Reasons and causes

Imagine being told that someone is doing something for a reason. Perhaps they are reading a spy novel, and we are told that their reason for doing so is that they desire to read something exciting and believe that spy novels are indeed exciting. We then have an explanation of the agent’s action in terms of the person’s reasons. Those who believe that reasons are causes think that such explanations have two important features. First, they enable us to make sense of what happens. Reading a spy novel is the rational thing for an agent to do if they have that particular desire and belief. Second, such explanations tell us about the causal origins of what happens. They tell us that the desires and beliefs that allow us to make sense of actions cause those actions as well.

The idea that reasons are causes has evident appeal. We ordinarily suppose that our reasons make a difference to what we do. In the case just described, for example, we ordinarily suppose that had the agent had appropriately different desires and beliefs then they would have acted differently: had the person desired to read something romantic instead of exciting, or had the person believed that spy novels are not exciting, a spy novel would not have been chosen. But if what they desire and believe makes a difference to what they do then the desires and beliefs that are those reasons must, it seems, be the cause of the person’s actions.

Despite its evident appeal, however, the view that reasons are causes is not without its difficulties. These all arise because of the manifest differences between explanations in terms of reasons and causal explanations.