If realism is the doctrine that we have true and direct knowledge of an objective world, then the opponents of realism are those who deny this knowledge. Their grounds for denial are many and varied, but mostly the case against realism centers on three themes.
First Theme: Objections of the Skeptics
These objections constituted the brunt of the attack
against realism in ancient thought; but modern philosophy,
too, notably in Descartes and his successors, has never
wearied exploiting them. These objections primarily are
appeals to the fact of error and deception in human knowledge,
a fact of which the skeptic has at all times made much
capital. Every occurrence thereof is for him an argument
against the trustworthiness of man's cognitive faculties. If
the senses, not to say the intellect, deceive you once, they
can deceive you forever. This, in essence, is his thesis.2
Perhaps no one in modern times has developed this
theme more relentlessly than Descartes.3 He begins by questioning
the reliability of the senses. Experience, he says, is
witness that the senses sometimes deceive me; consequently,
it would seem the better part of prudence not to
trust them unreservedly. Even those sensations which, because
of their intensity or immediacy, convey the strongest
impression of objective reality must be held suspect; for in
many a dream I have had similar impressions, only to wake
and find them illusions. Nor is the taint of error confined to
the senses. Reason itself is affected, so as to lie under deception
even in mathematics; an assertion the more remarkable
that it comes from the man who honored mathematics
above all human wisdom. Yet this is outdone when Descartes,
at the height of his critical mood, entertains the
supposition that for all we know we are under the spell of
an evil genius, of some deceiving god, to the effect that we
labor under irremediable illusion in matters, even, regarded
as most certain.
For all his doubting, however, Descartes did not succumb to skepticism. The way out, he felt, had been ensured by withholding doubt from the first recognitions of the intellect, foremost from the Cogito; for, if thought, then a thinker whose existence was thus unquestionable. From this bridgehead he would launch the general recovery of human knowledge and get on with the constructive side of his philosophy. But whether this strategy saved the situation for Descartes is something else again. More to the immediate purpose is the skeptic's conjuring up of errors of knowledge to prove that the mind (the senses included) is delivered to doubt. If, to repeat, I have been deceived before, and that in my most confident moment, what possible assurance is there that I am not now deceived, now and forevermore? Error, in short, is an incontestable fact. And since it is, does not all knowledge lie discredited? The question is the skeptic's and, with him, is not rhetorical. Our answer comes later in the chapter.
Second Theme: Immanence of Knowledge 4
It is also contended by idealists generally that realism
rests on a supposition that will not stand stubborn analysis.
To illustrate the contention we may turn to the French
philosopher Hamelin, a typical idealist.5 The basis of realism,
according to this critic of it, is the duality of "being
that is thought" and "being that thinks," 6 in other words,
the duality of subject and object. On this supposition, to
think (or to have an idea) could only mean that there is in
the one (being that thinks) an image or representation of
a real attribute possessed by the other (being that is
thought). Essentially, then, knowledge would consist in
having a double of reality in the mind. Now, this manner
of regarding it goes back to simple folk, who are not given
to questioning such matters; whereas critical reflection will
show it to be a pure absurdity, on a par with the ridiculous
assertion that an image or representation is a picture inside
the mind of something outside the mind - as though one
could attain or even speak of something outside the mind.?
In a word, thought is at once subject and object, and there
is no substance to the naive disjunction of thinker and
thing thought.
But that is not all. Realism (continues Hamelin) stultifies itself quite as much as another ground, the origin of ideas. If, as in realism, ideas must originate from an object which is not the subject, this could only be explained through a kind of transitive causality, that is, through the transmission of species or qualities from the object to the mind. In this conception, it is as though the object literally sent out facsimiles of itself, which then traveled to the mind - a grossly materialistic explanation of knowledge which had made its way into philosophy as far back as Democritus and Epicurus. Happily, it was laid to rest for good by Descartes, and with it went the "winged species" of the Scholastics. Nor are matters improved by adopting the perceptionists' tactic of eliminating every intermediary between thought and reality. This avoids the absurdity of darting images, only to fall into the mystery of an unsubstantiated immediacy.
To put it squarely, there is no overcoming the difficulties of realism, and the best advice would be to give up the chimerical enterprise of trying to make good the primitive notion that thought involves a duality of thing and thought, or that what is represented in the mind has a counterpart outside the mind. The fact is that the represented is not outside the representation. Etymologically, perhaps, the representation argues a subject and object having each an existence apart from it; the real state of affairs, however, is quite the opposite. The very representation is both object and subject. (But this would make it reality itself; which is precisely what Hamelin claims for it.) The representation is being, and being is the representation.8
So much, then, for Hamelin on realism and its alternative, a typical idealism.
Third Theme: Activity of Knowledge
Opponents of realism feel themselves further justified in
the role which the mind, they are sure, exercises in the production
of knowledge, a role far different from what realists
would have us believe. For, do not the latter regard the
mind as a purely passive power, inert before an external
object which presumably acts upon it? Yet witness Kant,
who testifies that the understanding,9 far from being intuitive
(a passive spectator) is essentially active and by nature
engaged in synthesizing the presentations of sense. More
emphatic still are Fichte and Hegel who, pursuing this
Kantian premise to the finish, emerge with the absolute
idealism in which the mind is cast as pure activity, absolute
and unconditioned. Here, then, we have the self that is
self-posited, nothing whatever being presupposed - to the
self.
Proponents of these bold idealist conceptions do not want for what they feel to be solid arguments. Much is made, to cite a prime example, of certain features of scientific thought. Advances in this area are to all appearances in direct proportion to the mind's ability to project its own object (thus the argument). Nowhere is this more evident than in mathematics. The figures, symbols, and numbers which are studied are first constituted through an activity - a construction, summation, or calculation - which the mind clearly recognizes to be its own. Indeed, the mind is capable of mathematical determinations - be they quantitative, spatial, or numerical - which it cannot visualize to itself, such is its fecundity in this regard. Much the same state of affairs is seen in the experimental sciences. You will come across in an experiment only what the mind has first brought to it by way of hypothesis or directive idea. And if we go from hypotheses to general theories, in which the knowledge science has attained at a given moment is epitomized, there again we cannot but marvel at the creative fecundity of the human intellect. All of which leads to the one conclusion: in the mathematical as in the scientific endeavor, what governs the working of the human mind is the idea pure and simple, free of all determination from without. Further evidence that the mind constructs its object is found by idealists in the intellectual judgment, by common accord the perfective moment of the intellectual process. A judgment, at least a necessary one, expresses a relation which cannot possibly have been got in experience. Here, as Kant remarked apropos of the a priori judgment, the sole determining factor is the mind. Or, if you prefer Brunschvieg, the exteriority which trails the mind's judicative operation is not an exteriority at all but stems from an inborn proclivity of the thinking self. It is as though the mind, by nature denied its external object, affirmed it with a vengeance; idle protest, however, which proves that the mind has, not an external object, only the necessity to assume it. Finally, there is the argument that realism - by its doctrine that knowledge is determined by the external object - destroys or impairs the autonomy which is part and parcel of the mind's essential vitality. Materialism, which places a necessity upon every event, is obviously incompatible with the untrammeled spontaneity that marks the autonomous self. But realism comes under the like indictment, so far as it maintains the mind's initial dependence upon the external object. Allow this, and never are you truly free. Only in idealism, which dispenses with the external object, can the human person be assured of the dignity which must be claimed for it.
To sum up (for the idealists). All the aforesaid arguments, and many more besides, support but one verdict: that the human mind is all activity, free and self-determining, with not the merest dependence upon an assumedly transsubjective object.