You allow that this difference corresponds to the difference of _knowledge_ and _opinion_; and the _opinionable_ is to the _knowable_ as the _image_ to the _reality_.[531]
[Footnote 530: As in the simile of the cave ("Republic," bk. vii. ch. i.
and ii.).]
[Footnote 531: The a.n.a.logy between the "images produced by reflections in water and on polished surfaces" and "the images of external objects produced in the mind by sensation" is more fully presented in the "Timaeus," ch. 19.
The eye is a light-bearer, "made of that part of elemental fire which does not burn, but sheds a mild light, like the light of day.... When the light of the day meets the light which beams from the eye, then light meets like, and make a h.o.m.ogeneous body; the external light meeting the internal light, in the direction in which the eye looks. And by this h.o.m.ogeneity like feels like; and if this beam touches any object, or any object touches it, it transmits the motions through the body to the soul, and produces that sensation which we call _seeing_....
And if (in sleep) some of the strong motions remain in some part of the frame, they produce within us likenesses of external objects,... and thus give rise to dreams.... As to the images produced by mirrors and by smooth surfaces, they are now easily explained, for all such phenomena result from the mutual affinity of the external and internal fires. The light that proceeds from the face (as an object of vision), and the light that proceeds from the eye, become one continuous ray on the smooth surface."]
Now we have to divide the segment which represents intelligible things in this way: The one part represents the knowledge which the mind gets by using things as images--the other; that which it has by dealing with the ideas themselves; the one part that which it gets by reasoning downward from principles--the other, the principles themselves; the one part, truth which depends on hypotheses--the other, unhypothetical or absolute truth.
Thus, to explain a problem in geometry, the geometers make certain hypotheses (namely, definitions and postulates) about numbers and angles, and the like, and reason from them--giving no reason for their a.s.sumptions, but taking them as evident to all; and, reasoning from them, they prove the propositions which they have in view. And in such reasonings, they use visible figures or diagrams--to reason about a square, for instance, with its diagonals; but these reasonings are not really about these visible figures, but about the mental figures, and which they conceive in thought.
The diagrams which they draw, being visible, are the images of thoughts which the geometer has in his mind, and these images he uses in his reasoning. There may be images of these images--shadows and reflections in water, as of other visible things; but still these diagrams are only images of conceptions.
This, then, is _one_ kind of intelligible things: _conceptions_--for instance, geometrical conceptions of figures. But in dealing with these the mind depends upon a.s.sumptions, and does not ascend to first principles. It does not ascend above these a.s.sumptions, but uses images borrowed from a lower region (the visible world), these images being chosen so as to be as distinct as may be.
Now the _other_ kind of intelligible things is this: that which the _Reason_ includes, in virtue of its power of reasoning, when it regards the a.s.sumptions of the sciences as (what they are) a.s.sumptions only, and uses them as occasions and starting-points, that from these it may ascend to the _Absolute_, which does not depend upon a.s.sumption, the origin of scientific truth.
_The reason takes hold of this first principle of truth_, and availing itself of all the connections and relations of this principle, it proceeds to the conclusion--using no sensible image in doing this, but contemplates the _idea alone_; and with these ideas the process begins, goes on, and terminates.
"I apprehend," said Glaucon, "but not very clearly, for the matter is somewhat abstruse. _You wish to prove that the knowledge which by the reason, in an intuitive manner, we may acquire of real existence and intelligible things is of a higher degree of certainty than the knowledge which belongs to what are commonly called the Sciences_. Such sciences, you say, have certain a.s.sumptions for their basis; and these a.s.sumptions are by the student of such sciences apprehended not by sense, but by a mental operation--by conception.
"But inasmuch as such students ascend no higher than a.s.sumptions, and do not go to the first principles of truth, they do not seem to have true knowledge, intellectual insight, intuitive reason, on the subjects of their reasonings, though the subjects are intelligible things. And you call this habit and practice of the geometers and others by the name of JUDGMENT (d?????a), not reason, or insight, or intuition--taking judgment to be something between opinion, on the one side, and intuitive reason, on the other.
"You have explained it well," said I. "And now consider these four kinds of things we have spoken of, as corresponding to four affections (or faculties) of the mind. INTUITIVE REASON (???s??), the highest; JUDGMENT (d?????a)(or _discursive reason_), the next; the third, BELIEF (p?st??); and the fourth, CONJECTURE, or _guess_ (e??as?a); and arrange them in order, so that they may be held to have more or less certainty, as their objects have more or less truth."[532] The completeness, and even accuracy of this cla.s.sification of all the objects of human cognition, and of the corresponding mental powers, will be seen at once by studying the diagram proposed by Plato, as figured on the opposite page.
[Footnote 532: "Republic," bk. vi. ch. xx. and xxi.]
PLATONIC SCHEME OF THE OBJECTS OF COGNITION, AND THE RELATIVE MENTAL POWERS ___________________________________________________________________________ | | | VISIBLE WORLD | INTELLIGIBLE WORLD | (the object of Opinion--d??a). |(the object of Knowledge or | | Science--?p?tt??).
|_________________________________|____________________________ | | | | | Things. | Images. | Intuitions. | Conceptions.
____________|________________|________________|______________|_____________
And may be thus further expanded: ___________________________________________________________________________ | | | VISIBLE WORLD. | INTELLIGIBLE WORLD.
____________|_________________________________|____________________________ | | | | | Things | Images | Ideas | Conceptions OBJECT | | | | | ??a. ?.t.?. | ????e?. | ?dea?. | d?e???ata.
____________|________________|________________|_____________|______________ | | | | | Belief. | Conjecture. | Intuition. |Demonstration.
PROCESS | | | | | p??t??. | e?kas?a. | ???s??. | ?p?s????.
____________|________________|________________|_____________|______________ | | | | | SENSATION. | PHANTASY. | INTUITIVE | DISCURSIVE FACULTY | | | REASON. | REASON.
| ais??s??. | ?a?tas?a. | ????. | ?????.
____________|________________|________________|_____________|______________ | | | | MODERN | SENSE. | IMAGINATION. | REASON. | JUDGMENT.
NOMENCLATURE|Presentative |Representative |Regulative | Logical | Faculty. | Faculty | Faculty. | Faculty.
____________|________________|________________|_____________|______________ | | | MEMORY. | REMINISCENCE | ???. | a?a?s??.
| The Conservative Faculty-- | The Reproductive Faculty-- | "the preserver of sensation" |"the recollection of the | (s?t???a a?s??, se??.) [533] | things which the soul | | saw (in Eternity) when | | journeying in the train of | | the Deity."[534]
|[Footnote 533: "Philebus," -- 67] | [Footnote 534: Phaedrus, | | -- 62.]
____________|_________________________________|____________________________
The foregoing diagram, borrowed from Whewell, with some modifications and additions we have ventured to make, exhibits a perfect view of the Platonic scheme of the _cognitive powers_--the faculties by which the mind attains to different degrees of knowledge, "having more or less certainty, as their objects have more or less truth."[535]
1st. SENSATION (a?s??s??).--This term is employed by Plato to denote the pa.s.sive mental states or affections which are produced within us by external objects through the medium of the vital organization, and also the cognition or vital perception or consciousness[536] which the mind has of these mental states.
2d. PHANTASY (fa?tas?a).--This term is employed to describe the power which the mind possesses of imagining or representing whatever has once been the object of sensation. This may be done involuntarily as "in dreams, disease, and hallucination,"[537] or voluntarily, as in reminiscence. Fa?t?sata are the images, the life-pictures (?????f?a) of sensible things which are present to the mind, even when no external object is present to the sense.
[Footnote 535: "Republic," bk. vii. ch. xix.]
[Footnote 536: "In Greek philosophy there was no term for "consciousness" until the decline of philosophy, and in the latter ages of the language. Plato and Aristotle, to say nothing of other philosophers, had no special term to express the knowledge which the mind has of the operation of its own faculties, though this, of course, was necessarily a frequent matter of consideration. Intellect was supposed by them to be cognizant of its own operations.... In his "Theaetetus" Plato accords to sense the power of perceiving that it perceives."--Hamilton"s "Metaphysics," vol. i. p. 198 (Eng. ed.).]
[Footnote 537: "Theaetetus," -- 39.]
The conjoint action of these two powers results in what Plato calls _opinion_ (d??a). "Opinion is the complication of memory and sensation.
For when we meet for the first time with a thing perceptible by a sense, and a sensation is produced by it, and from this sensation a memory, and we subsequently meet again with the same thing perceived by a sense, we combine the memory previously brought into action with the sensation produced a second time, and we say within ourselves [this is] Socrates, or a horse, or fire, or whatever thing there may be of such a kind. Now this is called _opinion_, through our combining the recollection brought previously into action with the sensation recently produced. And when these, placed along each other, agree, a true opinion is produced; but when they swerve from each other, a false one."[538] The d??a of Plato, therefore answers to the experience, or the _empirical knowledge_ of modern philosophy, which is concerned only with appearances (phenomena), and not with absolute realities, and can not be elevated to the dignity of _science_ or real knowledge.
We are not from hence to infer that Plato intended to deny all reality whatever to the objects of sensible experience. These transitory phenomena were not real existences, but they were _images_ of real existences. The world itself is but the image, in the sphere of sense, of those ideas of Order, and Proportion, and Harmony, which dwell in the Divine Intellect, and are mirrored in the soul of man. "Time itself is a moving image of Eternity."[539] But inasmuch as the immediate object of sense-perception is a representative image generated in the vital organism, and all empirical cognitions are mere "conjectures" (e??as?a?) founded on representative images, they need to be certified by a higher faculty, which immediately apprehends real Being (t? ??). Of things, as they are in themselves, the senses give us no knowledge; all that in sensation we are conscious of is certain affections of the mind (p????); the existence of self, or the perceiving subject, and a something external to self, a perceived object, are revealed to us, not by the senses, but by the reason.
[Footnote 538: Alcinous, "Introduction to the Doctrine of Plato," p.
247.]
[Footnote 539: "Timaeus," -- 14.]
3d. JUDGMENT (d?????a, ?????), _the Discursive Faculty, or the Faculty of Relations_.--According to Plato, this faculty proceeds on the a.s.sumption of certain principles as true, without inquiring into their validity, and reasons, by deduction, to the conclusions which necessarily flow from these principles. These a.s.sumptions Plato calls hypotheses (?p???se??). But by hypotheses he does not mean baseless a.s.sumptions--"mere theories--"but things self-evident and "obvious to all;"[540] as for example, the postulates and definitions of Geometry.
"After laying down hypotheses of the odd and even, and three kinds of angles [right, acute, and obtuse], and figures [as the triangle, square, circle, and the like], he _proceeds on them as known, and gives no further reason about them_, and reasons downward from these principles,"[541] affirming certain judgments as consequences deducible therefrom.
[Footnote 540: "Republic," bk. vi. ch. xx.]
[Footnote 541: Ibid., bk. vi. ch. xx.]
All judgments are therefore founded on _relations_. To judge is to compare two terms. "Every judgment has three parts: the subject, or notion about which the judgment is; the predicate, or notion with which the subject is compared; and the copula, or nexus, which expresses the connection or relation between them.[542] Every act of affirmative judgment a.s.serts the agreement of the predicate and subject; every act of negative judgment a.s.serts the predicate and subject do not agree. All judgment is thus an attempt to reduce to unity two cognitions, and reasoning (?????es?a?) is simply the extension of this process. When we look at two straight lines of equal length, we do not merely think of them separately as _this_ straight line, and _that_ straight line, but they are immediately connected together by a comparison which takes place in the mind. We perceive that these two lines are alike; they are of equal length, and they are both straight; and the connection which is perceived as existing between them is a _relation of sameness or ident.i.ty._[543] When we observe any change occurring in nature, as, for example, the melting of wax in the presence of heat, the mind recognizes a causal efficiency in the fire to produce that change, and the relation now apprehended is a _relation of cause and effect_[544] But the fundamental principles, the necessary ideas which lie at the basis of all the judgments (as the ideas of s.p.a.ce and time, of unity and ident.i.ty, of substance and cause, of the infinite and perfect) are not given by the judgment, but by the "highest faculty"--"the _Intuitive Reason_,[545] which is, for us, the source of all unhypothetical and absolute knowledge.
[Footnote 542: Thompson"s "Laws of Thought," p. 134.]
[Footnote 543: "Phaedo," ---- 50-57, 62.]
[Footnote 544: "Timaeus," ch. ix.; "Sophocles," -- 109.]
[Footnote 545: "Republic," bk. vi. ch. xxi.]
The knowledge, therefore, which is furnished by the Discursive Reason, Plato does not regard as "real Science." "It is something between Opinion on the one hand, and Intuition on the other."[546]
[Footnote 546: Ibid., bk. vi. ch. xxi.]
4th. REASON (?????)--_Intuitive Reason_, is the organ of self-evident, necessary, and universal Truth. In an immediate, direct, and intuitive manner, it takes hold on truth with absolute certainty. The reason, through the medium of _ideas_, holds communion with the world of real Being. These ideas are the _light_ which reveals the world of unseen realities, as the sun reveals the world of sensible forms. "_The idea of the good_ is the _sun_ of the Intelligible World; it sheds on objects the light of truth, and gives to the soul that knows, the power of knowing."[547] Under this light, the eye of reason apprehends the eternal world of being as truly, yes more truly, than the eye of sense apprehends the world of phenomena. This power the rational soul possesses by virtue of its having a nature kindred, or even h.o.m.ogeneous with the Divinity. It was "generated by the Divine Father," and, like him, it is in a certain sense "_eternal_."[548] Not that we are to understand Plato as teaching that the rational soul had an independent and underived existence; it was created or "generated" in eternity,[549]
and even now, in its incorporate state, is not amenable to the conditions of time and s.p.a.ce, but, in a peculiar sense, dwells in eternity; and therefore is capable of beholding eternal realities, and coming into communion with absolute beauty, and goodness, and truth--that is, with G.o.d, the _Absolute Being_.
[Footnote 547: Ibid., bk. vi. ch. xix.; see also ch. xviii.]
[Footnote 548: The reader must familiarize himself with the Platonic notion of _"eternity" as a fixed state out of time existing contemporaneous with one in time_, to appreciate the doctrine of Plato as stated above. If we regard his idea of eternity as merely an indefinite extension of time, with a past, a present, and a future, we can offer no rational interpretation of his doctrine of the eternal nature of the rational essence of the soul. An eternal nature "generated" in a "past" or "present" time is a contradiction. But that was not Plato"s conception of "eternity," as the reader will discover on perusing the "Timaeus" (ch. xiv.). "G.o.d resolved to create a moving image of eternity, and out of that eternity which reposes in its own _unchangeable unity_ he framed an eternal image moving according to numerical succession, which we call _Time_. Nothing can be more inaccurate than to apply the terms, _past, present, future_, to real Being, which is immovable. Past and future are expressions only suitable to generation which proceeds through time." Time reposes on the bosom of eternity, as all bodies are in s.p.a.ce.]
[Footnote 549: "Timaeus," ch. xvi., and "Phaedrus," where the soul is p.r.o.nounced ???? d? ?????t??.]