Theory of Forms: Criticism
The Parmenides is one of Plato's later dialogues. It recalls a meeting that Socrates, Parmenides, and Zeno had in Athens sometime around 450 B.C., when Socrates was about 20 years old and Parmenides was well into old age (possibly 65, according to the dialogue). Parmenides was one of the greatest of the pre-Socratic philosophers -- someone, as Socrates put it, with "a glorious depth of mind."
The first half of the Parmenides exposes some of the weaknesses in the Theory of Forms; the second half amounts to a long-winded, rambling soliloquy, with Parmenides meticulously explaining what the 'one' is and isn't. The reader is subjected to such passages as this:
"So sameness will never be in what is different, nor difference in what is the same. And if difference will never be in what is the same, there is nothing that is in which difference is present for any length of time, for if it were in something for any length of time whatsoever, during that time difference would be in what is the same. And since it is never in what is the same, difference can never be in anything that is, and consequently neither in the 'not-ones' nor in the one."
The dialogue ends without a resolution. The reader is left to wonder whether Plato rejects the Theory of Forms, or whether the theory can be salvaged if the problems Parmenides highlights can be addressed. Most commentators believe that Plato didn't demolish his forms, and point to the fact that later dialogues such as the Timaeus take up and defend the theory. Some, however, dispute the date in which the Timaeus was composed, suggesting it may have been written before the Parmenides. Nearly all are agreed that the dialogue reflects Plato's keen desire always to get at the truth, even if this means subjecting his own cherished views to the most relentless scrutiny (as Bertrand Russell puts it, the dialogue "contains one of the most remarkable cases in history of self-criticism by a philosopher"). There is in the dialogue a moral expressed mid-way through: Parmenides the old sage tells the young Socrates that he must, if he wishes to advance far in philosophy, learn to think out the consequences of his statements and cultivate an appreciation for what can be said always on the other side.
So what are the weaknesses in the theory?
It is important to recall that Plato sees a form as the ideal essence of something, a transcendent entity that is perfect, immutable, indivisible. The things of our everyday world are imperfect copies of the forms; they are multiple, but the forms themselves are one. For example, there are many different kinds of cats: some have black fur, some grey, others orange. There are many different breeds, and cat owners might say that every cat has his own distinct personality. There is, however, something that all cats have, namely, cat-ness. According to Plato, the many cats are merely a facsimile of the form Cat. We call all the different cats in the world by one name because they have that form in common.
Plato believed that Forms exist as essences in a transcendental, or 'supralunar,' world. They are apprehensible rather than sensible, and constitute the objects of our knowledge.
The chief problem, Parmenides says, is figuring out the exact relationship between the form and the particular. How does a particular partake in the form? How is the form incarnated in the particular? Consider again the example of cats. How can the form Cat be infused in each individual cat while remaining indivisible and one? How does the perfect ideal intermingle with its imperfect copy?
A second problem is one of limits. Of how many particular things in the world can it be said that there's a form? Socrates would say that there is a form for beauty, for truth, virtue and justice, and for any number of other things (fire, water, cats, dogs). But Parmenides wonders if there's also a form for hair and mud and dirt. Socrates concedes, "I have often been puzzled about those things, Parmenides, whether one should say that the same thing is true in their case or not."
At one point Socrates suggests that "these forms are as it were patterns fixed in the nature of things. The other things are made in their image and are likenesses, and this participation they come to have in the forms is nothing but their being made in their image."
"Well," Parmenides says, "if a thing is made in the image of the form, can that form fail to be like the image of it, in so far as the image was made in its likeness? If a thing is like, must it not be like something that is like it?"
"It must," says Socrates.
Will not, Parmenides says, "that in which the like things share, so as to be alike, be just the form itself that you spoke of?"
"Certainly," Socrates replies.
"If so," Parmenides concludes, "nothing can be like the form, nor can the form be like anything. Otherwise a second form will always make its appearance over and above the first form, and if that second form is like anything, yet a third. And there will be no end to this emergence of fresh forms, if the form is to be like the thing that partakes of it."
[The Parmenides can be found in Plato: The Collected Dialogues, ed. by Edith Hamilton and Huntington Cairns, published by Princeton University Press, 1989. The quotes can be found on pp. 924, 927, and 930. Werner Heisenberg, a twentieth-century physicist, wrote a chapter in one of his books defending Plato's idealism against a materialist view of the universe. Those interested in his argument should see chapter 4 of Ken Wilber, Quantum Questions (Boston: Shambhala, 1985).]
The following passages have been excerpted from Aristotle's Metaphysics, as found in The Basic Works of Aristotle, ed. Richard McKeon (New York: Random House, 1941), pp. 706-708, 711. This is but a glimpse of a long and thorough critique. (NB: Aristotle is here using the words "Forms" and "Ideas" interchangeably.)
"...of the ways in which we prove that the Forms exist, none is convincing; for from some no inference necessarily follows, and from some arise Forms even of things of which we think there are no Forms. For according to the arguments from the existence of the sciences there will be Forms of all things of which there are sciences, and according to the 'one over many' argument there will be Forms even of negations, and according to the argument that there is an object for thought even when the thing has perished, there will be Forms of perishable things; for we have an image of these. Further, of the more accurate arguments, some lead to Ideas of relations, of which we say there is no independent class, and others introduce the 'third man'...
"And in general the arguments for the Forms destroy the things for whose existence we are more zealous than for the existence of the Ideas; for it follows that not the dyad but number is first, i.e. that the relative is prior to the absolute -- besides all the other points on which certain people by following out the opinions held about the Ideas have come into conflict with the principles of the theory.
"Further, according to the assumption on which our belief in the Ideas rests, there will be Forms not only of substances but also many other things (for the concept is single not only in the case of substances but also in the other cases, and there are sciences not only of substance but also of other things, and a thousand other such difficulties confront them). But according to the necessities of the case and the opinions held about the Forms, if Forms can be shared in, there must be Ideas of substances only. For they are not shared in incidentally, but a thing must share in its Form as in something not predicated of a subject (by 'being shared in incidentally' I mean that e.g. if a thing shares in 'double itself', it shares also in 'eternal', but incidentally; for 'eternal' happens to be predicable of the 'double'). Therefore the Forms will be substance; but the same terms indicate substance in this and in the ideal world (or what will be the meaning of saying that there is something apart from the particulars -- the one over many?). And if the Ideas and the particulars that share in them have the same form, there will be something common to these; for why should '2' be one and the same in the perishable 2's or in those which are many but eternal, and not the same in the '2 itself' as in the particular 2? But if they have not the same form, they must have only the name in common, and it is as if one were to call both Callias and a wooden image a 'man', without observing any community between them.
"Above all one might discuss the question what on earth the Forms contribute to sensible things, either to those that are eternal or to those that come into being and cease to be. For they cause neither movement nor any changes in them. But again they help in no wise either towards the knowledge of the other things (for they are not even the substance of these, else they would have been in them), or towards their being, if they are not in the particulars which share in them; though if they were, they might be thought to be causes, as white causes whiteness in a white object by entering into its composition. But this argument, which first Anaxagoras and later Eudoxus and certain others used, is very easily upset; for it is not difficult to collect many insuperable objections to such a view.
"But, further, all other things cannot come from the Forms in any of the usual senses of 'from'. And to say that they are patterns and the other things share in them is to use empty words and poetical metaphors. For what is it that works, looking to the Ideas? And anything can either be, or become, like another without being copied from it, so that whether Socrates exists or not a man like Socrates might come to be; and evidently this might be so even if Socrates were eternal. And there will be several patterns of the same thing, and therefore several Forms; e.g. 'animal' and 'two-footed' and also 'man himself' will be Forms of man. Again, the Forms are patterns not only of sensible things, but of Forms themselves also; i.e., the genus, as genus of various species, will be so; therefore the same thing will be pattern and copy.
"Again, it would seem impossible that the substance and that of which it is the substance should exist apart; how, therefore, could the Ideas, being the substances of things, exist apart? In the Phaedo the case is stated in this way -- that the Forms are causes both of being and of becoming; yet when the Forms exist, still the things that share in them do not come into being, unless there is something to originate movement; and many other things come into being (e.g. a house or a ring) of which we say there are no Forms. Clearly, therefore, even the other things can both be and come into being owing to such causes as produce the things just mentioned...
"In general, though philosophy seeks the cause of perceptible things, we have given this up (for we say nothing of the cause from which change takes its start), but while we fancy we are stating the substance of perceptible things, we assert the existence of a second class of substances, while our account of the way in which they are the substances of perceptible things is empty talk; for 'sharing,' as we said before, means nothing."
(NB: The word "idea" can be used interchangeably with "form.")
"Plato's doctrine of ideas [forms] contains a number of obvious errors. But in spite of these it marks a very important advance in philosophy, since it is the first theory to emphasise the problem of universals, which, in varying forms, has persisted to the present day. Beginnings are apt to be crude, but their originality should not be overlooked on this account. Something remains of what Plato had to say, even after all necessary corrections have been made. The absolute minimum of what remains, even in the view of those most hostile to Plato, is this: that we cannot express ourselves in a language composed wholly of proper names, but must have also general words such as 'man,' 'dog,' 'cat'; or, if not these, then relational words such as 'similar,' 'before,' and so on. Such words are not meaningless noises, and it is difficult to see how they can have meaning if the world consists entirely of particular things, such as are designated by proper names. There may be ways of getting round this argument, but at any rate it affords a prima facie case in favour of universals. I shall provisionally accept it as in some degree valid. But when so much is granted, the rest of what Plato says by no means follows.
"In the first place, Plato has no understanding of philosophical syntax. I can say 'Socrates is human,' 'Plato is human,' and so on. In all these statements, it may be assumed that the word 'human' has exactly the same meaning. But whatever it means, it means something which is not of the same kind as Socrates, Plato, and the rest of the individuals who compose the human race. 'Human' is an adjective; it would be nonsense to say 'human is human.' He thinks that beauty is beautiful; he thinks that the universal 'man' is the name of a pattern created by God, of whom actual men are imperfect and somewhat unreal copies. He fails altogether to realize how great is the gap between universals and particulars; his 'ideas' are really just other particulars, ethically and aesthetically superior to the ordinary kind. He himself, at a later date, began to see this difficulty, as appears in the Parmenides, which contains one of the most remarkable cases in history of self-criticism by a philosopher.
"The Parmenides is supposed to be related by Antiphon (Plato's half-brother), who alone remembers the conversation, but is now only interested in horses. They find him carrying a bridle, and with difficulty persuade him to relate the famous discussion between Parmenides, Zeno, and Socrates. This, we are told, took place when Parmenides was old...Zeno in middle life...and Socrates quite a young man. Socrates expounds the theory of ideas [forms]; he is sure that there are ideas of likeness, justice, beauty, and goodness; he is not sure that there is an idea of man; and he rejects with indignation the suggestion that there could be ideas of such things as hair and mud and dirt -- though, he adds, there are times when he thinks that there is nothing without an idea. He runs away from this view because he is afraid of falling into a bottomless pit of nonsense...
"Parmenides proceeds to raise difficulties. (a) Does the individual partake of the whole idea, or only of a part? To either view there are objections. If the former, one thing is in many places at once; if the latter, the idea is divisible, and a thing which has a part of smallness will be smaller than absolute smallness, which is absurd. (b) When an individual partakes of an idea, the individual and the idea are similar; therefore there will have to be another idea, embracing both the particulars and the original idea. And there will have to be yet another, embracing the particulars and the two ideas, and so on ad infinitum. Thus every idea, instead of being one, becomes an infinite series of ideas. (This is the same as Aristotle's argument of the 'third man.') (c) Socrates suggests that perhaps ideas are only thoughts, but Parmenides points out that thoughts must be of something. (d) Ideas cannot resemble the particulars that partake of them, for the reason given in (b) above. (e) Ideas, if there are any, must be unknown to us, because our knowledge is not absolute. (f) If God's knowledge is absolute, He will not know us, and therefore cannot rule us.
"Nevertheless, the theory of ideas is not wholly abandoned. Without ideas, Socrates says, there will be nothing on which the mind can rest, and therefore reasoning will be destroyed. Parmenides tells him that his troubles come of lack of previous training, but no definite conclusion is reached...
"There is one respect in which Plato's metaphysic is apparently different from that of Parmenides. For Parmenides there is only the One; for Plato, there are many ideas. There are not only beauty, truth, and goodness, but, as we saw, there is the heavenly bed, created by God; there is a heavenly man, a heavenly dog, a heavenly cat, and so on through a whole Noah's ark. All this, however, seems, in the Republic, to have been not adequately thought out. A Platonic idea or form is not a thought, though it may be the object of a thought. It is difficult to see how God can have created it, since its being is timeless, and he could not have decided to create a bed unless his thought, when he decided, had had for its object that very Platonic bed which we are told he brought into existence. What is timeless must be uncreated. We come here to a difficulty which has troubled many philosophic theologians. Only the contingent world, the world in space and time, can have been created; but this is the every-day world which has been condemned as illusory and also bad. Therefore the Creator, it would seem, created only illusion and evil. Some Gnostics were so consistent as to adopt this view; but in Plato the difficulty is still below the surface, and he seems, in the Republic, to have never become aware of it."