This is the origin of knowledge, psychologically regarded (in the De Anima). Logically regarded, the origin of all teaching and learning of an intellectual kind is a process of induction (ἐπαγωγή) from particulars to universal, and of syllogism (συλλογισμός) from universal to further particulars; induction, whenever it starts from sense, becomes the origin of scientific knowledge (ἐπιστήμη); while there is also a third process of example (παράδειγμα) from particular to particular, which produces only persuasion. In acquiring scientific knowledge, syllogism cannot start from universals without induction, nor induction acquire universals without sense. At the same time, there are three species of syllogism, scientific, dialectical and eristical or sophistical; and in consequence there are different ways of acquiring premisses. In order to acquire the knowledge of the true and primary principles of scientific knowledge, and especially the intelligence of the universal essence of the subject, which is always true, the process of knowledge consists of (1) sense (αἴσθησις), which receives the essence as individual, (2) memory (μνήμη), which is a retention of sensible impression, (3) experience (ἐμπειρία), which consists of a number of similar memories, (4) induction (ἐπαγωγή), which infers the universal as a fact (τὸ ὅτι), (5) intellect (νοῦς), which apprehends the principle (ἀρχή); because it is a true apprehension that the universal induced is the very essence and formal cause of the subject: thereupon, scientific syllogism (ἐπιστημονικὸς συλλογισμός), making the definition (ὁρισμος) of this essence the middle term (τὸ μέσον), becomes a demonstration (ὁρισμος) of the consequences which follow from the essence in the conclusion. Such then is science. In order to acquire the probabilities (τὰ ἔνδοξα) of opinion (δόξα), which are the premisses of dialectical syllogism, the process is still induction, as in science, but dialectical induction by interrogation from the opinions of the answerers until the universal is conceded: thereupon the dialectical syllogism (διαλεκτικὸς συλλογισμός) deduces consequent opinions in the conclusion. Nor does the process of acquiring the premisses of eristical syllogism, which is fallacious either in its premisses or in its process, differ, except that, when the premisses are fallacious, the dialectical interrogations must be such as to cause this fallacy. Hence, as science and dialectic are different, so scientific induction and syllogism must be distinguished from dialectical induction and syllogism. Dialectic is useful, for exercise, for conversation and for philosophical sciences, where by being critical it has a road to principles. But it is by a different process of sense, memory, experience, induction, intelligence, syllogism, that science becomes knowledge of real causes, of real effects, and especially of real essences from which follow real consequences, not beyond, but belonging to real substances. So can we men, not, as Plato thought, by having in our souls universal principles innate but forgotten, but by acquiring universal principles from sense, which is the origin of knowledge, arrive at judgments which are true, and true because they agree with the things which we know by sense, by inference and by science. Such is Aristotle’s psychological and logical realism, contained in the De Anima and logical treatises.
2. Practice (πρᾶξις).—In this natural world of real substances, human good is not an imitation of a supernatural universal form of the good, but is human happiness; and this good is the same both of the individual as a part and of the state as a whole. Ethics then is a kind of Politics. But in Ethics a man’s individual good is his own happiness; and his happiness is no mere state, but an activity of soul according to virtue in a mature life, requiring as conditions moderate bodily and external goods of fortune; his virtue is (1) moral virtue, which is acquired by habituation, and is a purposive habit of performing actions in the mean determined by right reason or prudence; requiring him, not to exclude, but to moderate his desires; and (2) intellectual virtue, which is either prudence of practical, or wisdom of speculative intellect; and his happiness is a kind of ascending scale of virtuous activities, in which moral virtue is limited by prudence, and prudence by wisdom; so that the speculative life of wisdom is the happiest and most divine, and the practical life of prudence and moral virtue secondary and human. Good fortune in moderation is also required as a condition of his happiness. Must we then, on account of misfortunes, look with Solon at the end, and call no man happy till he is dead? Or is this altogether absurd for us who say that happiness is an activity? Virtuous activities determine happiness, and a virtuous man is happy in this life, in spite of misfortunes unless they be too great; while after death he will not feel the misfortunes of the living so much as to change his happiness. Still, for perfect happiness a man should prefer the speculative life of divine intellect, and immortalize (ἀθανατίζειν) as far as possible. For intellect is what mainly makes a man what he is, and is divine and immortal.
To turn from Ethics to Politics, the good of the individual on a small scale becomes on a large scale the good of the citizen and the state, whose end should be no far-off form of good, and no mere guarantee of rights, but the happiness of virtuous action, the life according to virtue, which is the general good of the citizen. Hence, the citizen of the best state is he who has the power and the purpose to be governed and govern for the sake of the life according to virtue.
A right government is one which aims at the general good, whereas any government which aims at its own good is a deviation. Hence governments are to be arranged from best to worst in the following order:—
I. Right governments (ὀρθαὶ πολιτείαι), aiming at the general good:—
i. Monarchy, of one excelling in virtue:
ii. Aristocracy, of a class excelling in virtue:
iii. Commonwealth, of the majority excelling in virtue.
II. Deviations (παρεκβάσεις), aiming at the good of the government:—
i. Democracy, aiming at the good of the majority: