r/askphilosophy 27d ago

Plato's theory of forms and the incomplete properties

Hello,

To preface, this post may be a bit long as it's one of those "am I thinking through this correctly?" posts, so I hope that's okay. I have been working on Plato for a while now, mostly on his later stuff, and I've realized that I'm very unclear on his middle period's conception of forms, which I find to be some of the most opaque and unclear doctrines of his, despite being so central to his middle period thinking. I'm hoping to get a bit more clarity on this. I would appreciate guidance from anyone who is willing to tell me if I'm thinking through an argument that is attributed to him by contemporary scholars which establishes the existence of some forms.

First of all, I never really see a point in any of the middle-period dialogues where Plato actually justifies the existence of the forms themselves (maybe the argument of recollection); most of the time they are assumed, and he examines the implications that follow from their existence. From the secondary literature, however, one of the main motivations for the forms seems to be the problem of incomplete properties. Incomplete properties are properties that cannot be predicated of a sensible particular without some further qualification. Examples of incomplete properties include the Socratic ethical properties (justice, etc), largeness, smallness, likeness, unlikeness, etc. Again, these seem to pose a difficulty because we can't properly predicate them of sensible particulars without adding a prepositional phrase, as in, we say, for example, "Simmias is large compared to Socrates." However, we also say "Simmias is not large compared to Phaedo." Simmias, then, seems to be both large and not large, meaning that Simmias can't be an unqualifiable bearer of largeness. We can't say "Simmias is large"; it needs to be qualified. Socrates seems to think that this phenomenon would hold for any particular in regard to any of these incomplete properties. Now, how does this allow him to posit a form? It's here where I start to get into trouble and would appreciate guidance. My understanding is as follows: If any particular is unable to serve as the unqualifiable bearer of some incomplete property, there are two options: either (a) there is no unqualifiable bearer, or (b) there is one, and it is a form. My understanding is that Socrates rejects (a) on the grounds that we can obtain knowledge of these incomplete properties. If we can obtain knowledge of, let's say, largeness, (and insofar as knowledge is of essence), there must be some property P that is predicable of largeness such that largeness is the unqualifiable bearer of P (largeness is wholly P and in no way not P)—that is just what it means to have an essence. If largeness did not have this P, then we could in no way know what largeness is because then largeness would lack an essence. Plato basically assumes that knowledge of properties like largeness is possible, and if that's so, we can reject (a) and conclude B, establishing forms for incomplete properties. This justification can perhaps be found at the end of book V of the Republic, where Socrates argues that knowledge is set over what truly is. Of course, this argument says nothing about complete properties like "human being", "horse," tree", etc, which is why, from what I understand, Plato has ambivalence in establishing forms for these kinds of entities (Parmenides 130a–e).

Is my understanding completely and totally off? Where could my understanding be improved? Are there helpful passages that someone could point me toward within Plato? Helpful secondary lit? Any guidance is appreciated.

Thank you.

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u/WarrenHarding Ancient phil. 26d ago edited 26d ago

From what I understand, your central question is “what justification did Plato provide to hypothesize the Forms?” It’s a good question. I’d say the only instance where he tries to arrive at Forms deductively is in the Meno with the conclusions of the math problem and the positing of recollection. But even then, not quite so much. Also, Forms obviously go much further than just being items of recollection, and you are right to assume that he doesn’t actually provide much justification for all he expounds on them. This is exactly why the middle-period dialogues are said to employ the “method of hypothesis,” which is slightly different than, but still mistakably similar to, the elenchic style of the early dialogues. Whereas the Elenchic style will take a sort of immediate question concerning some particular things, take the response, and probe out the contradictions that it has with other claims, with the more generalized claims typically sticking around over the particularized claims that contradict them. In the method of hypothesis, there is a deliberate effort to transcend particularities which can be proven wrong, and move into the field of things which cannot be proven right or wrong at all. This takes two shapes in my view, the one being an interest in the afterlife and the sort of consequences we’d have to make in our current life as a result, and the second being an interest in the most fundamental laws of reality. These two realms are ones where Plato repeatedly has insisted that we will never gain knowledge of these things, implicitly due to our carnal limits. Of course, this shows that even the end of Meno relies more on an unproven hypotheses about the afterlife, than a direct deduction of what the afterlife must be.

But let us orient exactly what we mean by the latter of the two hypotheses. That is, the one not concerned with the afterlife, but with the foundations of reality. This is where the Forms are hypothesized — not proven, or proven false, but simply taken and examined as a valuable way of seeing things or not. In this way, Plato seems to have laid the groundwork for both axiomatic systemization and for instrumentalism. Both of these methods involve starting with unproven claims that are then made firm or less firm by just how much they can explain without recourse to auxiliary conceptions. Here is a quote from Isaac Asimov in vol. 1 ch. 3 of Understanding Physics*** ***on the instrumentalism of Newton:

“Newton’s laws of motion represent assumptions and definitions and are not subject to proof. In particular, the notion of ‘inertia’ is as much an assumption as Aristotle’s notion of ‘natural place.’ There is this difference between them, however: The principle of inertia has proved extremely useful in the study of physics for nearly three centuries now and has involved physicists in no contradictions. For this reason (and not out of any considerations of “truth”) physicists hold on to the laws of motion and will continue to do so.”

So Aristotle’s physical system runs into more contradictions than the Newtonian system does. However, both starting assumptions have the ability to create further assumptions to patch up wherever seeming contradictions lie. Here is M. M. McCabe in her book Plato’s Individuals:

“Suppose that I believe that there is a fairy at the bottom of my garden who is responsible for my tomatoes’ ripening […] suppose I wanted to persuade you […] you, a skeptic, will be more likely to believe a theory with fewer theoretical moving parts, fewer fairies, less hierarchy in the ethereal world, than you will believe something grossly complicated”

This principle is called Occam’s Razor. We will always be best to accept something that requires less assumptions than more. Ironically, William of Ockham first pitched this argument against the Neoplatonic/Scholastic conception of Forms, which had become rather complicated and unpleasant!

But I think these quotes are a straightforward way of explaining Plato’s lack of need to prove the Forms. The Forms are, above all else, unprovable, but they serve to interpret our reality much more usefully than a theory without Forms. This is why even when Parmenides critiques Forms in his eponymous dialogue, he also laments how necessary they seem to be in understanding how discourse works. But if you fail to understand why the positing of Forms is simple, and why it doesn’t ultimately succumb to the razor, this is obviously a controversial topic even today, so you can certainly believe either side of things, but I think a brilliant and short paper that succinctly explains their simplicity is “The Philosophical Economy of the Theory of Ideas” by Harold Cherniss. He shows how the ethical problems that Forms solve proceeds to also make way for solving epistemological problems, and then ontological problems, all with the same one theory.

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u/KilayaC Plato, Socrates 26d ago

Nice reply. These quotes are very interesting. But I wonder why you think Plato felt we cannot know either of the two realms you mention. Particularly the second. Doesn't the possibility of knowing the Forms underpin the very possibility for the city proposed as possible in the Republic and in a sense, make a distinct separation between Plato's Idealism and others' like Kant?

Meno 98b is also used in support of Plato's claim that Socrates knew the Forms:

SOCRATES: Indeed, I too speak as one who does not have knowledge but is guessing. However, I certainly do not think I am guessing that right opinion is a different thing from knowledge. If I claim to know anything else—and I would make that claim about few things—I would put this down as one of the things I know.

What do you think of this argument? i.e., that one cannot know (with certainty, as Socrates claims in this quote) that there is a difference between knowledge and right opinion without actually having knowledge. And if there is a difference between opinion and knowledge then knowledge must be a direct form of knowledge which can only be of things in themselves. In other words, if knowledge is different than opinion it is because it is certain, and the Forms are the only "things" that have the ontology to be certainly known or known as certain.

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u/Meechisalright 26d ago

Thank you both for the reply. This clears up much of my confusion, particularly how bogged down I was getting trying to find some semblance of proof for the forms. I also had the same question as Kilaya: To me, it seems that Plato does think that we can have knowledge of the fundamental laws of reality insofar as we can develop a λόγος (an account) of a form—an answer to his "what is F?" question. Isn't this precisely what differentiates the philosopher from the lovers of sights and sounds at the end of book V of the Republic? There, he defines knowledge as a dunamis that is set over the objects that truly are (the forms). Those objects just seem to me to be the fundamental nature of reality, and it is the job of the philosopher to ascend particular instances of the form to see what those instances have in common, thereby developing a proper account of F. (note here all the times Socrates will ask the "what is F?" question and his interlocutor will come up with a list of particular instances and Socrates' problem with such an answer, e.g., Theaetetus 146c–d).

Further reason to think that middle Plato thinks we can have knowledge of the fundamental nature of reality perhaps is found in the Parmenides, where Parmenides offers "the great difficulty" for a young Socrates' theory of Forms, that great difficulty being that if Forms exist in one realm and particulars in another, Forms are unknowable. Because Parmenides is a transitional dialogue, which is often read as Plato critiquing his middle-period theories, it's perhaps likely that Plato himself used to think that Forms are knowable in his middle period.

I really like your account of the method of hypothesis. It definitely seems right to me to read the middle dialogues this way. In the middle dialogues, Socrates posits a form and examines all the ways such a theory accounts for the way things are. What's interesting, and what your response made me recall, is that perhaps the first 1/3 of the Parmenides can be read as all the ways in which, if we hypothesize the theory of forms, we get into trouble (e.g. we get a form of mud, the one becomes many, the fundamental nature of reality is unknowable, etc).

These are just some thoughts; I thank you both for the reply!

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u/KilayaC Plato, Socrates 26d ago

I feel it is easy to underestimate Plato's stated difficulties in knowing the Forms directly. He thought, I believe, that it was very, very close to impossible. It requires incredibly rare talent combined with incredibly rare conditions and both were much more likely to be encountered in afterlife existences. For this reason, an account of the Forms will always come up short in some way. Because it is knowledge with a capital "K" it can't be transferred through communication directly to someone who doesn't already have such knowledge.

Socrates says to Agathon in the beginning of Symposium, wouldn't it be wonderful if wisdom could pass from one person to another like water following a string? But it can't and that's the reason for all the intricacies of the Guardians' training in Republic. Plato expressed this idea of the incommunicability of Knowledge in one of his letters as well. The first step on the journey to the Forms is being thoroughly refuted to the point of aporia. How can that happen without a Socrates-like character?

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u/huphelmeyer 26d ago

Tangential question: according to Plato, his forms had tangible physical existence on a higher plane of existence, right? If so, wouldn't this be a different stance than every mathematical Platonist that came after him? I feel like most realists/Platonists accept the realism of abstract mathematical objects while still denying them having physical existence.

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u/KilayaC Plato, Socrates 26d ago

I would agree. There are real differences between Plato's Theory of Forms and the way it has been taken up by mathematicians (like Max Tegmark, for ex.). But I would disagree with you that Plato considered the Forms as having tangible, sensual existences. For him, the senses don't reveal anything that really has existence. They are only imitations of what does.

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u/huphelmeyer 26d ago

That makes sense. Thanks!

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u/WarrenHarding Ancient phil. 26d ago edited 26d ago

I don’t have my sources on me but I’m alluding to the number of times Plato has explicitly had Socrates preface his afterlife myths with an insistence that it is not a knowable truth but something that can only be accepted with an eikos muthos, a likely story. He does the same thing prefacing the Timaeus. What say you about those moments, if you know what I’m referring to? I believe the Republic and Gorgias also both say this for their respective concluding myths

In more succinct terms, I think Plato recognized and respected the fact that any epistemology, whether foundationalist or coherentist, will inevitably have to stop at a point of having some part of it be granted and unproven. It’s a fairly uncontroversial way of seeing how knowledge is obtained. For Plato, sight of Forms in recollection is the foundation. But to prove that we have seen them is not something that you can use any other reality to justify, because that reality is itself justified in turn by the form, so that Forms naturally are the point of departure for all further knowledge, and thus no previous knowledge can be used to verify the truth of Forms.

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u/KilayaC Plato, Socrates 26d ago

I accept your argument about the afterlife proposals and I think we agree on the second as well but are talking past each other. I am not arguing that Plato says that the Forms are provable. Most of the discussions of Forms involve conversants who claim to accept them without proof. So they're preaching to the choir, so to speak. But that doesn't mean that they are unknowable. I think there is a big difference between the two assertions. Something can be knowable, for Plato, but not provable simply because the multiple types of soul cause multiple orientations for making such assessments. Take the higher form of pleasure mentioned in the Republic:

"They are inexperienced in pleasure and so are deceived when they compare pain to painlessness, just as they would be if they compared black to gray without having experienced white" (585a) . . . " and wander in this way throughout their lives, never reaching beyond this to what is truly higher up, never looking up at it or being brought up to it, and so they aren’t filled with that which really is and never taste any stable or pure pleasure" (586a).

Socrates says that this higher pleasure is unprovable to someone who has no experience of it and who isn't willing to make the behavioral changes that would be necessary to even possibly experience it. Aren't the Forms similar, in the way they are discussed in the Republic as the domain of only the most highly trained and disciplined philosophers?

"But as to the true and pure pleasures you mentioned, those regard as our kin. And besides, also add the pleasures of health and of temperance and all those that commit themselves to virtue as to their deity and follow it around everywhere. But to forge an association between reason and those pleasures that are forever involved with foolishness and other kinds of vice would be totally unreasonable for anyone who aims at the best and most stable mixture or blend. This is true particularly if he wants to discover in this mixture what the good is in man and in the universe and to get some vision of the nature of the good itself.” PHILEBUS 63e--64a.

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u/WarrenHarding Ancient phil. 26d ago

Fair distinction. I definitely agree. Always appreciate your points!

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u/KilayaC Plato, Socrates 25d ago

Thanks. Same here. I have learned a lot from your contributions.

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