Abstract

How does evidence figure into the reasoning of an agent? This is an intricate philosophical problem but also one we all encounter in our daily lives. In this chapter, we identify the problem and outline a possible solution to it. The problem arises, because the fact that it is up to us whether we do something makes a difference to how we should think of the evidence concerning whether we will actually do it. Otherwise we regard something that is up to us as if it were not: We regard something that is up to us as if it were the outcome of a lottery. Nonetheless, we would be wrong to ignore the evidence. Otherwise we could not make a rational decision. In this chapter, we first show that a decision-theoretic approach to this problem cannot succeed. This approach does not explain how we can take evidence into account in practical reasoning without making predictions concerning matters that are up to us. It also gives rise to incoherence between our practical and our theoretical conclusions. We then argue that what is required to solve the problem is recognizing that beliefs about matters that are up to us can be grounded in practical reasoning. We argue that such beliefs are not subject to an evidential norm, because they are not meant to reflect a reality that is independent of them but instead are meant to bring about the reality they represent. Finally, we argue that, even if we are fully rational agents, we will sometimes lack practical knowledge of what we will do. That is because when it is practically rational to do something that will require resolve, we may be in a position to rationally conclude that we will do it, even though we have evidence that there is a non-negligible chance that we won’t. In such cases, our evidence serves as a defeater for our practical knowledge.