One of the four cardinal Stoic TERMπάθη. In the matrix of passions (good/evil × present/future), ἡδονή occupies the slot apparent good in the present: the soul judges "what I am experiencing now is a good for me" — and from this false assent arises an "irrational expansion" (ἄλογος ἔπαρσις) of the soul. Chrysippus' formula: ἡδονή ἐστιν ἄλογος ἔπαρσις. This pneumatic physicalisation of emotion is typical of the Stoics — a passion is a concrete movement of the pneuma in the ruling part (an expansion or a contraction).

The Stoic position differs from, and stands in contrast to, the Epicurean: for Epicurus, ἡδονή is the telos, the final end that defines a successful life; for the Stoics, ἡδονή is a pathological state of false assent, the opposite of the smooth flow of life. The Stoics are not, however, ascetics: they distinguish ἡδονή (the passion) from χαρά — its eupatheia-correlate, the sage's "rational joy" at the genuine good, namely virtue. χαρά occasions no irrational expansion and is in concord with reason.

Species of ἡδονή: θέλξις (enchantment), ἀσμενισμός (self-satisfaction), ἐπιχαιρεκακία (malicious joy, Schadenfreude), τέρψις (sensuous delight), and so on.

SVF III 391–442; specifically on ἡδονή: III 414, 416, 421; DL VII 114–115; Stob. Ecl. II 90, 95 W; Cic. Tusc. IV 11–14, 19–20; LS 65. The Epicurean parallel: Epic. Ep. Men. 128–132. In Marcus: Med. 2.10; 5.26; 6.51; 7.55; 8.10; 9.7.

In 02-10 ἡδονή is the state under whose sway the agent acts in offences born of TERMdesire: «ὑφ' ἡδονῆς ἡττώμενος» — "overcome by pleasure." This is the double argument of Theophrastus: (a) the offence itself is motivated by the pursuit of pleasure; (b) it is committed with pleasure. The comparison with TERMλύπη (with which the angry person commits his offence) yields a criterion: an offence committed "with pleasure" is worse than one committed "with grief," because pleasure marks inner assent to the bad, while grief marks resistance. This is a precise diagnostic inversion: the emotional background of an offence marks the degree of voluntariness.