At Euthydemus 278–282, Socrates produces an argument that has almost universally been agreed to entail that wisdom is sufficient for happiness, necessary for happiness, or both. According to these standard readings, this is because Socrates ties wisdom to correct use of one's assets. Since wisdom is necessary or sufficient for correct use and correct use is necessary or sufficient for happiness, wisdom bears the same relation(s) to happiness, mutatis mutandis. I propose a split-level reading of this passage. On the level (...) of natures, Socrates aims to establish that a causal-explanatory relation holds between the nature of wisdom and correctness such that wisdom by nature always produces correctness; ignorance, conversely, by nature never produces correctness. However, on the level of individuals, the causal relations are defeasible such that the wise sometimes fail and the ignorant sometimes succeed. Thus this reading does not entail that having wisdom is necessary or sufficient for correct use or for happiness. If this split-level reading is correct, then this passage, the locus classicus for the necessity and sufficiency theses, fails to establish either. (shrink)