Aspasius, the earliest commentator in the Aristotelian school whose commentary has survived as more than excerpts, asks if the most generic emotions are just pleasure and pain, or the four given by the Stoics (and often listed by Plato ), who add fear and appetite, or the six sometimes listed by Plato . Aspasius backs the pleasure-pain pair, ignoring Aristotle ’s Rhetoric, Book 2, of which he shows little knowledge [...], where Aristotle defines a number of emotions in terms of different types of desire, and does not treat pleasure as a genus, even though pleasure and distress feature as accompaniments.
The pleasure-pain pair are hard to defend for a number of reasons. Some emotions seem to involve both, so do not fall neatly under either as genus. Again, the Stoics would complain that Aspasius leaves out the two emotions (appetite and fear) involving thoughts about action. But Aspasius makes a telling point against their view of anger as an appetite involving thoughts about revenge. Angry parents need not think about revenge on their children at all.
Whereas Aristotle ’s Rhetoric is indifferent whether the thoughts involved in emotion constitute appearance (phantasia) or belief (doxa), the Stoics insist on belief or judgement (krisis), which for them is a voluntary giving of assent (sunkatathesis) to appearances. The earlier Aristotelian Andronicus had Stoicised, defining emotion as involving belief or judgement, or rather supposition (hupolep-sis), which for Aristotle (DA 3.3, 427b25), is the genus of belief, the supposition that things are good or bad. Aspasius retorts that when we are amused by a witty speech, we need not suppose that there is anything good at hand; we are merely moved by the pleasant.
There are other references to Stoicism in Aspasius’ account. He speaks of the contractions (sunkhuseis) and diffusions (diakhuseis) felt in the chest in distress and pleasure, which the Stoics took to be contractions and expansions of the physical soul. He also speaks of the attachment (oikeiosis), which the Stoics highlighted in the context of family love and self-love as providing a natural basis for the extension of justice to all humans.
Aspasius refers among Aristotelian predecessors not only to Andronicus, but also to Boethus, but rather confusingly truncates Boethus’ definition of emotion. This may have been: a motion of the irrational or emotional (pathetikon) part of the soul, which is also a detected change of quality in the body, and which is above a certain magnitude. Aspasius criticises him for apparently thinking that a detected soul motion, if too small, would not be an effect in the body.