On logics of genus and differentia in the Aristotelian tradition

The paper distinguishes different bodies of logical theory in Aristotle's writings on genus and differentia. It outlines some significant innovations introduced to the theory by Abelard and Avicenna. It sketches a family of intensional logics intended as formal representations of the various historical theories considered. This family is centred on a core theory that is neutral with respect to the differences between those historical theories, while the remaining members of the family give formal expression to the characteristic postulates and definitions adopted in specific historical theories. A research program is adumbrated for extending the paper's approach to other historical material.