The human mind, he tells us, has two kinds of intelligence--the passive intelligence (νοῦς παθητικός), which is the receptacle of forms (δεκτικὸν τοῦ εὶδους); and the active intelligence (νοῦς ποιητικός), which impresses the seal of thought upon the data furnished by experience, and combines them into the unity of a single judgment, thus attaining "general notions." [688] The passive intelligence (the "external perception" of modern psychology) perceives the individual forms which appear in the external world, and the active intelligence (the intellect proper) classifies and generalizes according to fixed laws or principles inherent in itself; but of these fixed laws--πρῶτα νοήµατα--first thoughts, or à priori ideas, he offers no proper account; they are, at most, purely subjective. This, it would seem, was, in effect, a return to the doctrine of Protagoras and his school, "that man--the individual--is the measure of all things." The aspects under which objects present themselves in consciousness, constitute our only ground of knowledge; we have no direct, intuitive knowledge of Being in se. The noetic faculty is simply a regulative faculty; it furnishes the laws under which we compare and judge, but it does not supply any original elements of knowledge. Individual things are the only real entities, [689] and "universals" have no separate existence apart from individuals in which they inhere as attributes or properties. They are consequently pure mental conceptions, which are fixed and recalled by general names. He thus substitutes a species of conceptual-nominalism in place of the realism of Plato. It is true that "real being" (τὸ ὄν) is with Aristotle a subject of metaphysical inquiry, but the proper, if not the only subsistence, or οὐαία, is the form or abstract nature of things. "The essence or very nature of a thing is inherent in the form and energy" [690] The science of Metaphysics is strictly conversant about these abstract intellectual forms just as Natural Philosophy is conversant about external objects, of which the senses give us information. Our knowledge of these intellectual forms is, however, founded upon "beliefs" rather than upon immediate intuition, and the objective certainty of science, upon the subjective necessity of believing, and not upon direct apperception.
[Footnote 688: ][ (return) ] "On the Soul," ch. vi.; "Ethics," bk. vi. ch. i.
[Footnote 689: ][ (return) ] "Metaphysics," bk. vi. ch. xiii.
[Footnote 690: ][ (return) ] Ibid., bk. vii. ch. iii.
The points of contrast between the two methods may now be presented in a few sentences. Plato held that all our cognitions are reducible to two elements--one derived from sense, the other from pure reason; one element particular, contingent, and relative, the other universal, necessary, and absolute. By an act of immediate abstraction Plato will eliminate the particular, contingent, and relative phenomena, and disengage the universal, necessary, and absolute ideas which underlie and determine all phenomena. These ideas are the thoughts of the Divine Mind, according to which all particular and individual existences are generated, and, as divine thoughts, they are real and permanent existences. Thus by a process of immediate abstraction, he will rise from particular and contingent phenomena to universal and necessary principles, and from these to the First Principle of all principles, the First Cause of all causes--that is, to God.
Aristotle, on the contrary, held that all of our knowledge begins with "the singular," that is, with the particular and the relative, and is derived from sensation and experience. The "sensible object," taken as it is without any sifting and probing, is the basis of science, and reason is simply the architect constructing science according to certain "forms" or laws inherent in mind. The object, then, of metaphysical science is to investigate those "universal notions" under which the mind conceives of and represents to itself external objects, and speculates concerning them. Aristotle, therefore, agrees with Plato in teaching "that science can only be a science of universals," [691] and "that sensation alone can not furnish us with scientific knowledge." [692] How, then, does he propose to attain the knowledge of universal principles? How will he perform that feat which he calls "passing from the known to the unknown?" The answer is, by comparative abstraction. The universal being constituted by a relation of the object to the thinking subject, that is, by a property recognized by the intelligence alone, in virtue of which it can be retained as an object of thought, and compared with other objects, he proposes to compare, analyze, define, and classify the primary cognitions, and thus evoke into energy, and clearly present those principles or forms of the intelligence which he denominate "universals." As yet, however, he has only attained to "general notions," which are purely subjective, that is, to logical definitions, and these logical definitions are subsequently elevated to the dignity of "universal principles and causes" by a species of philosophic legerdemain. Philosophy is thus stripped of its metaphysical character, and assumes a strictly logical aspect. The key of the Aristotelian method is therefore the
[Footnote 691: ][ (return) ] "Ethics," bk. vi. ch. vi.
[Footnote 692: ][ (return) ] "Post. Analytic," bk. i. ch. xxxi.
ARISTOTELIAN LOGIC.