1997 John Pepple
Established Feb. 7, 1997


By John Pepple

I. What I Believe about Plato's Late Period
II. Other Theories on the Late Period
III. The Skeptics
IV. The Unitarians and the Revisionists
V. The Significance of the Third Man for Plato
VI. Speusippus and the Third Man
VII. The Unwritten Doctrines
VIII. Plato's Answer to Speusippus
IX. Why Plato Left These Doctrines Unwritten
X. The Timaeus, Philosopher, and Laws
XI. Conclusion
XII. Notes
XIII. Comments and responses and Kenyon College Disclaimer

As can be gleaned from the title, I claim that Plato did have unwritten doctrines and that at least some of these doctrines were intended as an answer to Speusippus. We know that Speusippus refused to believe in the existence of Platonic forms,1 and there is good reason to believe (as I shall argue later) that one of his reasons for denying the existence of forms was that he accepted that notorious passage from Plato's Parmenides, the Third Man argument.2 If so, then if Plato thought this objection valid, he ought to have revised his theory. But if Plato thought the objection was invalid, then he needed either to answer this argument or, failing that, to deliver an ad hominem attack against Speusippus (for example, by finding some flaw in Speusippus' own system). Now there is little evidence that Plato ever thought the Third Man valid or that he revised his theory of forms so as to avoid it. Nor is there any evidence that Plato ever answered the Third Man argument, at least to Speusippus' satisfaction. The only information that we have about Speusippus in connection with the theory of forms is that he rejected it; we are not told that he changed his mind on this matter. So, there is no reason to believe that Plato ever answered the Third Man to Speusippus' satisfaction. Consequently, Plato had to find some sort of flaw in the system espoused by Speusippus, and the flaw that Plato found can be inferred from what Aristotle said about the unwritten doctrines. The end result of all this reasoning is that Aristotle emerges as a much more reliable interpreter of Plato than has formerly been thought.

From what I have just said, it should be clear that I take the unwritten doctrines to have arisen in Plato's late period.3 It should also be clear that I have a very different view of the late period than other scholars do. In arguing for my view of the unwritten doctrines and the late period, I will first repeat what I have just said about the late period, but in more detail. This will be followed by a brief discussion of some other views on this topic. Then I will explain what significance the Third Man argument had for Plato, followed by the reasons for believing that Speusippus accepted this argument. After that I will briefly review the content of the unwritten doctrines and canvass some scholarly opinions on them, after which I will show how Plato used these doctrines to answer Speusippus. Finally, I will show how my view of the late period explains not just the unwritten doctrines, but also a number of other puzzles such as the surprising appearance of a dialogue concerned with the sensible realm (that is, the Timaeus, assuming it is late), the absence of the Philosopher, and the appearance of the second-best political system in the Laws.

I. What I Believe about Plato's Late Period

I claim that, while during his middle period Plato had founded the Academy and developed the theory of forms, at the beginning of his late period Plato was stung by the appearance of an objection against his theory, the Third Man argument. Naturally, he strove to answer this argument, but while the answers he invented may have satisfied him, they never satisfied its chief sponsor, his own nephew Speusippus. Eventually, having failed to answer the Third Man to Speusippus' satisfaction, Plato simply suggested that the theory of forms was such a powerful and versatile theory that it could not possibly be wrong and, consequently, one day he would find an answer to it. Meanwhile, he tried to poke holes in Speusippus' system; these efforts appear in the unwritten doctrines. He also was forced to make certain adjustments elsewhere in his system of beliefs, some of which I will discuss below (see the discussion on the Laws).

II. Other Theories on the Late Period

Concerning the late period, scholars have generally divided themselves into three groups: the unitarians, the revisionists, and a new group, whose members I call the skeptics.4

The unitarians say that in the late period Plato was basically doing what he had been doing all along; he was using the theory of forms to explore certain topics, and if there was any development during this period, it was ordinary development of the sort that we might find within the middle period. Specifically, the unitarian theory says that Plato believed that, as an objection against the theory of forms, the Third Man is invalid. Consequently, there is no reason to believe that during his late period Plato experienced a crisis.

The revisionists say that during his late period, Plato was definitely in a crisis and that he was in a crisis as a result of the Third Man argument, for that argument pointed to a flaw in the theory of forms, a flaw that could be dealt with only by subjecting that theory to strong revisions. Generally, revisionists believe that Plato revised his theory in the direction of a more Aristotelian view of the forms; that is, he no longer regarded the forms as separate or as paradigms.

As an aside, let me clarify how I shall use the terms "revise," "revisionist," and "revisionism." My theory states that Plato extended his theory, and in some broad sense that means he revised it. However, when I speak of revising in this article, I will be talking about only those changes made by Plato that were intended by him to avoid being trapped by the Third Man. Since I do not think that Plato accepted the validity of this argument, then the sort of changes I think Plato made in the late period do not count as a species of revisionism, as that term has been used in recent decades.

The skeptics insist that the chronology that was developed about a century ago is based on flawed reasoning and that there can be no certainty about when any dialogue was written; accordingly, it is probably a mistake to talk about a late period. The chronology was devised by looking at style, from which scholars noticed that the dialogues fell into three broad groups. The first and earliest group (containing such dialogues as Apology and Protagoras) is often thought of as "Socratic," so called not only because of the importance within these dialogues of Socrates, but also because of other features thought to be associated with Socrates such as professions of ignorance and a concern for little beyond ethics, as well as a high level of drama suggestive of actual conversations. The implication is that in the pages of these dialogues we have the real Socrates, or else something close to the real Socrates. The middle group (containing such dialogues as Phaedo and Republic) is considerably less dramatic and is notable for the emergence of the theory of forms and its application to political philosophy, epistemology, and other branches of philosophy. Finally, there is a late group (containing such dialogues as Parmenides and Sophist), about which there has been much dispute.

The skeptics reject these results. They point out that using stylometry to determine the chronology is flawed because, first of all, someone who was so excellent a stylist as Plato was could have adopted any style at any time he was writing; accordingly, if the style of a dialogue indicates it is early, all that may mean is that Plato decided to adopt that style for that particular dialogue. Secondly, there is no guarantee that the dialogues as we have them were not subject to numerous revisions. If so, then an allegedly late dialogue like the Sophist might really be essentially early. Plato may have begun the dialogue in his early period and then set it aside. In his late period, he may have taken it up again and gotten it ready for publication; if most of his revisions at this time were stylistic, then it will look like a late dialogue, even though it is essentially an early one.

III. The Skeptics

Let me begin my discussion of these three groups of scholars with the skeptics. First of all, this skeptical argument, if it is valid, is very powerful. It prevents us from ever having any sort of chronology, for anyone who claims that some other feature besides style can be used to date the dialogues will run up against the same skeptical argument. Let us say that someone claims that feature X can be used to distinguish between early and late dialogues. Those dialogues that contain X will be early, and those that do not will be late. But because of the previous argument, feature X cannot be of any help. Any dialogue not containing X could be the revision of an early dialogue such that the process of revision removed X from the dialogue. Likewise, any dialogue containing X could be late, for Plato was quite capable of inserting X at any time. The upshot is that the skeptics' argument, if valid, condemns all chronologies.

Accordingly, I think it is quite naive of Holger Thesleff to begin by raising these skeptical points and then to insist that he can give us a chronology on the basis of some feature other than style. He appeals to the difference between what he calls reported or narrated dialogues and dramatic dialogues, with the reported dialogues being early and the dramatic dialogues being late.5 Clearly, however, any dialogue written dramatically could originally have been narrated, being revised later so as to add the dramatic frame. Thus, there is no more reason to accept Thesleff's chronology than those based on style.

Secondly, not only the skeptics, but also the revisionists and the unitarians have each dismissed some part of the testimony of Aristotle. If Aristotle is reasonably accurate on Plato's life and writings, then each of these theories is wrong. With respect to the skeptics' theory, since Aristotle gave us information about the life of Plato that suggests he went through an early Socratic period, then if Aristotle is right, the skeptics are wrong. Knowing this, the skeptics have dismissed what Aristotle said. Thesleff, for example, attacks the idea that there was an early Socratic period that Plato experienced by saying:

"The only external evidence that is sometimes referred to is Aristotle's statement in the Metaphysics that Plato's philosophy arose from a combination of Pythagoreanism and Heracliteanism with Socraticism (such as Aristotle describes it); but this is really not conclusive at all as regards the chronology of his writings."6

It is true that it is not conclusive, but it cannot be dismissed so easily. Moreover, Thesleff cannot avoid appealing to Aristotle in other circumstances, when it suits his interests. Consider his discussion of the existence of a proto-Republic that he feels must have existed in the 390s before the publication of Aristophanes' Ecclesiazusae in 392. Concerning this, he says, "The evidence of Aristotle that Plato's Socrates was the first philosopher to propose a community of women and children is quite important."7 In other words, Thesleff regards Aristotle as reliable or unreliable, depending upon his own interests and not upon any disinterested criteria.

Another skeptic who discounts Aristotle's evidence is Debra Nails. While many scholars argue that Aristotle must have had good knowledge of Plato since he was one of Plato's associates, Nails counters this argument by making an analogy with Wittgenstein and his associates: "It is natural to be reminded of the intellectual offspring of the charismatic Wittgenstein, vigorously and passionately challenging one another's memories and notes, finding nothing small or large on which all can agree."8 But surely they could all agree that the Tractatus was early!

My claim is that Aristotle can be counted on for certain things, especially when it concerns some broad or obvious claim about Plato's life and philosophy such as when things were written, what stages he went through, and whether he had a satisfactory answer to the Third Man. In this article, I intend to show that there is a plausible and consistent interpretation of both Plato's dialogues and the testimony of Aristotle, an interpretation, moreover, that treats Aristotle charitably; and since we ought to treat philosophers as great as Aristotle charitably, we ought to adopt this interpretation.

Thirdly, there seems to be a tendency among the skeptics to think that because stylistic analysis is flawed (or at least potentially flawed), therefore the chronology that results must be flawed as well. However, people occasionally get good ideas in dubious ways. The chemical structure of benzene was suggested to its discoverer (F.A. Kekule) in a dream. No one would say that its appearing to him in a dream made it true, but it turned out that it was true. Likewise, even if stylistic analysis is flawed, that is not sufficient to say that the understanding of Plato's life that we have derived from this analysis is incorrect. In particular, that understanding has a plausibility to it that I have not seen so far in anything the skeptics have proposed. (Of course, that may change in the future.) The standard chronology asserts that Plato began with a Socratic period, and given the obvious importance of Socrates in Plato's life, that seems quite sensible.

Thesleff's chronology, by contrast, seems to be based on a large number of unwarranted assumptions. Consider, for example, his argument against an early Socratic period. Thesleff argues against this by saying that Plato "must have been reflecting about Heraclitus, Anaxagoras, Parmenides, Pythagoreans and sophists long before he published dialogues such as Protagoras, Cratylus, Phaedo, and Parmenides."9 That is, the early period was not purely Socratic, for Plato must have been immersed in the doctrines of these other philosophers as well.

But this statement of Thesleff's is simply assertion without proof. It apparently is based upon the assumption that a great philosopher must have read all the classics prior to his or her time, yet that is precisely what we know that great philosophers often do not do. Consider Descartes as an example. As Marjorie Grene puts it, "In general, [Descartes] seems to be resigned to having his friends tell him he has been anticipated by St. Augustine."10 In particular, he claimed not to have read that passage in Augustine's works related to his cogito.11 As another example, consider the climate in which many of us in the analytic tradition were educated. I was discouraged from paying any attention to Continental philosophers. Why should not Socrates have discouraged Plato from paying attention to the presocratics? (There is some evidence for such a claim in Xenophon's Memorabilia at I.i.12-15 and IV.vii.5-6 and no uncontroversial evidence that I know of to the contrary.) As I said above, the traditional chronology has a plausibility to it that is lacking in other chronologies I have seen, for it is easy to see from looking at the dialogues that the most influential person in Plato's life was Socrates, not the Pythagoreans, Parmenides (who is not even mentioned in most of the dialogues), or Heraclitus.

Finally, there is good reason to believe that the Parmenides is later than the Republic, and so at least one fact about the chronology can be retrieved. We know that within the Academy there emerged a number of arguments against the forms, for these arguments are repeated by Aristotle (Metaphysics I.9). One of these was the Third Man (which also appears in the Parmenides), and it was accepted by Aristotle (and probably by Speusippus as well). Yet when Plato discussed the forms in the Republic, no such arguments are mentioned. Since at the end of Republic V Plato seemed desirous of showing that forms exist, since such a desire would necessitate a discussion of objections if they existed, and since there is no obvious reason why Plato refrained from mentioning such objections, I conclude that they did not then exist. Thus, the Republic (or at least Republic V) must have been written before the Parmenides.

IV. The Unitarians and the Revisionists

From what I said at the beginning, it should be obvious that both of these theories have a major shortcoming, namely, the failure to consider the possibility that Speusippus accepted the Third Man. On the one hand, the unitarians have insisted again and again that Plato had an answer to the Third Man. But so what? His problem was that this answer was not accepted by Speusippus. (Nor, eventually, was it accepted by Aristotle.) Plato's crisis was his failure to persuade some of his brightest students that the Third Man argument was invalid. On the other hand, the revisionists see Plato escaping from the Third Man by revising his theory in the direction of an Aristotelian view of forms. But Plato's foremost opponent at the time the Parmenides was written was not Aristotle, who was either just entering or had not yet entered the Academy,12 but Speusippus; and Speusippus did not believe in forms. As I shall argue below, he probably accepted the Third Man as well as an objection against the method of division. But there is no guarantee that these were the only arguments he used against his mentor's theory. Aristotle used a wide variety of arguments against the forms, so it is reasonable, or not unreasonable, to believe that Speusippus had a wide variety of arguments, also. Consequently, revising the theory of forms was a worthless enterprise, for there was no way to take care of all of Speusippus' objections by making revisions. The only action that would satisfy him was abandonment.

In addition, both of these theories on the late period has a strong point and a weak point; it turns out that the strong point of one theory is the weak point of the other (and vice versa). The strong point of the unitarian theory, and the weak point of the revisionist theory, is that the evidence that Plato revised his theory is almost nonexistent. Indeed, the most famous article promoting revisionism is G.E.L. Owen's article on the dating of the Timaeus (see note 4). But this article, if correct, does not provide solid evidence of revisionism; instead, it merely removes some solid evidence against it. The Timaeus had previously been thought of as one of the latest of the dialogues, and since it espouses an unrevised theory of forms, revisionism could not be a viable theory. Consequently, Owen was forced to argue that the Timaeus was not late but middle. Yet, the evidence for revisionism that remains even after placing the Timaeus in the middle period is still quite weak; moreover, the pressure was on Plato not to revise, but to abandon.

The weak point of the unitarian view, and the strong point of the revisionist view, is that it is quite clear that throughout his late period beginning with the Parmenides Plato was in a crisis. In the late dialogues the theory of forms is criticized, Socrates is demoted, Parmenides and the Eleatic Stranger appear as the main characters, the old dialectic is dropped and a new dialectic (the method of division) takes its place, one of the dialogues (the Theaetetus) reverts to the use of the elenctic method found in the early dialogues or else uses a new method (the maieutic method), and another (the Philebus) contains an ontological division of reality that resembles nothing from any other dialogue. Moreover, the late dialogues have a very different feel to them than the middle dialogues do (just as the middle dialogues have a very different feel to them than the early dialogues do.) Thus, it is reasonable to believe that during the late period Plato experienced a crisis.

But while the revisionists are on stronger ground concerning this point, the plain fact of the matter is that the evidence from the late period points to at least one other crisis. During this period Plato failed to complete at least one and likely two trilogies. While the revisionists do not accept the lateness of the Timaeus trilogy, they do accept the lateness of the Sophist triology. The absence of the third work of this trilogy, the Philosopher, points to a second crisis, an aftershock (as it were) to the main crisis that resulted from the objections against the forms in the Parmenides.13 The revisionists have never mentioned this second crisis, perhaps because it is not easy to see how, in the face of this new crisis and assuming he took this new objection to heart, Plato could still think of revising as opposed to totally abandoning the forms. I shall say more about this second crisis below.

Another point against the revisionists concerning the crisis (or crises) in Plato's late period is that they have an idee fixe on what sort of crisis it was. The revisionists believe that Plato must have felt that the Third Man was valid against his own theory and that therefore he must have engaged in revising. However, there is no evidence that Plato ever thought the Third Man argument was valid. The only remark he ever made on the subject can be found at Parmenides 135a-b, which comes from a paragraph that occurs immediately after all of the objections have been presented; consequently, it is likely that what that paragraph represents in relation to what has gone before is an appraisal or assessment. Accordingly, it is an extremely important paragraph. It does not help the revisionist cause that in this paragraph Parmenides says that someone with "considerable natural gifts" would be able to figure out that forms do exist, implying that the objections have no force.

Lest the unitarians take my remarks to show that they are right against the revisionists, let me make two remarks. First of all, although it is clear that when Plato wrote the Parmenides, he felt that he had an answer to the Third Man, he need not have continued to feel this way. Given that Aristotle felt that the Third Man was obviously valid, and given that by the end of his life (if not earlier) Plato must have realized that Aristotle had "considerable natural gifts," why would Plato refrain from writing down his reasons in favor of invalidity in as much detail as possible?

Secondly, observe that in this paragraph Parmenides says something else. Before I say what that something else is, let us try to imagine what else he would say if the unitarians or the revisionists were right. The unitarians have always taken the appearance of the Third Man to have a benign purpose. They have taken it to mean, for example, that Plato was providing the reader (or hearer) with a logical exercise in finding fallacies,14 that he was attacking some members of the Academy who had an incorrect view of the forms,15 or that he wanted to show to his young students the dangers of doing philosophy at too young an age, before having been trained in dialectic.16 If the unitarians were right, then, we would expect Parmenides to make remarks about the importance of knowing how to detect fallacies, of ensuring that one has understood the theory of forms properly, or of doing dialectic before engaging in metaphysics. (It is true that Parmenides does say something like the last of these, but that is not until 135c-d, and so that statement must be of secondary importance.) The revisionists, of course, imagine that Plato included the Third Man argument in a dialogue because it pointed to an important flaw in his theory of forms and that this flaw indicated the need to revise that theory. Consequently, if the revisionists were correct, then we would expect Parmenides to ask Socrates how he planned to revise his theory so as to avoid the Third Man and the other objections. But observe how Plato actually expressed himself in this passage. He says that when someone hears these objections, "the result is that the hearer is perplexed and contends that [forms] do not exist.... In saying this ... it is astonishingly hard to convince him to the contrary" (135a3-7). There is nothing here about detecting fallacies, attacking incorrect views on the forms, or the need for sufficient training in dialectic on the one hand, or revising the theory of forms on the other. It is all about an adverse reaction among those hearing these objections. Parmenides does not even indicate that only some hearers reacted to the objections by rejecting the forms; he appears to be indicating that all of them did (Plato, presumably, and perhaps Xenocrates being the lone exceptions). Nor should we think that these statements are just idle remarks, for they are confirmed by Aristotle. At Metaphysics 1086a2-5 and 1090a7-15 Aristotle told of someone--presumably Speusippus--who rejected the forms because of objections raised against them. We have to accept the unpleasant fact that Parmenides' statements at 135a3-7 destroy both theories. Against the unitarians, they show that the theory of forms was under heavy attack at this time. Against the revisionists, they show that Plato was under pressure not to revise his theory, but to abandon it. I take Plato's statements at 135a3-7 to be a reference to what was occurring just then in the Academy: that most of his students had been convinced by the Third Man to reject the existence of the forms and that one of the people who was "astonishingly hard to convince" that the Third Man was invalid was his own nephew Speusippus.

Another problem with both of these theories is that neither of them does much to explain some of the other phenomena of the late period such as the switch to the second-best political philosophy or the failure to finish at least one and possibly two trilogies (depending upon when the Timaeus is placed).

Still another problem for both theories is that neither can deal with the evidence from Aristotle, except by dismissing it. Let me begin with the unitarians. Aristotle spoke of the Third Man as a valid argument against the theory of forms (Metaphysics 990b17, 1038b34-1039a2, and 1079a32-b11). He did so with virtually no discussion either, and that suggests that Plato had no good answer to it. Cherniss countered this by observing that Plato did have an answer to it and that Aristotle was negligent or dishonest in refusing to acknowledge this answer. That answer, which appears at both Republic 597c and Timaeus 31a, says essentially that the Third Man cannot generate a regress since once the second form is produced, the first form no longer counts as a form. Consequently, there is no regress of forms.17

There are four problems with this response. First, there may be no regress of forms, but there certainly is a regress. At least, Aristotle and (as we shall see later) Speusippus continued to think the Third Man valid, so they are likely to have thought the regress continues. Let us consider the argument from their point of view. Since both continued to think the Third Man valid, then they probably thought along the following lines. At both Timaeus 31a and Republic 597c, the generation of a third entity presupposes that the One Over Many premise came into play. But that premise works only on those entities that are already F (whether F is large or being a bed or anything else). Accordingly, Self Predication must have been accepted by Plato. As for the Nonidentity premise, its underlying idea is that nothing can be allowed to explain its own character, whatever that character may be (except perhaps in a few exceptional cases such as unity). It is true that we may concede a difference in being between forms and sensible particulars. The latter cling so precariously to being that one may perceive a problem in their having any given feature such as largeness. If so, then Plato's motivation in introducing forms as explanations of such features is because it is difficult to see how sensible particulars can have any features at all (since they are subject to constant flux). However, Plato probably had another motivation in wishing to have forms be explanations of features such as largeness: the need for a factor to explain the appearance of such a feature in everything in which it appears. If so, then it becomes impossible to say that a form can be allowed to be the explanation for its having the feature in question. The form of Largeness cannot be used to explain why that form itself has the feature largeness, if the explanation is intended to explain largeness wherever it occurs, lest we also allow large sensibles to be their own explanations for having the feature largeness.

It is this sort of reasoning that Aristotle and Speusippus are likely to have used against Plato to show that the regress continues. His attempted escape from the Third Man in the two passages cited used the same three premises that the Third Man used; consequently, it ought to lead to a regress. The only difference is that there is an extra premise supplied by Plato that shows that at each stage only one form exists. That extra premise, which we might call the Subordination premise, states that if one entity participates in another entity so as to be F, then the first entity cannot be the form of F. Let us see how the Third Man works with this added premise. From a set of large sensibles, the One Over Many premise can be used to show that a form exists by virtue of which those sensibles are all large. By Self Predication, that form is also large. By the One Over Many premise used again, the largeness of the form Largeness must be explained by some form. By Nonidentity the form that explains why Largeness is large cannot be Largeness itself; we must posit another form of largeness. Now the Subordination premise comes into play. It says that whatever is the ultimate cause of largeness in all of reality is the form. Consequently, the second form of largeness now is dubbed the form of largeness. However, the original form of largeness still exists, even though it no longer counts as the form. But it still has the other features typically associated with forms; it is nonsensible, pure, divine, unchanging, and so on. And Self Predication applies to both it and the new form, which means that the One Over Many and Nonidentity premises will apply again in turn, which means that a new form of largeness is generated. In other words, there is good reason to believe that the regress continues.

Second, Cherniss claims that Plato's answer to the Third Man appears in the Timaeus. However, the Timaeus is part of a trilogy that was never finished, and one obvious reason why it was never finished just is that Plato's answer was not well received by his contemporaries. It is true that when Cherniss wrote, it was generally thought that the Timaeus should be placed at the end of the late period with only the Laws placed later. Since at the time that Plato wrote the Timaeus he had been in his old age, it is easy enough to imagine that he abandoned the trilogy because his advancing years forced him to make some hard choices, and the choice he decided upon was to write the Laws. But today the situation is different. Leonard Brandwood places the Timaeus near the beginning of the late period, and that leaves plenty of time for Plato to finish the trilogy. Since he did not finish it, that suggests that it was seen as problematic in some way.

It is true that Brandwood uses style to reach his conclusion, and the skeptics have caused us to doubt the value of style, but there are at least two other indications that the Timaeus comes before the Sophist, and none that it comes later. The first of these is the remark at 38b that a discussion of what is not will be dealt with in a later dialogue. That later dialogue is obviously the Sophist. Secondly, if the Timaeus is placed before the Sophist trilogy, the political philosophy of Plato undergoes a smooth progression. In the Timaeus trilogy, we get the same political philosophy as in the Republic. In the Politicus, we get the first hints of the importance of law. In the Laws, we of course get a whole dialogue on this topic. Accordingly, we can see an orderly progression if the Timaeus is placed early within the late period, but not if it is placed late within the late period.

Third, even if the Timaeus were to be later than anything except the Laws, there are enough indications that Plato was in a crisis at this time to indicate that we should be hesitant about accepting the answer to the Third Man contained therein as Plato's final word on the matter. Obviously, Aristotle was never convinced. Nor is there any indication that Speusippus was, either.

Fourth, Cherniss never considered the possibility that Speusippus accepted the Third Man (as I suggested earlier is true of most scholars). Once we consider this possibility, a problem in Cherniss's views emerges. On the one hand, Cherniss believed that Speusippus abandoned the theory of forms for a single reason, that the existence of forms conflicts with the method of division and collection. Cherniss believed that the criticism was the following:

"If the animality in the specific ideas of man and horse is one and the same thing ... then these specific ideas would have to be a numerical unit in spite of the fact that they are distinct entities and the unique idea of animal would in fact be separate from itself."18

Speusippus made the choice of keeping the method of division while rejecting the existence of forms.

On the other hand, Cherniss believed that Plato's reason for publishing the Third Man was that he wanted to show to young people in the Academy the dangers of doing metaphysics before being properly trained in dialectic.19 But once we consider the possibility that Speusippus accepted the Third Man, we see that Cherniss's views are quite implausible. For if we reject this possibility, we are supposed to believe that Plato went to the trouble of publishing some arguments in the Parmenides against the forms which apparently no one accepted, but that he refused to publish an argument against the forms which someone did accept. It is useless for Cherniss to argue that because both he and Plato think that Plato's answer to the Third Man is satisfactory, therefore Speusippus must have agreed. We already know from the debates over the last forty years that the Third Man occasions wide disagreement on its validity, and we need look no further in the ancient world than to Aristotle to find an example of someone who opposed Plato on this point; and where one person disagrees, we are likely to find another. The more plausible view, therefore, is that Speusippus did accept the Third Man, that Plato published it because he felt the need to at least acknowledge it, and that he refrained from publishing Speusippus' objection relating to the method of division because he felt it to be of lesser importance.

Let me now consider how Aristotle's testimony poses problems for the revisionists. In responding to Cherniss, who (as already mentioned) believed that Aristotle had failed to mention Plato's rebuttal to the Third Man and so must be guilty of negligence or dishonesty, Owen replied:

"Aristotle was accused of citing such regress arguments as valid against the old Forms without mentioning that Plato had, or supposed he had, rebutted them. But the reason why Aristotle is as silent as Plato himself on this vital answer is just that no answer existed."20

In this passage Owen alluded to Aristotle's silence on a particular point as evidence in favor of his theory. But Aristotle was also silent about other points, such as whether Plato had ever revised his theory in response to the Third Man. We simply never hear him saying that such a thing occurred. Throughout the Metaphysics, Aristotle often compared the views of Plato with those of Speusippus and Xenocrates, but he never compared any of Plato's revised views with the views of those other two philosophers or with Plato's old views. In addition, he certainly talked of other views that could be construed as revised versions of Plato's theory, yet he never associated those revised versions with Plato. For example, at Metaphysics 991a17 he mentioned both Anaxagoras and Eudoxus as having denied separation, but refrained from mentioning Plato. And of course Aristotle's own metaphysics can be construed as a revision of Plato's theory, but again he never associated it with Plato. Nor was Aristotle alone in refraining from speaking about Plato's having revised his theory. No one else in a position to know did this either.

Of course, it could be that Plato revised his theory in such a way that it came to resemble Aristotle's own views, and so he never felt any need to comment on this. But how likely is such a possibility? Two philosophers can always find at least one thing on which to disagree. Is it truly so likely that Aristotle's views on forms coincided so exactly with Plato's revised views that he never felt it necessary to make any sort of comment on them?

As for Owen's assertion that there was no answer possible to the Third Man, it may be true that there was no logical answer to the Third Man, but there certainly was a rhetorical answer to it. The rhetorical answer says that since the theory of forms is absolutely necessary for thought and discourse (as Parmenides 135a-b states), then the theory of forms must be true, and since it must be true, that means that there must be an answer to the Third Man, even if that answer has not been found yet. That is, the rhetorical answer insists that the failure to find an answer to the Third Man does not indicate giving up the forms so much as it indicates maintaining the hope or the faith that an answer to it will be found one day. Revisionists seem to forget that people tend to become very fond of their theories and will not give them up easily. Owen should have noticed this with Cherniss, for as far as I know, Cherniss was never persuaded by any of the new views that Owen was propounding. And I have no doubt that very few revisionists (or unitarians or skeptics) will give up their theories because of what I say in this article.

The upshot of the previous paragraphs is that the unitarians cannot explain why Aristotle treated the Third Man as an argument requiring little or no discussion, while the revisionists cannot explain why Aristotle never indicated that Plato abandoned the theory of forms or revised it in the light of the Third Man. My view of the late period explains this paradox from Aristotle. Plato never answered the Third Man to his opponents' satisfaction. However, he certainly was not going to give up a theory that he had been using fruitfully for so many years when there was always the chance that a persuasive answer to the Third Man would come to him tomorrow. This explains both why Aristotle talked of the Third Man as obviously sound, for an answer to it never did come into Plato's head, and why Plato never revised his theory of forms, for he kept hoping that an answer would.

V. The Significance of the Third Man for Plato

The significance--the primary significance, that is--of the Third Man for Plato is simple. It was the first time he had seen an intelligently constructed argument leveled against his beloved theory of forms. (By intelligently constructed, I do not mean to imply anything about the argument's validity. The ontological argument for God's existence invented by St. Anselm is intelligently constructed, but saying this entails nothing about its validity.) The reason for believing that this was the first such argument Plato had seen is also simple: if he had seen any such arguments earlier, we would have heard about it from him.

Consider the passage at the end of Republic V. Here Plato chastised the lovers of sights and sounds for refusing to accept the existence of the form of Beauty. While he developed an argument against them (beginning at 476e), he refrained from presenting their own arguments in favor of their position or against his. It is reasonable to infer either that they did not have any such arguments or that those arguments were so bad as not to be worth discussing. The absence of arguments against the forms that characterizes this passage is typical of other middle-dialogue passages as well. Consequently, the Third Man must have been the first intelligently constructed argument against the forms that Plato had seen.

VI. Speusippus and the Third Man

As far as I know, the only scholar to have made the obvious suggestion that Speusippus accepted the Third Man is R.M. Dancy. Most scholars have associated the argument with, if with anyone in the Academy, Aristotle, and this despite the fact that on the usual dating Aristotle was not even in the Academy when the Parmenides was written. There are two reasons for believing Speusippus did accept the Third Man. Dancy gives one of these explicitly, and he may give the other implicitly. He argues that the evidence that Speusippus accepted the Third Man as valid appears in Speusippus' belief that the cause of some quality in other things cannot have that quality itself in the same way.21 It was precisely the failure by Plato to accept this claim that led him to the Third Man argument, for by having forms be both causes of F and an F itself in the same sense as the other things that are F, the infinite regress begins. That is, the point of having forms be causes is that a thing's having the quality F must be explained by appeal to some other entity, but by making the form of F have the quality of F as well, we are forced to appeal to another form of F to explain why the first form of F has the quality F.

In addition, another reason for believing that Speusippus accepted the validity of the Third Man can be seen from comparing the views of Plato, Speusippus, and Xenocrates on numbers. Plato felt that three kinds of numbers exist: form numbers, mathematical numbers, and sensible numbers. (Form numbers are exemplified by, say, the Three itself; mathematical numbers are entities which are made out of a myriad of identical, separate, nonsensible units; and sensible numbers are made out of sensible units). Speusippus denied the existence of form numbers, while Xenocrates identified them with mathematical numbers. Their reasoning can be explained as follows. Speusippus accepted the Third Man and consequently eliminated all forms, including those for numbers, from his ontology. But since he was still basically a platonist (despite not wanting forms), he wanted to give importance to numbers and so he accepted mathematical numbers. Now the Third Man will not apply to these entities. First of all, the One over Many premise will not apply to these entities, for Speusippus refused to believe in the forms and so refused to accept such a premise. Secondly, even if an infinite regress were somehow to be constructed, Speusippus would simply say that there are already an infinite number of, say, mathematical two's. Xenocrates, hearing both Plato's arguments for the forms and Speusippus' line of reasoning, felt he could make a compromise. By identifying form numbers with mathematical numbers, he could preserve the essentials of both systems. Since Speusippus avoided the Third Man for two reasons, Xenocrates calculated that it was safe to avoid it for only one reason. The One over Many premise would apply to the form numbers, but since there were already infinitely many of them, an infinite regress would not hurt his theory.

VII. The Unwritten Doctrines

The unwritten doctrines refer to various things said by Aristotle and others which involve a diverse terminology and which seem to bear no relation to anything we can find in the dialogues (with the possible exception of the Philebus). Let me set out the more important of these doctrines that we can extract from various ancient commentators:

(A) There are two fundamental principles underlying everything: the One and the Indefinite Dyad. (Aristotle, Metaphysics 987b20-22 and 988a10-15)

(B) These fundamental principles somehow generate everything else, in the following order: numbers, forms, and sensible things. (Aristotle, Metaphysics 988a10-15, and Theophrastus, Metaphysics 6b10-15)

(C) Forms are generated from the One and the Dyad, sensibles from the forms and the Dyad. (Aristotle, Metaphysics 988a10-15)

(D) The One is associated (but apparently not identical) with goodness, the Dyad with evil. (Aristotle, Metaphysics 988a14-15 together with 1091b13-14)

First of all, the terminology used by both the ancients and the moderns in connection with this topic is not consistent. For one of these principles we hear of the One, Unity, and the Limit. For the other we hear of the Dyad, the Indefinite Dyad, the Indefinite Two, the Great and the Small, and the Unlimited. Whether all of these terms can be traced back to Plato's two principles or whether some of them refer to other entities derived from the two principles is uncertain.

Secondly, Aristotle made other assertions on behalf of Plato that I am going to dismiss as irrelevant or impossible to prove. For example, he insisted that Plato believed that all forms are numbers (De Anima 404b24-5), that numbers go up to the number ten only (Physics 206b32-33), and that the One is an essential cause while the Dyad is a material cause (Metaphysics 987b20-21). This last notion is due to Aristotle's having imposed his own worldview onto Plato's doctrines, which has plunged Platonic scholars into utter confusion. As for the belief that forms are numbers, I think that W.D. Ross adequately explained this as meaning that on occasion Plato would associate (but not identify) numbers with certain forms.22 It is true that these considerations have caused scholars like Cherniss to insist that Aristotle misunderstood or misrepresented Plato's thought. However, I shall show shortly that at least for the claims (A) and (B) above there is good reason to believe that Aristotle was right.

Thirdly, there is nothing wrong with saying that Plato believed that forms could be generated from two fundamental principles. This has been objected to because forms are supposed to be eternal and ungenerated.23 However, clearly the sort of generation involved is atemporal generation, just as the blending of forms in the Sophist is atemporal and so is quite different from the participation in forms that sensibles experience.

Because of the fact that these doctrines correspond to nothing in the dialogues and because Aristotle never explained the purpose of these unwritten doctrines, scholars have been in despair. At one extreme, Cherniss asserted that Aristotle misunderstood or misrepresented Plato's thought. At the other extreme, the Tubingen school has maintained that these unwritten doctrines not only were asserted by Plato, but also underlie all of his dialogues and represent his true and most important views. Let me give a quick review of various views on the unwritten doctrines.

Cherniss was adamant in believing that the unwritten doctrines were nothing but Aristotle's misinterpretations or misrepresentations of Plato's views, all of which could be found in the dialogues.24 People have whittled away at his arguments down through the years, and some have offered other interpretations of the evidence.25 Since I have already criticized some of Cherniss's views earlier, I will offer only a few remarks on Cherniss's view of the unwritten doctrines. My claim is that in certain instances of Aristotle's testimony, we have good reason to believe he is correct. One good reason for believing Aristotle is when others agreed with him. For example, when Aristotle related the story about Plato's famous lecture On the Good and asserted that in that lecture Plato talked about two fundamental principles underlying the forms, he was in good company. According to Simplicius, this was a view shared by Speusippus, Xenocrates, Heraclides, Hestiaeus, and others. Simplicius affirmed that all of these people attended Plato's lecture, took notes on that lecture, and published their notes.26 There is not a single report from antiquity saying that anyone contradicted Aristotle on the basic content of these lectures. Everyone, apparently, believed they had heard Plato say the same thing, that he believed in two fundamental principles, the One and the Indefinite Dyad. While it is logically possible that all of these people misunderstood Plato on this point, it seems highly implausible.

Another good reason for believing that Aristotle was right to impute these two principles to Plato is that he also imputed nearly the same two principles to Speusippus. (Plato believed in the One and the Indefinite Dyad, Speusippus in the One and the Plurality.27) While we may hold that Plato's two principles are somehow a distorted version of something about the forms from the Sophist,28 it is hard to see how we can believe that anyone could extract nearly the same two principles from Speusippus, given that he did not believe in forms at all.29 In addition, Aristotle imputed (B), or a variant of (B)--that is, (B) minus the forms--to Speusippus as well (Metaphysics 1087b6-9). He furthermore insisted that Speusippus' system was poorly constructed, like a bad tragedy (1090b20). Finally, Theophrastus, when discussing whose system followed most coherently from his fundamental principles, also accused Speusippus of having a poorly constructed system (Metaphysics 6a15-b17). It seems quite unlikely that anyone of Aristotle's caliber would impute two principles to Speusippus' system, claim that everything in his system was supposed to be derived from these two principles, and then denounce him for making a bad job of it. At some point the principle of charity must take over, and we must allow that Aristotle would not do such a thing.

Moreover, at Metaphysics 1087b5 Aristotle explained that Plato preferred the Dyad over the Plurality because he felt the essence of Plurality to be the Dyad (that is, that a plurality is the opposite of what is one, and the most basic way of being a plurality is to be two). It is possible that all of this is Aristotelian misunderstanding or misrepresentation, but again it seems unlikely. Anyone who wanted to impute these two principles not only to Plato but also to Speusippus, whose system is much less susceptible to such imputation, would be doing so as a way of criticism and so would not bother with such fine points concerning the exact principles chosen. It seems all too likely that we are dealing with things that Aristotle actually heard from the mouths of Plato and Speusippus.

Finally, let me reiterate a little of what I have already said against Cherniss. There is no good reason to deny that Speusippus accepted the Third Man (in fact, I know of no one who has ever even argued against it; instead, the possibility has never even been considered until recently). But once we acknowledge this, and once we look carefully at Parmenides 135a3-7, we see that Plato's reason for introducing the Third Man into a dialogue was not to emphasize to his students the need for more training in dialectic, but because the argument had taken the Academy by storm. Nearly everyone except Plato (and perhaps Xenocrates) appeared to accept it as a valid objection against the existence of forms. If so, then Plato had to acknowledge it, at least, and to answer it; but there is nothing suggesting that any answer he gave was ever considered acceptable by Speusippus. Plato's failure to finish two trilogies from this period indicates a tumultuous time for Plato and further points to his failure to satisfactorily answer the Third Man. Since there is no evidence that Plato ever revised (or abandoned) his theory of forms, he must have made an ad hominem attack against Speusippus. Since the unwritten doctrines contain the best evidence of such an attack, we ought to at least refrain from dismissing these doctrines too hastily.

Now let me turn to some other views. Gregory Vlastos believed that the unwritten doctrines were nothing but views of Plato that were never sufficiently developed to make it into print.30 The decisive point against this position is that Plato must have had a great many opinions on a great range of subjects that never made it into the dialogues. For example, we hear little about the nature of piety after the Euthyphro; are we supposed to believe that Plato had no other views on this topic? Yet the unwritten doctrines that we hear about represent only a narrow slice of possible views: on mathematics or the philosophy of mathematics, on fundamental principles and their relations to the forms, and on how those fundamental principles relate to the good.

Kenneth Sayre believes that the unwritten doctrines were part of Plato's activities in revising the theory of forms, that they can be found in the Philebus, and that scholars up till now have not noticed this because Aristotle used a different terminology to describe these doctrines from what is used in that dialogue. In particular, he believes that Plato adopted these doctrines so as to help him relinquish the view that forms are separate.31 While I am inclined to agree that these doctrines can be found in the Philebus, I am skeptical that they represent a revision of the theory of forms. Against this, first of all, Aristotle, the main source for our knowledge of the unwritten doctrines, never suggested that Plato changed his mind on the forms' separateness.32 At Metaphysics 991a17 he mentioned both Anaxagoras and Eudoxus as having denied separation, but refrained from mentioning Plato, which is unlikely if Plato had denied separation. Secondly, the idea of using these fundamental principles to solve the problem of separation (if Plato even thought of it as a problem) is quite suspect. If the problem of separation was that forms were separate from sensibles in the sense of being transcendent (which would make it difficult to think of them as causes), then that problem is solved by refusing to separate them from sensibles. If the problem of separation was a problem caused by making forms independent compared with sensibles, then making them dependent upon some first principles simpy raises the problem anew for those first principles. Consequently, introducing the first principles is either unnecessary or worthless. Finally, Speusippus accepted the same (or very nearly the same) principles; yet why should he accept them, if he did not even believe in forms and so had no need to solve such a problem with them? I have to believe that Sayre's account of Plato's purpose in adopting these principles is not correct.

The Tubingen school has maintained that these unwritten doctrines not only were asserted by Plato, but also underlie all of his dialogues and represent his true views. They point out--justly, I think--that the evidence for these views is just as good as the evidence for what philosophers like Democritus said (namely, testimony from others).33 However, there are two corrections that must be made to their position. First of all, there is no good reason to believe that these doctrines represent Plato's true views while what we find in the dialogues represent his popular views. I believe that the Tubingen school itself has come to recognize this,34 but in any case, it is a view that is not supported by anything in Aristotle, for Aristotle had no qualms about referring to material in the dialogues.35

Secondly, there is no reason to believe that the very views that we can extract from Aristotle underlie all of the dialogues. In the middle dialogues and earlier it is true that there is some suggestion that Plato's thought went somewhat beyond what was said in the dialogues. However, the most definite suggestion to that effect is at Republic 506dff. and 509c in connection with the form of the Good, where it appears that that form is the one fundamental principle. That there is just one principle is suggested by the words "the principle of all" at Republic 511b7. Yet the information we receive from Aristotle and others indicates something different. They talk of not one principle but of two, and neither one of these two principles is defined as the good (although one of them, the One, may ultimately be identified with it). In other words, there is a change between what we hear in the Republic and what we hear from the ancients; the obvious way of explaining this is to say that, regarding the fundamental principles, Plato changed his mind between the middle and late periods. Most of what we hear from the ancients will have been from the late period (for the simple reason that most of what we hear is from Aristotle, and Aristotle had not entered the Academy until the late period). In addition, as one of the Tubingen scholars himself admits, the dialogues that seem closest to what Plato was talking about in the unwritten doctrines were from the late period, the Parmenides, Sophist and Philebus.36

Finally, at Metaphysics 1078b9-12 Aristotle talked about two different stages in Plato's theory ("Now, regarding the forms, we must first examine the theory of forms itself, not connecting it in any way with the nature of numbers, but treating it in the form in which it was originally understood by those who first maintained the existence of the forms"). The first stage is simply the middle-period theory of forms with which we are all familiar. The second stage involved connecting the forms with the nature of numbers. It seems reasonable to suppose, since the first stage is nothing other than the middle-period theory of forms, that Aristotle's description of the second stage includes all of the unwritten doctrines (even though strictly speaking it really relates to only one of those doctrines, and a very dubious one at that) and that Plato engaged in theorizing about the fundamental principles in his late period only.

To conclude this section, it likely is the case that Plato believed in two fundamental principles and that he derived the rest of reality (including the forms) from them. It is likely because others besides Aristotle supposed the same things and because Aristotle imputed nearly the same two principles to Speusippus, although it seems highly absurd to do this to him.

VIII. Plato's Answer to Speusippus

So far I have suggested that Plato failed to answer the Third Man to Speusippus' satisfaction. Accordingly, it was incumbent upon Plato to answer Speusippus in some other way. Since it turns out that the best place to find a Platonic answer to Speusippus is not in the dialogues but in the unwritten doctrines, we must perforce look at the unwritten doctrines. We there find that the way Plato chose to answer Speusippus entailed extending his theory by adding two fundamental principles, which he called the One and the Indefinite Dyad. These two principles represent unity and diversity, and Plato probably felt that everything could be explained by appealing to them. Apparently, Speusippus agreed, for he adopted two similar principles (the One and the Plurality). Plato insisted that the rest of his own system could be derived from his two principles, but he probably also felt that Speusippus could not derive the Speusippean system so easily from Speusippean principles. Certainly, both Aristotle (Metaphysics 1090b20) and Theophrastus (Metaphysics 6a15-b17) agreed that Speusippus did not construct his system very coherently. (Naturally, the details of these derivations given by Plato and Speusippus are lost to us.) Why Plato chose this way to attack Speusippus should be clear, for it did double duty. Introducing two principles could be used to show that Speusippus' system was clumsily constructed and to show that forms exist (for the existence of forms could be derived, so Plato maintained, from those principles).

To recapitulate, Speusippus scored a point against Plato since Plato could not effectively answer the Third Man. But Plato scored a point against Speusippus since Plato's system, but not Speusippus', could be cogently derived from the most basic principles of reality.

How do I know that Plato extended his system for the purpose of scoring a point against Speusippus? First of all, this is the way that Theophrastus treated the systems of Plato, Speusippus, and others, that these systems could be judged to see which could explain all of reality in the best possible way with the most intelligently constructed and coherently argued system. Speusippus was not considered the winner.

But secondly, saying that Plato answered Speusippus in the unwritten doctrines makes sense of a great deal of other evidence. It helps fill out my explanation of the Aristotelian evidential paradox I mentioned earlier. That paradox states that Aristotle treated the Third Man as obviously valid against the theory of forms, while never declaring that Plato made any revisions in this theory. If we treat Aristotle charitably, which many fail to do, then the only way I know of to escape from this paradox is to say that Plato had temporarily conceded that he had no answer to the Third Man; he merely held out the hope that some day he would have an answer. But it is reasonable to believe that under those circumstances Plato would have felt compelled to argue against Speusippus somehow and that he did so by attacking Speusippus' whole system, showing that it was an abysmal failure. An attack of this sort on Speusippus can be easily read into the unwritten doctrines.

IX. Why Plato Left These Doctrines Unwritten

In two passages Plato gave a hint as to why he left these doctrines unwritten. One of these appears in the Phaedrus at 275d-e, where Plato indicated that when something is written down, it becomes impossible to ask questions of it. This may be reflective of the early part of the late period when the situation between Plato and Speusippus was in flux, with Speusippus advancing the Third Man, Plato advancing reasons why it is not valid, Speusippus countering those reasons, and so on. In other words, Plato felt that there was no point in writing down something that may need to be clarified or even retracted later on.

The second hint comes from the Seventh Letter at 341c, where Plato said that "acquaintance with [these principles] must come rather after a long period of attendance on instruction in the subject itself and of close companionship."37 Accordingly, we ought not to expect that these principles would appear in print. Moreover, it is not atypical of Plato to have done this. At Republic 506d and 507a he indicated that he could not give a full account of the form of the Good, which apparently was the only fundamental principle he accepted at that time. His reluctance in both instances may have been due to the abstract nature of the topic and to the fact that it is difficult to prove any such principles to be true.

X. The Timaeus, Philosopher, and Laws

I maintain that my view of the late period lets us solve some Platonic mysteries. Let me begin with the Timaeus. Those who believe the Timaeus to be a middle dialogue will be unpersuaded by what I say here. Whether one holds it to be middle or late, however, its appearance raises a problem that has best been described by Gilbert Ryle:

"After Socrates' renunciation of physical speculations in the Phaedo and after his contemptuous treatment of observational astronomy in the Republic VII and of medical science in the Republic III 405-410 it is matter for surprise that Plato now produces a full-scale treatise On Nature and the Composition of Man."38

In other words, it is a problem to explain why Plato turned to the study of science after developing theoretical reasons for shunning it earlier. My theory of the late period explains this curious behavior on Plato's part, for it is of a piece with his extension of the theory of forms in the direction of the most general principles of reality. That is, in order to promote his system as a viable alternative to Speusippus' system, he needed either to answer the Third Man or, failing that, to show that Speusippus' system was inferior to his own. Cherniss has suggested that the Timaeus contained an answer to the Third Man at 31a, as I mentioned earlier. Nevertheless, by this time Plato had probably had a sufficient number of arguments with Speusippus and others to know that there was no guarantee that this answer (which had already appeared at Republic 597c) would be thought satisfactory. So, he decided to play it safe by also showing that Speusippus' system was inferior to his own. One way to do this was to show that in the realm of the senses a plausible account based on his theory of forms could be constructed. Consequently, he was able to conquer his earlier reluctance to engage in such a task, for it was necessitated by the exigencies of his debate with Speusippus.

Recall that I already suggested that Plato's failure to complete this trilogy was due to a problem perceived in the Timaeus by Plato's contemporaries. One such problem is with the answer to the Third Man at 31a that has been suggested by Cherniss. I indicated earlier that this was not much of an answer. If this answer was deemed unsatisfactory by Speusippus, then Plato will have felt that the rest of the project was not worth finishing.

As for the absence of the Philosopher, it is significant that on Brandwood's chronology, the order of the dialogues in this period of Plato's life are Sophist, Politicus, and Philebus, with the Philosopher (had it been written) appearing in between the second and third of these. All three of these dialogues use the method of collection and division, except that Philebus 14c-18d discusses it as though it (and the theory of forms) had come under severe attack. Indeed, Cherniss suggested that Speusippus' (only) reason for rejecting the forms was that he had constructed a dilemma for Plato: either the forms exist or the method of division is valid, but not both.39 Since both the Sophist and the Politicus use that method with no qualms, and since the Philebus contains a long and complicated discussion of it, it stands to reason that Speusippus' dilemma was formulated after (or during) the writing of the Politicus but before the writing of the Philebus.

But we can also conjecture that this dilemma prevented Plato from writing the Philosopher, for that dialogue was going to use the method of division to nail down once and for all what a philosopher is (namely, someone who pursued the knowledge of the forms). Once the method came under attack, that project was put on hold until this difficulty was dealt with. Plato decided to float a preliminary answer in the Philebus, and if this answer proved convincing, then the Philosopher would be taken up again. But the answer in the Philebus was wholly inadequate. Plato there said (without proving) that the method comes from the gods and has been the method that has resulted in every discovery in the sphere of the arts and sciences that has been brought to light (16c), and that in addition its correct use represents the difference between a contentious discussion and a philosophical one (17a). Speusippus was understandably not convinced by these unproven assertions, and Plato never got around to finishing his trilogy; instead, he turned to something he deemed more important, political philosophy (in the Laws).

Finally, in regard to the Laws, neither the unitarians nor the revisionists can provide satisfactory explanations for Plato's turn to the second-best system in this dialogue from that of the philosopher king that was described in the Republic. First of all, with respect to revisionist theory, either Plato perceived that his revision of the theory of forms had no effect on political philosophy, or he perceived that it did have an effect. If the former, then this change cannot by explained by the revisionists. But if the latter, then the sort of change we would expect is one in which the best system was revised; instead, we find that Plato kept the best system as an ideal but felt it necessary to describe a second-best system, which could be more easily realized. That sort of change is more indicative of some sort of disappointment in the real world than a change of mind in metaphysics. Either way, the true explanation of what happened lies outside of the revisionists' theory.

As for the unitarians, they typically do talk about a disappointment in the real world, namely Plato's failures in Sicily to turn the ruler there into a philosopher king. However, they neglect the fact that Plato felt a philosopher king could be produced in not just one but two ways, and this failure relates to only one of these ways. If Plato could not turn a king into a philosopher, then he could try turning a philosopher into a king. We know that Plato did have ambitions along these lines, for we know that people in the Academy sometimes engaged in political missions of one sort or another.40 It is not unreasonable to believe that Plato hoped that one day some polis would accept one of his students as a philosopher king. If Plato had thought that this other way of creating philosopher kings was still viable, why would he have bothered with the Laws? Since Plato did bother with the Laws, that suggests that this second way of creating a philosopher king was a failure as well. But while this failure could be due to many causes, in light of Parmenides 135a3-7 the obvious suggestion is that most of his students no longer satisfied one of the requirements for being a philosopher king, namely the belief in the forms. Whence the statement at Laws 875d that Plato was forced to accept the second-best system of "ordinance and law" because "the understanding of the forms is too dim in people's minds." Surely this reference is not just to some rulers in Sicily, but also to his own students.

XI. Conclusion

In his writings, Aristotle stated or implied certain claims about Plato. On the one hand, he implied that Plato had no satisfactory answer to Third Man argument. On the other hand, he implied that Plato never revised his theory. Reconciling these two claims has always been difficult. If Plato had no satisfactory answer to the Third Man, then he must have realized it was valid, and so he ought to have revised his theory. But Aristotle never told us that he revised his theory, so apparently he did not do so. But then he must not have thought the Third Man was valid and so must have had a satisfactory answer to it. Since Aristotle did not give this answer, we are back where we started; we are back to thinking that Plato did not have a satisfactory answer to the Third Man. The unitarians and revisionists have broken out of this circle by denying one of the claims that can be extracted from Aristotle. The unitarians insist that Plato had a satisfactory answer to the Third Man, which Aristotle failed to record. The revisionists insist that Plato revised his theory, and that Aristotle happened not to mention this. However, there is no need to deny either of Aristotle's claims. As my theory shows, it is entirely possible that both claims are true. In addition, my theory explains how the unwritten doctrines turn out to be an important part of the late period.

To explain again how I believe that all of these claims can be combined in a plausible theory, let me restate what I think happened to Plato in connection with the Third Man argument. In hismiddle period, Plato founded the Academy and developed the theory of forms, applying it to other branches of philosophy. He was extremely confident that it was correct; this is evident from remarks at Republic 476c that those who do not accept the forms are dreaming and from his apparently being unaware of any intelligently constructed arguments against his position. At some point someone invented the Third Man argument. When Plato reproduced this argument in the Parmenides, he indicated three points. At 135a-b, Plato indicated that he thought the argument was invalid, although he acknowledged that it was difficult to show this. At 135b-c, he indicated that in any case it would be impossible to give up the theory of forms because it was necessary for thought and discourse. Most important, and most overlooked by modern scholars, is that at 135a3-7 he acknowledged that most people thought the argument sufficiently persuasive that they abandoned the theory of forms. Based on other information we already have, the most important person among those abandoning the theory of forms was likely to have been Speusippus.

As part of an ongoing debate with Speusippus, Plato used a two-pronged approach: he gave an answer to the Third Man, and he launched an ad hominem attack against Speusippus. The answer to the Third Man appeared at Timaeus 31a, but there is no likelihood that Speusippus found it convincing; consequently, Plato abandoned the rest of that trilogy. For in the rest of that trilogy he planned to recount the mythical exploits of philosopher kings in ancient Athens, but given that philosopher kings must believe in forms, and given that Plato's best students no longer believed in forms, telling this myth was deemed a worthless task.

At this point, Plato probably adopted that rhetorical answer to the Third Man he used for the rest of his life:

"I know that I have nothing important to say against this argument at this time, but I am utterly convinced of the existence of forms, for positing their existence solves too many deep philosophical problems and is anyway necessary for the possibility of thought and language to even think of abandoning them. I am confident that some day I or someone else will find an answer to this vexing Third Man argument, after which no one of any intelligence could doubt the existence of such important and divine entities as Justice, Beauty, Good, and the like."

The second prong of his approach to Speusippus' challenge involved an ad hominem attack. By extending his theory, Plato could show to others that his own theory was more coherently reasoned and cogently constructed than Speusippus' system was. This extension went in two directions: to the more specific and the more general. The former is represented by the cosmology of the Timaeus, for Plato felt himself forced to show that he could account for natural phenomena as well as anyone. The latter is represented by the two principles spoken of in the unwritten doctrines, the One and the Indefinite Dyad (representing unity and diversity), which he felt were sufficiently plausible that no one could deny them and which he felt entailed his own system. In fact, Speusippus did apparently find these two principles plausible enough that one of them he adopted outright (the One) and the other he modified slightly (choosing Plurality rather than the Dyad), but it was to no avail. Concerning the task of deriving one's system from one's fundamental principles, the ancients seemed to agree that Plato did a better job than Speusippus did. That was a point in Plato's favor. On the other hand, the Third Man was a point in Speusippus' favor.

Meanwhile, Plato was still producing dialogues. After abandoning the Timaeus trilogy, he turned to the Sophist trilogy, which used the method of division. (The Sophist is not directly related to Plato's crisis with the Third Man, but it is indirectly related, and I hope to explain this someday. The details are too lengthy to delve into on this occasion.) The third dialogue of this trilogy was intended to use the method of division to flesh out the nature of the philosopher (who naturally would turn out to be a person who believed in forms). However, this trilogy had to be abandoned as well, for it was after writing the Politicus that Speusippus sponsored a second criticism in the form of a dilemma that forced Plato to choose between the forms and his new method of division. Plato floated a weak answer to this in the Philebus, but Speusippus was unconvinced. The third dialogue in the Sophist trilogy, a dialogue meant to show that philosophers believe in forms, had to be put on the shelf until this and other objections were answered. Meanwhile, Plato felt that it would be more worthwhile to give the rest of the human race a second-best political philosophy (given that his ideal system would not be realized for want of people who believed in the forms) than to give an answer to some obscure problem in metaphysics. If and when that project was completed, he could always turn back to the Third Man and the other objections and search for an answer to them once more. Accordingly, Plato turned to writing the Laws, but he apparently never finished it (for the manuscript was not put into its final form, according to Diogenes Laertius, III.37). In any case, he died never having found any answer to the Third Man.

Plato and Speusippus emerged from these debates in a standoff, with each of them gaining a point against the other. Speusippus could say against Plato that he had not answered the Third Man, and Plato could say against Speusippus that his system was not easily derivable from the most fundamental principles. Of course, this standoff was broken by Aristotle, who propounded a metaphysical system different from either of them and with whom it is appropriate to end this article. In fact, this article could have been entitled something like "The Vindication of Aristotle Concerning His Testimony on Plato," for it has turned out that one can interpret Aristotle's remarks on Plato much better than many have wished to think. Some might argue that in being charitable to Aristotle I have been uncharitable to Plato, for I have portrayed him as continuing to maintain a theory which had an objection leveled against it which he could not satisfactorily answer. But this seems like ordinary human behavior to me. As Thomas Kuhn has explained, for every scientific theory (and presumably for metaphysical theories as well), there are phenomena that the theory cannot explain. Most of those believing the theory think that what is explained by the theory is so important that the phenomena that are not yet explained by it do not deserve to count against it. Eventually, those who investigate such phenomena, if they repeatedly fail to explain it in terms of the theory in question, decide that these unsolved puzzles ought to count against the theory. It was the same with Plato and the Third Man. The theory of forms was such a solid and important achievement in his mind that he would never give it up for the sake of some trifling logical puzzle that he could not answer yet. His opponents, being less charmed by the theory of forms, thought the Third Man a very serious objection indeed. There is nothing in any of this that indicates a lack of charity to Plato on my part. And so I conclude by saying that Aristotle was right that Plato accepted these unwritten doctrines, right that Plato never revised his theory of forms, and right to think that Plato had no answer to the Third Man argument.41

John Pepple
Affiliated Scholar in Classics and Philosophy
Kenyon College

XII. Notes

1. See W.D. Ross, Plato's Theory of Ideas, Oxford: Clarendon Press, 1951, pp. 151-2 for a discussion of this topic.

2. Parmenides 131e-132b. This argument has been discussed endlessly ever since the publication of Gregory Vlastos's article examining its logic, "The Third Man Argument in the Parmenides," Philosophical Review 63 (1954), 319-349. While many of these discussions involved debates concerning the precise formulation of its premises, here is a conservative set of premises that treats Plato as charitably as possible:

One Over Many premise (OM): If a number of entities are all F, there must be an F-ness by virtue of which they are all F.

Self Predication premise (SP): All F-nesses are F.

Nonidentity premise (NI): If x is F, then x is not identical with the F-nesses by virtue of which it is F.

These are from Wilfred Sellars, "Vlastos and 'The Third Man,'" Philosophical Review 64 (1955), 417-418. The argument begins with a set of things that have the feature F. By OM, there is a form F-ness by virtue of which these things are all F. By SP, this form is itself F. By NI, this form cannot be identical with the form or forms in virtue of which it is F. Hence, there must be another form of F-ness by virtue of which the first form is F; and still another form by virtue of which the second form is F; and so on.

3. Obviously, this depends upon what I take to be the late period. I have adopted the chronology set forth by Leonard Brandwood in A Word Index to Plato, Leeds: W.S. Maney & Son, 1976, pp. xvi-xviii. He gives the following order to the dialogues I am interested in: Phaedo, Republic, Parmenides, Theaetetus, Phaedrus, Timaeus, Critias, Sophist, Politicus, Philebus, and Laws. I take the late period to begin with the Parmenides and the Theaetetus, which some take to be at the end of the middle period. That is just a terminological point. More important is that some have denied that the chronology can be determined on the basis of style, as Brandwood and others contend. I will discuss that topic below.

4. There are two articles representing the first two of these three theories, which can be found in R.E. Allen's Studies in Plato's Metaphysics, London: Routledge & Kegan Paul, Ltd., 1965. Harold Cherniss, "The Relation of the Timaeus to Plato's Later Dialogues," pp. 339-378, argued for unitarianism, while G.E.L. Owen, "The Place of the Timaeus in Plato's Dialogues," pp. 313-338, argued for revisionism. As for the skeptics, they are represented by Holger Thesleff, "Platonic Chronology," Phronesis 34 (1989), 1-26, and Studies in Platonic Chronology, Commentationes Humanarum Litterarum 70 (Helsinki: Societas Scientiarum Fennica, 1982); Jacob Howland, "Re-Reading Plato: The Problem of the Platonic Chronology," Phoenix 45 (1991), 189-214; and Debra Nails, Agora, Academy, and the Conduct of Philosophy, Kluwer, 1995.

5. Thesleff, Studies in Platonic Chronology, pp. 54ff. and 162ff.

6. Thesleff, Studies in Platonic Chronology, p. 23.

7. Thesleff, Studies in Platonic Chronology, p. 105.

8. Debra Nails, Agora, Academy, and the Conduct of Philosophy, p. 22.

9. Thesleff, "Platonic Chronology," p. 4.

10. Marjorie Grene, Descartes: Philosophers in Context, Minneapolis: University of Minnesota Press, 1985, p. 186.

11. See the letter from Descartes to Colvius of November 14, 1640:

"I am obliged to you for drawing my attention to the passage of St. Augustine relevant to my I think, therefore I am. I went today to the library of this town to read it, and I do indeed find that he does use it to prove the certainty of our existence." (AT, iii, p. 247.)

12. See, for example, W.K.C. Guthrie, A History of Greek Philosophy V, Cambridge University Press, 1978, p. 34, who suggests 370-367 as the date of the Parmenides. Aristotle is commonly thought to have entered the Academy in about 367 at the age of seventeen.

13. There are several indications that Plato planned to reveal the nature of the philosopher in a third dialogue. At the beginning of both the Sophist and the Politicus, it is suggested that there will be a discussion in which three sorts of people will be defined: sophists, statesmen, and philosophers. The Sophist defines the sophist, and the Politicus defines the statesman, leaving us to believe that a third dialogue was planned in which the philosopher would be defined. At Politicus 257b, Theodorus asks the Stranger "to define the statesman or the philosopher, whichever you prefer to seek." The implication is that the Stranger will take up the alternative not chosen in a third dialogue.

14.Cornford, Plato and Parmenides, London: Routledge & Kegan Paul, 1939, p. 95.

15. Cornford, Plato and Parmenides, p. 87, Richard Patterson, Image and Reality in Plato's Metaphysics, Indianapolis: Hackett, 1985, p. 51, and Richard Robinson, Plato's Earlier Dialectic, 2nd ed., Oxford University Press, 1953, p. 265.

16. Richard Robinson, Plato's Earlier Dialectic, p. 265, Karl Popper, The Open Society and Its Enemies, rev. ed., Princeton University Press, 1966, p. 134, and Harold Cherniss, The Riddle of the Early Academy, Berkeley, 1945, p. 70.

17. Cherniss, Aristotle's Criticism of Plato and the Academy I, Baltimore: Johns Hopkins Press, 1944, pp. 293ff.

18. Cherniss, The Riddle of the Early Academy, p. 40. Cf. Aristotle, Metaphysics 1039a24ff.

19. Cherniss, The Riddle of the Early Academy, p. 70.

20. Owen, "The Place of the Timaeus in Plato's Dialogues," p. 230.

21. R.M. Dancy, "Ancient Non-Beings: Speusippus and Others," Ancient Philosophy 9 (1989), pp. 221ff., especially 226.

22. W.D. Ross, Plato's Theory of Ideas, p. 218.

23. Cherniss, The Riddle of the Early Academy, p. 52. See also Leonardo Taran, Speusippus of Athens, Leiden: E.J. Brill, 1981, p. 39. Although he is concerned with Speusippus rather than with Plato, the argument is the same.

24. Cherniss, The Riddle of the Early Academy, pp. 16-17, 29, 58-59, and 72.

25. For example, Ross, Plato's Theory of Ideas, chapters 9-16, and J.N. Findlay, Plato: The Written and Unwritten Doctrines, London: Routledge & Kegan Paul, 1974, pp. 455-473.

26. Simplicius, In Phys. p. 151, 6-11 and p. 453, 25-31.

27. Metaphysics 1028b21-24, 1087b6-9, and 1087b27.

28. See Cherniss, The Riddle of the Early Academy, pp. 51ff.

29. Of course, Taran, Speusippus of Athens, pp. 32ff., following Cherniss's lead in treating Aristotle uncharitably, does wish to say that the One and the Plurality are not fundamental principles of Speusippus. However, he has been widely criticized. See John Dillon, "Speusippus in Iamblichus," Phronesis 29 (1984), p. 328, Ian Mueller, "On Some Academic Theories of Mathematical Objects," Journal of Hellenic Studies 106 (1986), p. 117 and n. 23, and Dancy, "Ancient Non-Beings," pp. 215ff.

30. Vlastos, "On Plato's Oral Doctrine," in Vlastos, Platonic Studies, Princeton University Press, 1981, pp. 397-398.

31. Kenneth Sayre, Plato's Late Ontology, Princeton University Press, 1983. See p. 184 for remarks on the abandonment of separation.

32. See Mohan Matthen in his review of Sayre's book in The Philosophical Review 94 (1985), pp. 395-396.

33. Hans Joachim Kramer, Plato and the Foundations of Metaphysics, ed. and trans. by John R. Catan, Albany: SUNY Press, 1990, p. 282, n. 20.

34. Kramer, Plato and the Foundations of Metaphysics, p. 58.

35. On this point, see Richard Kraut, "Introduction to the Study of Plato," The Cambridge Companion to Plato, ed. Kraut, Cambridge University Press, 1992, pp. 22-23.

36. See Kramer, Plato and the Foundations of Metaphysics, p. 157.

37. See Konrad Gaiser, "Plato's Enigmatic Lecture On the Good," Phronesis 25 (1980), pp. 18-19 for reasons why the Seventh Letter is genuine and p. 14 for why we should consider this sentence to be about the first principle.

38. Gilbert Ryle, Plato's Progress, Cambridge University Press, 1965, p. 12.

39. Cherniss, The Riddle of the Early Academy, pp. 39ff.

40. See, for example, Plutarch, Adv. Colot. 1126c, and Diogenes Laertius, III.23.

41. The ideas expressed in this article were first presented at the Minnesota Ancient Greek Philosophy Conference on November 6, 1993. I thank the commentator Del Reed for his remarks on that occasion. It was also presented at a meeting of the Ohio Philosophical Association on April 8, 1995. While many people (such as Sandra Peterson, Vicki Harper, Norman Dahl, and Gregory Vlastos) have helped me formulate my views on Greek philosophy, I have to thank several people who endured my long letters to them on the topic of this article and responded with encouragement: Leonard Brandwood, William J. Prior, Rosamond Kent Sprague, and Richard Kraut. Naturally, any mistakes herein are my own.

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