 In his earliest work Prichard supposes that principles specify distinct obligations, e.g. those of telling the truth, educating one’s children, serving one’s country. It did not take him long to see that, so understood, pretty well any collection of principles is going to lead to contradiction and incoherence. He then moved to what looks like a form of what we now know best as Ross’s theory of prima facie duties. On this understanding, a principle specifies what Prichard calls a ‘claim’ on us, for example that we serve our country – but all such claims can be defeated by more pressing claims to do something else, such as care for our aging mother. Prichard’s version seems to differ from Ross’s, however, at least if we are to trust a letter he wrote to Ross in 1932 (to be found in MacAdam, 286–7). Ross thinks that duty proper, as he calls it, is a quite different sort of thing from a prima facie duty; the notion of ‘duty’ in ‘prima facie duty’ is a different notion from that in ‘duty proper’. Prichard, by contrast, thinks of this as incoherent, and opts instead for the view that, expressed in terms of ‘ought’, maintains that, faced with a moral difficulty, there will be different actions each of which in some respect I ought to do (this is the prima facie ought) and of those one will be the action which I most ought to do, my duty proper. On this picture there is no great divide between the ‘ought’ of duty proper and the ‘ought’ of prima facie duty.