  Externalists often appeal to the parallels between practical reasons (reasons for action) and epistemic or theoretical reasons (or reasons for belief) to make their case against certain forms of internalism, particularly the Humean Theory of Reasons (Millgram 1996). They seem to be different species of the same genus: while practical reasons are facts that support or justify certain actions, theoretical reasons are facts that support or justify certain beliefs. Both sorts of reasons are subsumable under the class of normative reasons, or facts that support certain behaviors.