In this paper I explore the ways in which Alexander of Aphrodisias employs and develops so-called ‘common notions’ as reliable starting points of deductive arguments. He combines contemporary developments in the Stoic and Epicurean use of common notions with Aristotelian dialectic, and axioms. This more comprehensive concept of common notions can be extracted from Alexander’s commentary on Metaphysics A 1–2. Alexander puts Aristotle’s claim that ‘all human beings by nature desire to know’ in a larger deductive framework, and adds weight to Aristotle’s use of the common understanding of the notion of ‘wisdom’. Finally I will indicate how these upgraded common notions are meant to play an important role in the general framework of metaphysics as a science.
One of Kant’s categories—a priori concepts the possession and applicability of which are necessary conditions of possible experience—is a concept of necessity. But it is unclear why the concept of necessity, as Kant defines it, should be a category thus understood. My aim is to offer a reading of Kant that fills this lacuna: the category of necessity is required to make necessity as it features in the world of experience understandable: a concept that the understanding can grasp and employ in cognition of objects. Kant’s view has potential wider significance for accounts of the function of necessity judgments.
This paper draws out and connects two neglected issues in Kant’s conception of a priori knowledge. Both concern topics that have been central to contemporary epistemology and to formal epistemology in particular: knowability and luminosity. Does Kant commit to some form of knowability principle according to which certain necessary truths are in principle knowable to beings like us? Does Kant commit to some form of luminosity principle according to which, if a subject knows a priori, then they can know that they know a priori? I defend affirmative answers to both of these questions, and by considering the special kind of modality involved in Kant’s conceptions of possible experience and the essential completability of metaphysics, I argue that his combination of knowability and luminosity principles leads Kant into difficulty.