Scientia demonstrativa in the Middle Ages

From the thirteenth century down to the Renaissance, philosophers attempted to forge plausible accounts of Aristotelian ‘demonstrative science’ and its basis, the ‘knowledge-producing syllogism’ (syllogismus faciens scire). The term ‘scientia demonstrativa’ is ambiguous, referring both to the knowledge a demonstrative syllogism effects in someone who understands it and to a system of syllogisms comprising propositions which satisfy the requirements for demonstration stipulated in Aristotle's Posterior Analytics. In expounding Aristotle's theory, medieval authors typically interpret and criticise it in the light of their own conceptions and doctrines; for example, their treatments of the requirements that premisses of demonstrative syllogisms be true, necessary, and certain invoke various views of truth, necessity, and certainty. So while it is true that almost all the major figures of medieval philosophy in some sense endorse what is traditionally called ‘the Aristotelian ideal of demonstrative science’, this appearance of unanimity can be misleading. The generalisation that this ideal dominated medieval thinking regarding scientific knowledge obscures or ignores the variety in philosophical accounts of its foundation and scope.

Much of our current understanding of medieval epistemology is based on doctrines concerning acquaintance with and knowledge of particular entities or states of affairs, and the subsequent formation of general concepts. Because discussions of more elaborate cognitive activities, those involving relatively complex judgements and inferences, have until recently received less attention, the full significance of theories of demonstrative science in late medieval epistemology remains to be determined.