In medieval writers an important distinction was drawn between two applications of the term ‘logica’: there was logica utens, the practice of thinking logically about this or that subject-matter, and there was logica docens, the construction of logical theory. Of course the English word ‘logic’ and its derivative ‘logical’ have a corresponding twofold meaning, and we ignore the distinction at the risk of serious confusion. ‘Logical thought’ may mean thinking that is being commended as orderly, consistent, and consequent, whatever its subject-matter; or it may mean the thinking of logicians about logic, which alas has not always exhibited these virtues. Similarly for ‘teaching logic’: there is trying to get people, by precept and example, to be orderly, consistent, and consequent in their thinking, and there is the endeavour to train logicians for the next generation. In any respectable philosophy department there will be someone teaching logic in the first sense; in my own university there are very many first-year undergraduates who do a course called Reason and Argument with this aim. But we hold that the teacher of such logica utens must himself have a sufficient skill in logica docens if he is to do his job properly; and we undertake the further task of training people in logical theory so that some of them, who have sufficient native ability and motivation, may take up the torch from their teachers.