R.M. Hare (1919-2002) developed a theory of moral language called Prescriptivism (for a detailed discussion and consideration of the criticisms made of Hare’s position by Philippa Foot go to the Advanced Article in this section), which, in the words of his obituary:

“Though very much a product of its time, in that it was heavily influenced both by the emotivism of A.J. Ayer and C.L. Stevenson, and by the ordinary language philosophy of J.L. Austin and the later Wittgenstein’s view of meaning as use, the book (Language of Morals) was genuinely ground-breaking in its attempt to combine ethical non-cognitivism with constraints of rationality. The essential character of moral discourse consisted, not, as the emotivists had held, in its links with subjective attitudes, but with action; moral judgements were prescriptive, in that they expressed commitments to action on the part of the person uttering them, and at the same time their rationality was assured by their universalisability, ie their property of applying not merely to the person uttering them, but to all similar persons in similar circumstances.”

Hare describes his motivation and purpose in Hare and the Critics:

“It is true of most analytical philosophers, including myself, that they concerned themselves very much with the meanings of words and with logical rigour. This was in reaction from the excesses of the romantics of an earlier generation, and was almost wholly beneficial. It is also true that in this search after clarity and rigour some of them (like Professor Ayer) looked askance at kinds of language, such as moral discourse, which did not seem to them to carry a clear meaning on their face; so they restricted their logical enquiries, as Aristotle (De Int. 17a2) had, to statements of fact expressed in indicative or declarative sentences, and admitting of truth or falsity in some readily explicable sense. There thus arose a school of moral philosophers, the emotivists, who denied that there could be rational moral argument.

In conscious reaction to this tendency, I and a few other analyticals sought to show that an account could be given of the meaning of moral statements which, though not assimilating them to the kind of descriptive statements that logicians had been treating as privileged, nevertheless made it possible for them, and arguments containing them, to be assessed rigorously. I believe that we have succeeded in this. But what I must above all make clear is my motive for wanting to do it.

I entered moral philosophy, and indeed philosophy itself, because I was confronted (as I still am) with serious moral questions, and wanted to answer them in a rational manner. But it was absolutely clear that there was no hope of doing this without first finding a way through the logical difficulties raised by the emotivists. I therefore devoted most of my work in the early stages to these conceptual and linguistic problems But I did not stop being troubled by practical moral issues.”