How to understand internalism

Internalism about practical reasons claims that there is a necessary connection between what an agent has reason to do and what he would be motivated to do if he were in privileged or optimal conditions. Internalism is traditionally supported by the claim that it alone can capture two (supposed) conditions of adequacy for any theory of practical reasons, that reasons must be capable of justifying actions, and that reasons must be capable of explaining intentional acts. Robert Johnson (The Philosophical Quarterly, 49 (1999), pp. 53–71) has argued that versions of internalism which avoid obvious problems nevertheless fail to capture both conditions. I argue that Johnson's criticisms rest upon a misinterpretation of the 'explanatory condition', and I proceed to formulate a version of internalism which will allow practical reasons to have both justificatory and explanatory force