Monism and Difference: Syrianus, Aristotle and the Sophist

In Metaphysics N 2, Aristotle criticizes Plato and the Academics for setting up the problem of principles “in an obsolete way”. For they thought all things would be one (viz. Being itself) if they did not demonstrate, against Parmenides, that not-being is. And this assumption, for Aristotle, betrays a more fundamental and questionable Eleatic debt in their ontology, namely their commitment to the obsolete view that being, taken in its own right, is one. By contrast, Aristotle believes being is originally multiple and said in many ways, so there is no need to demonstrate that not-being is, to justify as much. In his commentary on Book N, Syrianus replies to Aristotle and argues, among other things, both that his criticisms are flawed and that his own ontology can only stand if the Platonist account of multiplicity, difference and not-being is also endorsed. I scrutinize these counterobjections and argue that this debate reflects two essentially different ways of explaining fundamental facts in the structure of reality.