the satisfaction of which will be served by his φ-ing
He then replaced 'desires' with 'elements of an agent's subjective motivational set S' for reasons to be discussed in a future post.
He then wrote:
An internal reason statement is falsified by the absence of some appropriate element from S.That is to say, if it is not the case that A has an element in his motivational set that is served by his φ-ing, then he has no (internal) reason to φ.
Williams then discusses a potential objection to this based on the problem of false belief. The example he uses is very similar to the example I often used and mentioned above. I will not put it beyond the realm of possibility that I picked up this example by reading Williams’ article several years ago and forgetting about it.
Anyway, in Williams example:
The agent believes that this stuff is gin, when it is in fact petrol. He wants a gin and tonic. Has he reason, or a reason, to mix this stuff with tonic and drink it?
Answer: No. He falsely believes that he has a reason to mix this stuff with tonic. He does not actually have a reason to do so.
Williams wants to suggest that there is a problem with this answer. The problem comes from the fact that we still explain the agent’s action in terms of desires (or ‘elements of an agent’s subjective motivational set’) and beliefs. The only difference is that a belief is false.
However, that does not alter the nature of the explanation.
The difference between false and true beliefs on an agent’s part cannot alter the form of the explanation which will be appropriate to his actions.
This is true. However, we still need to distinguish between a successful action – one that reaches its goal – and one that does not.
When an airplane crashes, investigators use the same terms to explain the crash that they use for a successful flight - such things as altitude, air speed, thrust, lift, and drag. This gives us no reason to bury the fact that the airplane crashed and to write about the event as if it were a successful flight. It still crashed.
In the case where the agent drinks the petrol, we need to talk about the act as an intentional act - one that came from the agent's beliefs and desires. However, one of the most important facts about this intentional action was its failure. The cause of that failure is false belief. We mark it as a failed act and explain the failure by saying that the agent did not have the reason to mix the stuff with the tonic that he thought he had.
I predict that blurring the distinction between successful and unsuccessful actions – what the agent was aiming at, and what the agent actually got – what the agent actually had reason to do, and what the agent falsely believed he had reason to do.
Williams comes to the same conclusion. Consequently, he writes:
A member of S, D, will not give A a reason for φ-ing if either the existence of D is dependent on false belief, or A’s belief in the relevance of φ-ing is false.