Hitman Knowledge [cf. (3), above]. — (a) The Pla- tonic Dinlectjc. — From the beginnings of Greek philos- ophy reflection lias revealed a twofold element in the contents of the knowing human mind: an abstract, permanent, immutable element, usually referred to the intellect or reason ; and a concrete, changeable, ever-shifting ::lenient, usually referred to the imagina- tion and the external senses. Now, can the real world possess such opposite characteristics? Or, if not, which set really represents it? For Heraclitus and the earlier lonians, stability is a delusion; all reality is change — ird^ra peT. For Parmenides and the Eleatics, change is delusion; reality is one, fixed, and stable. But then, whence the delusion, if such there be, in either alternative? Why does our knowledge speak with such uncertain voice, or which alternative are we to believe? Both, answers Plato, but intellect more than spn.se. What realities, the latter asks, are revealed by those abstract, universal notions we pos- sess — of being, number, cause, goodness, etc., by the necessary, immutable truths we apprehend and the comparison of those notions? The dialectic of the Platonic "Ideas" is anoble, if unsuccessful, attempt to answer this question. These notions and truths, says Plato, have for objects ideas which constitute the real world, the tnundus intclligibilis, of which we have thus a direct and immediate mtellectual intuition. These beings, which are objects of our intellectual knowledge, these ideas, really exist in the manner in which they are represented by the intellect, i. e. as necessary, universal, inunutable, eternal, etc. B\it where is this mumltis intdligibilis.' It is a world apart (xwp's), separate from the world of fleeting phenom- ena revealed to the senses. And is this latter world, then, real or unreal? It is, says Plato, but a shadowy reflex of reality, a dissolving-view of the ideas, about which our conscious sense-imprc.ssions can give us mere opinion (56fa), but not that reliable, proper knowledge (^ttiitt-^M')) which we have of the ideas. This is imsatisfactorj'. It is an attempt to explaui an admitted connexion between the noumenal and the phenomenal elements in knowledge by suppressing the reality of the latter altogether. Nor is Plato any more succes.sfid in his I'lideavour to show how the idea, which for him is a really existing being, can be at the same time one and manifold, or, in other words, how it can be universal, like the mental notion that re- presents it.
(b) Aristotelean and Scholastic Dialectic. — Aristotle taught, in opposition to his master Plato, that these "ideas" or objects of our intellectual notions do not exist apart from, but arc embodied in, the concrete, individual data of sense. It is one and the same reality that reveals itself under an abstract, universal, static aspect to the intellect, and under a concrete, manifoW, dynamic aspect to the senses. The C'hris- tian philosophers of the Middle .\ges took up and de- veloped this Aristotelean conception, making it one of the cardinal doctrines of .Scholastic philosophy, the doctrine of modem Realism. The object of the ab- stract, universal notion, they taught, is real being; it constitutes and is identical with the individual data of sense-knowledge ; it is numerically multiplied and individualized in them, while it is unified as a class- concept or universal notion (unum commune plurihus) by the abstractive power of the intellect which appre- hends the element conunon to the individuals of a class without their difTerentiating characteristics. The universal notion thus exists as universal only in the intellect, but it has a foundation in the individual data of sense, inasmuch as the content of the notion really exists in these sense-data, though the mode of its existence there is other than the mode in which the notion exists in the intellect: universale est jor- miililer in mente, jumldmcntalitrr in re. Nor does the intellect, in thus representing individual phenomena by universal notions, falsify its object or render intel-
lectual knowledge unreliable; it represents the Real in.adequately, no doubt, not exhaustively or compre- hensively, yet faithfully so far as it goes; it does not misrepresent reality, for it merely asserts of the latter the content of its universal notion, not the mode (or universality) of the latter, as Plato did.
But if we get all our universal notions, necessary judgments, and intuitions of immutable truth through the ever-changing, individual data of sense, how are we to account for the timeless, spaceless, changeless, necessary character of the relations we establish be- tween these objects of abstract, intellectual thought: relations such as "Two and two are four", "Whatever happens has a cause", " Vice is blameworthy "7 Not because our own or our ancestors' perceptive faculties have been so accustomed to associate certain elements of consciousness that wo are unable to dissociate them (as materialist and evolutionist philosophers would say); nor yet, on the other hand, because in appre- hending these necessary relations we have a direct and immediate intuition of the necessary, self-existent, Divine Being (as the Ontologists have said, and as some interpret Plato to have meant); but simply be- cause we are endowed with an intellectual faculty which can apprehend the data of sense in a static con- dition and establish relations between them abstract- ing from all change.
By means of such necessary, self-evident truths, applied to the data of sense-knowledge, we can infer that our own minds are beings of a higher (spiritual) order than material things and that the beings of the whole visible universe — ourselves included — are con- tingent, i. e. essentially and entirely dependent on a necessary, all-perfect Being, who created and con- serves them in existence. In opposition to this crea- tionist philosophy of Theism, which arrives at an ulti- mate plurality of being, may be set down all forms of Monism or Pantheism, the philosophy which termin- ates in the denial of any real distinction between mind and matter, thought and thing, subject and object of knowledge, and the assertion of the ultimate unity of being.
(c) The Kantian Dialectic. — W'hile Scholastic philos- ophers understand by reality that which is the object directly revealed to, and apprehended by, the knowing mind through certain modifications wrought by the reality in the sensory and intellectual faculties, ideal- i.st or phenomenalist philosophers a.ssvnne that the direct object of our knowledge is the mental state or modification itself, the mental appearance, or phenom- enon, as they call it; and because wo cannot clearly understand how the knowing mind can transcend its own revealed, or phenomenal, self or states in the act of cognition, so as to apprehenfl something other than the immediate, empirical, subjective content of that act, these philosophers are inclined to doubt the val- idity of the "inferential leap" to reality, and conse- quently to maintain that the speculative reason is unable" to reach beyond subjective, mental appear- ances to a knowledge of things-in-themselves. Thus, according to Ivant, our necessary and universal judg- ments about sense-data derive their necessity and universality from certain innate, subjective equip- ments of the mind called categories, or forms of thought, and are therefore validly applicable only to the phenomena or states of sense-consciousness. We are, no doubt, compelled to think of an unperceived real world, underlying the phenomena of external sensation, of an unperceived real ajo, or mind, or soul, underlying the conscious flow of phenomena which constitute the empirical or phenomenal egn, and of an absolute and ultimate underlying, unconditioned Cause of the ego and the world alike; but these three ideas of the reason — the soul, the world, and God — are mere natural, necessary products of the mental process of thinking, mere regulative principles of thought, devoid of all real content, and therefore in-