Aristotle classifies the phenomena of the soul (the non-rational soul) into three — Passions — Capacities or Faculties — States. The first are the occasional affections — anger, fear, envy, joy, aversion — “in short, everything that is accompanied by pleasure or painâ€� (ii. 5). The second are, the capacities of being moved by such affections — the affective faculties, if one may so call them (ib. So Eth. Eudem. ii. 2). The third are, those habits according to which we are said to be well or ill disposed towards this or that particular affection: to be disposed to violent anger or violent fear, is a bad habit. Virtues and vices are neither affections, nor faculties, but habits, either good or bad. This is the genus to which the virtues belong (τῷ γένει — Eth. Nic. ii. 5). Virtue is that habit from the possession of which a man is called good, and by which he performs well his appropriate function (ii. 6). It consists in a certain medium between two extremes, the one of excess, the other of defect — a medium not positive and absolute, but variable and having reference to each particular person and each particular case — neither exceeding nor falling short of what is proper (ii. 6). All ethical virtue aims at the attainment of this middle point in respect to our affections and actions — to exhibit each on the proper occasions, in the proper degree, towards the proper persons, &c. This middle point is but one, but errors on both sides of it are numberless: it must be determined by reason and by the judgment of the prudent man (ii. 6).
Virtue therefore, according to its essence and generic definition (κατὰ μὲν τὴν οὐσίαν, καὶ τὸν λόγον τὸν τί ἠν εἶναι λέγοντα), is a certain mediocrity.
But there are some actions and some affections which do not admit of mediocrity, and which imply at once in their names evil and culpability (ii. 6) — such as impudence, envy, theft, &c. Each of these names implies in its meaning a certain excess and defect, and does not admit of mediocrity: just as temperance and courage imply in their meaning the idea of mediocrity, and exclude both excess and defect.
Aristotle then proceeds to apply his general doctrine — that virtue or excellence consists in a medium between two extremes, both defects — to various different virtues. He again insists upon the extreme difficulty of determining where this requisite medium is, in each individual instance: either excess or defect is the easy and natural course. In finding and adhering to the middle point consists the well, the rare, the praiseworthy, the honourable (ii. 9). The extremes, though both wrong, are not always equally wrong: that which is the most wrong ought at any rate to be avoided: and we ought to be specially on our guard against the seductions of pleasure (ib.), since our natural inclinations carry us in that direction.
Aristotle so often speaks of the propriety of following nature, and produces nature so constantly as an authority and an arbiter, that it seems surprising to find him saying — “We must be on our guard with reference to the things whereto we ourselves are prone. For some of us are by nature disposed towards some things, others towards others.� — “But we must drag ourselves away in the opposite direction� (ii. 9).
There is a singular passage in the same chapter with respect to our moral judgments. After having forcibly insisted on the extreme difficulty of hitting the proper medium point of virtue, he says that a man who commits only small errors on one side or on the other side of this point, is not censured, but only he who greatly deviates from it — he then proceeds — “But it is not easy to define in general language at what point a man becomes deserving of censure: nor indeed is it easy to do this with regard to any other matter of perception. Questions of this sort depend upon the circumstances of the particular case, and the judgment upon each resides in our perception� (ii. 9).
The first five chapters, of the third Book of the Ethics, are devoted to an examination of various notions involved in our ideas of virtue and vice — Voluntary and Involuntary — ἑκούσιον καὶ ἀκούσιον — Ignorance — ἄγνοια — Choice or resolution, consequent upon previous deliberation — προαίρεσις.
Those actions are involuntary, which are done either by compulsion, or through ignorance. An action is done by compulsion when the proximate cause of it (or beginning — ἀρχὴ) is something foreign to the will of the agent — the agent himself neither concurring nor contributing. Actions done from the fear of greater evils are of a mixed character, as where a navigator in a storm throws his goods overboard to preserve the ship. Such actions as this, taken as a class, and apart from particular circumstances, are what no one would do voluntarily: but in the particular circumstances of the supposed case, the action is done voluntarily. Every action is voluntary, wherein the beginning of organic motion is, the will of the agent (iii. 1).
Men are praised if under such painful circumstances they make a right choice — if they voluntarily undergo what is painful or dishonourable for the purpose of accomplishing some great and glorious result (ib.): they are censured, if they shrink from this course, or if they submit to the evil without some sufficient end. If a man is induced to do what is unbecoming by the threat of evils surpassing human endurance, he is spoken of with forbearance: though there are some crimes of such magnitude as cannot be excused even by the greatest possible apprehension of evil, such as death and torture. In such trying circumstances, it is difficult to make a right choice, and still more difficult to adhere to the choice when it is made.
What is done through ignorance, can never be said to be done voluntarily: if the agent shall be afterwards grieved and repentant for what he has done, it is involuntary. If he be not repentant, though he cannot be said to have done the deed voluntarily, yet neither ought it to be called involuntary.