Abstract
The article deals with the oldest criticism of Anaximander’s monism, for which we have evidence, found in John Philoponus’ commentary on the first book of Aristotle’s Physics . Philoponus’ argumentation is analytically examined and explained, its premises brought to light and its conclusions evaluated. It is shown how his inquiry, although anticipating modern discussions about the classification of Anaximander’s doctrine in terms of ‘monism’ and ‘pluralism’, differs from the contemporary approach to the problem when it comes to both results and methodology