In this thesis, I revisit the question of Aristotelian influences on Plotinus’ thought, but mediated by Alexander of Aphrodisias. This methodological choice was guided by Porphyry’s comments in the Life of Plotinus, to the effect that Aristotle’s Metaphysics is condensed in Plotinus’ writings, and that Plotinus studied Alexander’s commentaries. I proceed on the understanding that Plotinus was influenced not simply by Aristotle, but by Aristotle as interpreted by Alexander.
I focus on two interrelated areas. The first is the role of dialectic in philosophy. I argue that according to Alexander, dialectic is the primary part of philosophic practice and thus used throughout Aristotle’s writings. Demonstration proceeds by deduction from first principles. But first principles are approached by way of aporiai and dialectic. Dialectic is the way up to first principles, the way of discovery, only after which can one have properly demonstrable knowledge.
For the Aristotelians, dialectic is guided and structured by the principle of non-contradiction. For Plotinus, too, dialectic is central to philosophy. But he rejects the Peripatetic claim that dialectic is ultimately guided by the PNC. For Plotinus, the Aristotelian treatment of dialectic is consequent upon a failure to fully understand the highest metaphysical principles. Plotinus argues that the PNC must be abandoned if one is to have contemplative knowledge of the first causes, since the highest principles transcend the PNC, resulting in a substantially different conception of dialectic. The first principle of thought and being are unified by Plotinus in the divine Intellect.
The second subject discussed is the nature and causal role of the divine Intellect. Alexander famously took the productive intellect from De anima to be identical with the divine intellect of the Metaphysics. He attempts to explain the actualization of the human intellect by reference to the divine intellect but struggles to explain this causal role. I argue that Plotinus responds to the Peripatetic account of the divine Intellect, answering the problems raised by Alexander’s interpretative approach. The Peripatetics failed to understand that the divine Intellect is neither the simplest nor the highest principle, and that the intelligibles must be in the divine Intellect.