  How, more generally, should we understand the relation between structural requirements and our reasons for action and belief? One view, held in common by Humeans and by some Kantian constructivists (see sec. 2 above), is that reasons are fundamentally derivative from rational requirements. What one has reason to do, on this view, is what one would desire or intend to do if one was fully rational (i.e. fully in compliance with the wide-scope structural requirements that govern one’s attitudes in combination).