Is there a nexus between reasons and rationality?

When we say that a subject has attitudes that she is rationally required to have, does that entail that she has those attitudes for reasons? In other words, is there a deep nexus between being rational and responding to reasons? Many have argued that there is. For example, Derek Parfit tells us that 'to be rational is to respond to reasons '. But I am not so sure. I begin by considering this question in the domain of theoretical rationality. The question in this domain is whether, when a subject has the beliefs that she is required to have by the norms of theoretical rationality, she is responding to reasons that there are for having those beliefs. Armed with a moderately clear answer to this question in the theoretical domain, I consider their relationship in the practical domain. When a subject has the desires that she is required to have by the norms of practical rationality, is she responding to reasons that there are for having those desires? Part of the interest of these questions lies in improving our understanding of reasons for action. I will say a little about this towards the end