The argument of this paper rests on the distinction between two types of what are, loosely speaking, logical claims: A general (speaker-independent) claim that some favoured principle of inference is both truth-preserving, and consistent with certain others. A claim by a particular speaker that he/she has reasonable deductive grounds for concluding that some particular statement is true. The first is a matter of pure logic—a question of what (allegedly) follows from what. The second is a matter of epistemic logic—a question (...) of whether someone has, or more generally, whether there are, reasonable deductive grounds for concluding that something is the case. I shall argue that this distinction has a crucial bearing on the disagreement between classical logicians and non-classical logicians, which is essentially a disagreement about inferential behaviour. The argument is laid out in a manner designed to maximise the chances of any errors being detected. The paper concludes with some considerations of the relevance of relevant logic to the psychologist investigating inference behaviour. (shrink)
