A term mostly applied to the distinction between ‘relations of ideas’ and ‘matters of fact’, a distinction central to Hume’s epistemology and one that he wields with great argumentative effect. It is more rarely a name sometimes given to the dilemma that either our actions are determined, in which case we are not responsible for them, or they are the result of random events, in which case we are also not responsible for them. See also dilemma of determinism, free will, matter of fact.