Inference and Rational Commitment

What is it that explains the rationality of transitions in thought? It is natural to think that any such explanation will need to advert to at least two interrelated issues. The first has to do with what is constitutive of the validity of a transition, and the second with our actual practice of making inferential transitions. Many accounts attempt to deal with both issues simultaneously by showing how it is that a thinker, competent with a logical expression N, grasps the content of N in such a way as to make their inferential practices with N rational. Advocates of the conceptualist approach to rationality, such as Christopher Peacocke, attempt to account for this relationship by grounding rationality in concept possession. This paper argues against this account, because (a) it cannot provide an appropriate way of distinguishing true and false normative commitments; (b) typing a token cognitive state as a propositional attitude does not depend upon any specific set of conditions that thinkers must instantiate as a matter of metaphysical necessity. In response, I briefly offer suggestions towards an alternative, and psychologically tractable, account of rational commitment by resisting the tendency to run-together the two issues.