Two natural ideas we have about justification are that we are justified by basing our beliefs on good reasons, rather than wishful thinking or blind prejudice, and that justification makes our beliefs objectively likely to be true. Despite their appeal, respecting both of these ideas is impossible if we think that one's reasons for belief are determined entirely by one's psychological states, such as one's beliefs and experiences, and not by how the world is around one. If one's reasons are isolated from the world, it seems that they could not make our beliefs likely to be true.

This is why the debate between epistemic internalists, who think that justification is determined just by states of the believer, and externalists, who deny this, seems so intractable. Internalists are motivated by the intuition that justification is determined by the subject's reasons for belief, whereas externalists are motivated by the intuition that justification makes our beliefs objectively likely to be true.

I argue that the key to resolving this dispute is to reject the view that one's reasons are determined entirely by one's psychological states in favor of the view that one's reasons are facts - including facts of the world around one. We can then accept both the idea that justification is a matter of the subject's reasons for belief and the idea that justification makes one's beliefs objectively likely to be true. On this view one's reasons (the facts of the world around us) can make one's beliefs likely to be true. The result is a theory of justification that captures the motivations both of traditional forms of internalism and traditional forms of externalism, while avoiding the characteristic problems those views face.