Platonism: … a type of metaphysical philosophy, one directed toward a transcendent reality. The rationalistic aspect: a belief in the power of thought directly to grasp transcendent realities (e.g., forms, mathematical objects); logic and mathematics are seen as providing keys to the structure of the universe. Includes belief in degrees of reality, and belief in the immortality of souls – Platonism is opposed to anything that can be called materialism; it affirms that a system of moral conceptions will reflect the nature of the universe; morality is more than merely human.

[From the Encyclopedia of Philosophy, Collier-MacMillan, 1967, vol. 6, ed. Paul Edwards]

What can we say to the claim that Plato’s philosophy characterizes the best of philosophy, or that Plato’s wisdom is “the proper domain of philosophy”? Let’s start by considering what one might mean when one makes a claim regarding the nature of philosophy.

When people claim that ‘philosophy’ is one thing as opposed to another thing they might be speaking in one of two modes:

Descriptive mode: When we try to state what the institution or discipline of philosophy is, i.e., what kinds of philosophers, philosophies, teachings, perspectives, university courses in philosophy there have been.

Prescriptive mode: When we recommend what we think philosophy should be: e.g., as when someone claims that genuine philosophy is based on the metaphysical/epistemological position indicated by Plato’s Divided Line analogy.

The Question of Platonism: Is philosophy (in general) a form of Platonism (or as Whitehead said, “a series of footnotes to Plato”)?

The Descriptive Claim:

Taken as the descriptive statement, the claim that philosophy is a form of Platonism is simply false. The work, activity or discipline of philosophy features a variety of perspectives, of which only a few can be called Platonism. Even Aristotle, a student of Plato, did not develop a philosophy that was faithful in important respects to the teachings of Plato’s Dialogues. There have been and currently are many different lines of philosophy which are very anti-Platonistic in their perspective: materialistic philosophies, Atomistic philosophies. Epicureanism, Stoicism, Modern Skepticism, Positivism, Analytical philosophies, Existentialism, … to name just a few. Some of our great figures in the history of Western philosophy, e.g., Epicurus, Spinoza, David Hume, F. Nietzsche, John Dewey, Bertrand Russell, Jean P. Sartre, and Ludwig Wittgenstein, advanced what can be called an anti-Platonistic approach to philosophical problems and issues. Only a few of the courses taught at university and college departments of philosophy can be called courses in Plato or Platonism. The majority professors of philosophy do not teach Platonism; and most likely the majority of people who practice philosophy do not identify themselves as Platonists.

In short, when considering the question, Is Philosophy a form of Platonism? most of us would answer in the negative. “No,” philosophy is not generally identifiable as a form of Platonism, nor as “a series of footnotes to Plato.” Much of philosophy that is actually practiced and taught by people can actually be seen as a counter-thesis to Platonism.

The Prescriptive Claim:

So what about the prescriptive statement? Do we have reasons for agreeing that good philosophy should be a form of Platonism? Do we have good reasons for assenting to the view that good philosophy will base itself on Plato’s Analogy of the Divided line?

When people like Whitehead and Uebersax state the case for Platonism as the key to genuine philosophy, we should understand their statements as prescriptive statements; they’re telling us what they believe philosophy should be. Admittedly, the Whitehead quotation often cited suggests a descriptive claim:

“The safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato.”

A. N. Whitehead, Process and Reality, 1929.

As a descriptive claim, this is simply false, unless we qualify it so that “a series of footnotes to Plato” include counter arguments to Plato. But we normally don’t describe contrary philosophies as “footnotes to each other.

So, I prefer to read Whitehead as a recommendation of what he best of European philosophy should be, i.e., as a prescriptive statement. This is how I shall interpret other statements in favor of Platonism: e.g., “Plato’s wisdom is the proper domain of philosophy”; “Plato’s Divided Line Analogy is the best way to deal with epistemological and ethical issues.”
[The Divided Line Analogy is given in Plato’s Republic, at Book VI, the four stages of cognition, “Speaking through the character of Socrates, Plato divides human knowledge, and its related cognitive activities, into four categories. From poorest to best, these are: eikasia, pistis, dianoia, and noesis.”]

So what are we to make of these recommendations? If there is a case to be made for Platonism as the philosophy of choice, it is a weak case. If we concentrate only on the Divided Line Analogy, we find that it is based on a specific metaphysics and epistemology, Both Plato’s metaphysics and his theory of knowledge are very questionable, to say the least.

First, consider Plato’s metaphysics. Unless we are already committed to Platonism as a philosophy, we don’t find very good arguments supporting Plato’s other world metaphysics. The arguments in Plato’s Dialogues for the necessity of a realm of eternal, unchanging forms are not cogent or sound arguments. Much in the dialogues assumes, rather than argues for the reality of a soul, separate from the body. What scientific grounds or sound philosophical arguments are there for adopting this dualistic doctrine of human reality, that essentially we are eternal souls separate from our body? What grounds – philosophical or scientific – do we have for asserting a separate, higher reality of eternal, unchanging forms? Unless we are already inclined to accept this notion of a higher separate reality, as many spiritually inclined, religious people and some mathematicians are, we shall find little or no reason for affirming such a view of reality.

Accepting Plato’s realm of eternal forms would imply that we reject the reality of modern scientific perspective of a world of evolving animal and plant life, a world of constant, dynamic change as described by astronomy, cosmology, physics, chemistry, biology, anthropology, history, and sociology. Many of us find the case for doing that to be far from convincing. In addition, Darwinian evolution by natural selection is a direct, scientific refutation of essentialism in biology; hence, it is a direct refutation of Platonism insofar as it could apply to the biosphere.

At best, Plato’s metaphysics applies to a particular philosophy of mathematics. Many mathematicians are Platonists of sorts, but the work of mathematics does not entail a Platonist metaphysics, since there are alternative philosophies of mathematics.

Likewise, the case for Plato’s theory of knowledge is a weak one. The notion of knowledge, as embodied in the Divided Line Analogy, assumes that ‘knowledge’ can be understood as a cognitive state, that it is characterized by the object of the cognitive state, and that genuine knowledge is infallible and mathematically certain. All of these propositions concerning human knowledge are questionable, to say the least. There is much work of analytical philosophers which denies these notions. First, as Gilbert Ryle, Richard Rorty and other writers on epistemological issues have argued, knowledge cannot be adequately described as a state of mind, even when it is labeled a “cognitive state.” Briefly, this is because propositional knowledge requires that something is a fact apart from the subject’s state of mind; and knowledge identifiable as a capability (knowing how to do something) requires being able to do something, not just indulge a cognitive state of mind.

“What is knowledge? Whether or not knowledge involves belief, the distinction between knowledge and belief should not be seen as a distinction between states of mind. The truth conditions of statements about knowledge must include reference to things other than states of mind . . . …being sure is not by any means necessary to knowledge, even if in the majority of cases people who know things are also sure of them. . . There are no grounds for supposing that knowledge is a conscious activity or state, nor for supposing that knowledge and awareness are the same. …

[D.W. Hamlyn, The Theory of Knowledge, Anchor Books, 1970, p. 95]

Secondly, as the twentieth century English philosopher D.W. Hamlyn points out, the view that knowledge must be infallible and mathematically certain is based on a confusion:

It is to say that we cannot both know and be wrong. Nothing follows from this about whether what we know must be such that it is impossible to be wrong about it. . . To suppose that it does is to mistake the role that “cannot” plays in “if I know, I cannot be wrong.” In fact, “cannot” merely expresses the incompatibility between knowledge and being wrong; it does not say that the only appropriate objects of knowledge are things about which it is impossible to be wrong.

[Hamlyn, ibid, p. 12]

That my ‘knowing that X’ implies that I cannot be wrong about X follows from the correct application of the concept “knowledge.” We don’t say that we know the solution to a problem if we also admit that we could be wrong. But this does not mean that in order for our claim to knowing to be appropriate it must be infallible or mathematically certain. But according to Plato, genuine knowledge is only of the infallible:

However, historically Plato and others have equated knowledge and infallibility. Plato, at one stage, cast doubt on the view that perception provides knowledge. According to him, knowledge must be reserved for objects of a higher kind, the forms. Accordingly, knowledge and infallibility go together and anything that is not infallible is not a suitable subject for knowledge. . . . . The search for indubitable and infallible truths is therefore a common feature of traditional epistemology.

[Hamlyn, ibid, p. 13 ]

However, for many philosophers this represents a wrong turn in the history of epistemological philosophy. Accepting this ‘theory of knowledge’ would imply that we really do not have knowledge in many of the natural sciences, not to mention sociological and historical sciences. It would also imply that we really all of our beliefs and affirmations about empirical matters and matters of common sense do not qualify as knowledge. Except for those who subscribe to Platonism, most people are not prepared to admit Plato’s exaggerated notion of genuine knowledge.

Hence, the case for upholding Plato’s Divided Line Analogy as a key to understanding what philosophy should be (or should aspire to) is a weak case, given the problems with its metaphysical and epistemological presuppositions. A large number of philosophers rightfully dissent.