Abstract
The purpose of this article is to offer analysis of the passage on evil in the Theaetetus 176a4-8. I submit that it stands in anticipatory relation to Plato’s mature theory of evil, as it can be deduced from the Timaeus. My assumption is that in the Theaetetus passage two contrary principles are postulated, one of which is the cause of good, while the other is the cause of evil. In order to support that assumption, I shall argue that a) Plato’s doctrine of the Forms is present in the Theaetetus Digression; b) the word ‘good’ at 176a6 refers to Plato’s highest entity – αὐτὸ ἀγαθόν; c) τὰ κακά of 176a5 are not to be identified with the opposite of τὸ ἀγαθόν mentioned in the same line; d) the ὑπεναντίον of 176a6, the subordinated opposite of τὸ ἀγαθόν, and the second ἀνάγκη in the passage could denote the same entity, i.e. the Timaean Necessity.