I.
Iamblichus, defended Aristotle’s Categories, [563].
[Ideas], Platonic Theory of, not required for Demonstration, [221]; as set forth by Plato himself, [553]; psychological ground for, [554]; objections urged against, in Sophistes and Parmenides, [556] seq.; objections urged by Aristotle against, [558]; allusions to in books of the Metaphysica, [595], [598], [600], [603], [606], [607], [612], [617], [619], [620].
Idem, three senses of, [277], [350]; a topic in First Philosophy, [584].
Identity, Maxim of, among the præcognita of Demonstration, [212].
Idomeneus, letter to, from Epikurus, [654].
Ignoratio Elenchi, Fallacy of, [387]; all fallacies may be brought to, [390]; how to solve, [412].
Immortality, not of the individual, [462], [489], [490].
Immoveable, essence, subject of Ontology, also of Mathematics, [423], [593], [619]; Prime Movent, [624].
Impossibile, Reductio ad, see [Reductio].
Impossible, The, senses of, [638]; differs from the False, [638].
Induction, sole proof of the rules for converting propositions, [146], [147]; everything believed through Syllogism or upon, [187], [194], [226]; the Syllogism from or out of, [187] seq.; the opposite of genuine Syllogism, [190]; plainer and clearer to us, than Syllogism, [191]; Aristotle’s attempt to reduce, to syllogistic form, [192], [193]; wanting in the first requisite of Syllogism — necessity of sequence, [193], [197]; presupposed in Syllogism, [194]; the antithesis of, to Syllogism, obscured by Aristotle’s treatment, [198], [199]; as part of the whole process of Scientific Inference, [199], [201]; true character of, apprehended by Aristotle, but not followed out, [199], [200]; Logic of, neglected by the expositors after Aristotle till modern times, [200]; requisites to a Logic of, [201]; supplies the premisses of Demonstration, starting from particulars of sense, [226], [258], [259], [562], [576]; repeated and uncontradicted, gives maximum of certainty, [260]; process of, culminates in the infallible Noûs, [259]-61; procedure by way of, in Dialectic, [358]; most suitable to a young beginner in Dialectic, [374].
Inductive School, exact question between the, and Sir W. Hamilton, [567].
Infinite, the, exists only potentially, not actually except in a certain way for our cognition, [615]; no body is, [632] seq.
Intellect, see [Noûs].
Intellectus Agens, relation of, to the Patiens, [488], [489]; eternal and immortal, but not in the individual, [488], [489].
Intellectus Patiens, relation to the Agens, [488], [489]; belongs to and perishes with the individual, [488], [489].
Interpretatione, Treatise de, not named, but its contents presupposed, in Analytica and Topica, [56]; subject of, how related to subject of Categoriæ, [57], [59], [108], [109]; last section of, out of connection, [134]; contains first positive theory of Proposition, [136]; summary of, [139].
Interrogation in Dialectic and in Science, [222].
Irregularity, principle of, in the Kosmos, see [Chance].
Isokrates, corresponded with Nikokles, [7], [23]; his rhetorical school, [21]; his style of composition and teaching, [22]; attacked by Aristotle, [24]; defended by Kephisodorus, [24].