  The other influence was Kantian. From H.J. Paton’s lectures on Kant, and articles by Reginald Jackson, he learnt that imperatives fall within the realm of reason. This led him into a study of imperative logic, a topic already being explored in Scandinavia (especially by Alf Ross), but unfamiliar in Britain. In his first published article, “Imperative Sentences” (1949), in his essay “Practical Reason” entered for the T.H. Green Moral Philosophy prize in 1950, and in his first book, The Language of Morals (1952), he explored the possibilities of inferring imperative conclusions from imperative, or a combination of imperative and indicative, premises.