[I am skeptical about the claim she makes here, but I thought it was interesting. This is from Anscombe’s famous paper “Modern Moral Philosophy”.]
To have a law conception of ethics is to hold that what is needed for conformity with the virtues failure in which is the mark of being bad qua man (and not merely, say, qua craftsman or logician)—that what is needed for this is required by divine law. Naturally it is not possible to have such a conception unless you believe in God as a law-giver; like Jews, Stoics, and Christians. But if such a conception is dominant for many centuries, and then given up, it is a natural result that the concepts of ‘obligation,’ of being bound or required as by a law, should remain though they had lost their root; and if the word ‘ought’ has become invested in certain contexts with with the sense of ‘obligation’, it too will remain to be spoken with a special emphasis and a special feeling in these contexts.
It is as if the notion ‘criminal’ were to remain when criminial law and criminal courts had been abolished and forgotten. A Hume discovering this situation might conclude that there was a special sentiment, expressed by ‘criminal’, which alone gave the word its sense. So Hume discovered the situation in which the notion ‘obligation’ survived, and the word ‘ought’ was invested with that peculiar force having which it is said to be used in a ‘moral’ sense, but in which the belief in divine law had long since been abandoned: for it was substantially given up among Protestants at the time of the Reformation.* The situation, if I am right, was the interesting one of the survival of a concept outside the framework of thought that made it a really intelligible one.
*They did not deny the existence of divine law; but their most characteristic doctrine was that it was given, not to be obeyed, but to show man’s incapacity to obey it, even by grace; and this applied not merely to the ramified presecriptions of the Torah, but to the requirements of ‘natural divine law’. Cf. in this connection the decree of the council of Trent against the teaching that Christ was only to be trusted in as mediator, not obeyed as legislator.