Having a Reason

As I have mentioned in a couple of places, I am not too happy with my answer in the Embrace the Void podcast concerning the limitations of "Having a Reason". So, I wrote up a more complete answer more to my liking.

To "have a reason" to do X is to have a desire that would be fulfilled by doing X. If a person says, "Agent has a reason to do X" then either "Agent has a desire that would be served by Agent doing X" or "Agent has a reason" is false.

When I say "Agent has a desire that would be served," I mean an actual desire that would be fulfilled. The agent might think she has a reason and be wrong. Dead wrong, if she makes a particularly serious mistake. She might think that she has a reason to take homeopathic medicine, but she does not. She may think that she has no reason to be concerned about who wins the election, and be wrong. This is because she may be wrong about what serves her desires.

The idea that to have a reason to perform an action is to have a desire that would be served by performing that action actually comes from David Hume.

No other type of reason exists. If a person claims that an Agent has a reason to do something, and the agent does not have a desire that would be served by doing that thing, then the statement that he has a reason is false.

It is not logically false. That is to say, it is logically possible that other types of reasons exist. This is true in the same way that it is logically possible that ghosts exist. They do not exist, as a matter of fact. But they are not inconceivable.

Here, I think I have been accused of blowing off these other types of reasons a bit too quickly - as if I need to do more work.

However, I can't do more work. This is now "nonexistence" works. The only evidence for nonexistence is that there is no evidence of existence. That is to say, I must wait for somebody who asserts existence to say, "Here is my reason for thinking this must exist" and refute it. The ball is in their court, as it were.

In this sense, the argument against the existence of other types of reasons is like the argument against the existence of ghosts, angels, the Loch Ness Monster, free will, and the like. I can do no more here than "all that I can do".

The argument for the existence of desires is pretty straight forward. We need desires to explain intentional action. Intentional actions are observable phenomenon that need an explanation, and the explanation includes desires. The "desire that p" provides the agent with a motivating reason to act so as to realize a state of affairs where 'p' is true, and we can see people acting on reasons.

I don't know of an argument for the existence of any other types of reasons.