Abstract

Hankinson discusses Ptolemy, whose geometrical model was the most sophisticated development in ancient astronomy, at the beginning of this chapter; but the main focus is on Galen's comprehensive account of causation. Galen insists that antecedent conditions are causes, because the effects are conditioned by them; furthermore, physical dispositions are also preceding causes, and together with the external antecedent conditions they produce the immediate necessary and sufficient containing causes of diseases. Galen combines Aristotle's four causes, except the formal cause, with the instrumental cause of Middle Platonism; he also distinguishes incidental and essential causes. From the Platonic tradition, Galen adopts a directed teleology, and an artisan‐god that is constrained by material necessity. Galen also contributes to the debate on freedom and responsibility: he argues that we remain responsible for what we do even if our actions are determined by causes outside our control.