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Plato on Immortality 1

Updated on June 5, 2014
Bust of Plato
Bust of Plato

A priori knowledge and immortality

Plato's proofs are mainly in his dialogue Phaedo, with two more included in the Meno and the Republic.

Plato believes that we have a kind of knowledge known as a priori. We will now define what this means. Although surprising at first, this claim can be supported. There is an issue as to whether there are alternative explanations besides the one Plato needs for his proof of immortality to work.

A priori knowledge is the knowledge we have regardless of experience. To know that p (where p is the meaning of a sentence) is defined, for our purposes, here as meaning that p cannot possibly be false. The traditional view was that only logically necessary truths can be known in this strong sense of "know" but matters turn out to be more complicated. Additional criteria for what counts as knowing that p include: fully satisfactory justification of the claim that p is true; incorrigibility (impossibility of correcting the view that p is true); and actual truth of p. Yet, ingenious counterexamples to all of the above have been produced, showing that we may still lack basis for claiming that we know p even in spite of the justification, incorrigibility, and actual truth of p. Plato, however, apparently works with this JIA (justification-incorrigibility-actualtruth) model of what p must be if it is to be known. Moreover, as a so-called epistemic Realist, Plato takes it that p can meet all of the above and, as such be knowable, regardless as to whether there is anyone who actually knows that p. Regarding the earlier point about the connection between logical truth and a priori knowledge (knowledge regardless of experience): here is an example of the two going in different ways: I surely know regardless of experience that I am something or other that is engaged in having the thoughts I have right now. This statement (that "I am doing this right now, etc....") cannot be corrected; it is known a priori. Yet, this is not a logical truth. (By logical truth let's take one whose truth is fixed because of the meanings of the words in the sentence: e.g. "a triangle has three angles.") For Plato, epistemology and logical truth do go together. There is even a push toward the view that it is ultimately the nature of things or the universe (totality of things) that sets down the proper logical truths. Pushed further, this would have the implausible consequence that all actual truths are necessarily true! But another way of placing Plato on this map is this: the distinction between actual and necessary truth may be blurred in this view. Plato does distinguish between what he calls real or proper (perfectly attested) truth and notions that are true to a lesser degree. This is an odd view but Plato appears to subscribe to it. "A geometrical triangle's angles add to 180 degrees" is perfectly true (in Greek "ontos on") but "this human-made triangle right here, being imperfect as it is, has angles that up to 180 degrees" is not perfectly true; it is true-ish, as we would say, or true to a degree.

The take-away point we need for the immortality proof is this: knowledge can be only of statements that are perfectly true. We couldn't have notions about imperfect triangles unless we had the standard of perfect knowledge. To assess the statement "this triangle has angles adding up to 180 degrees" as true to, say, 89% of the truth-continuum, we must somehow have the ability to apprehend the fixed standard - or to "get it" that it is the statement about the perfect, abstract, triangle of geometry that is completely true.

Yet, we cannot have access to perfect geometric triangles through our bodily senses. When we use diagrams we are only assisting our handicapped mental abilities. Visual proofs should not count in geometry. The Greeks did count them, albeit reluctantly, but the view that visual proofs can be properly included is rare today among students of math or logic.

If we cannot possibly have access to abstract perfect objects, like triangles, through our senses, then how do we have such access at all? In other words, how is a priori knowledge (knowledge regardless of experience) possible? To be further persuaded that we do have such knowledge consider this: suppose that, on an alien planet, we experience a bizarre phenomenon which, however, remains regular and reproducible: every time we take one and another item of the same kind we instantly are left with one such thing (not two)! Does this mean that babies born and raised there would learn as an incorrigible truth "1 + 1 = 1" instead of "1 + 1 = 2"? In that case, why don't we consider that we have made a discovery - that "1 + 1 = 1" is possibly true after all? We insist that the second item disappears; but this means that we are adamant about not letting experience correct the accepted truth that "1 + 1 = 2". The case of the babies is instructive too. The baby should already be uncomfortable with the situation - cheated of a toy, perhaps, if the items are toys - even though the baby has never been taught math. This is an example of a priori knowledge. You can think of the whole body of mathematical knowledge as being a priori. On the other hand, contingent truths about how the world actually works are not known a priori (they are known, as we say, a posteriori) - but recall the exception of the first-person indexical statement above...

To recap: Plato needs the claim that we have a priori knowledge - knowledge that cannot be corrected by experience - and this knowledge has to be attestable by means of standards laid down by abstract objects (like geometrical triangles in the preceding example.) These abstract objects do not include only mathematical objects but also the predicates we check whether we should attribute (to some degree) or withhold (to some degree, or altogether) when we assert statements about subjects: "X is brave," "X is just," "X is beautiful," etc. These abstract objects are the famous Platonic Forms. Plato takes them to be objectively real though not confined by space or time at all.

Traditional bust of Socrates, the inexorable interlocutor in Plato's dialogues.
Traditional bust of Socrates, the inexorable interlocutor in Plato's dialogues.

Knowledge and Immortality

As we saw, the availability of a priori knowledge means, for Plato, that we must have access somehow to the proper abstract objects - like the triangles - which lay down the standards on which we assess truth-claims. In the juggle, there are no perfect triangles at all; yet the primitive tries to hone shapes that approximate the abstract geometrical ones. This a priori apprehension of the geometrical figures means, Plato thinks, that we have access to the extra-empirical, abstract objects. But only like can interact with like. This is one of the premises of the argument. Things whose compositions are at metaphysical variance, cannot "touch" so to speak. Of course the abstract, immaterial objects do not have surfaces and, as such, cannot touch or be touched. We are reduced to using metaphors often when we discuss the Platonic theory of the Forms.

To be the kind thing that can apprehend the abstract objects means to be like them. But, in that case, we are the kind of thing that is not confined by spatiotemporal restrictions, notwithstanding the entrapment of our abstract essence by a material body. We are essentially souls -- with the underlying assumption, of course, that it makes sense to speak also of what something is essentially. This further means that we do not abide if we destroyed as souls - because this is what we are essentially - but we abide if our bodies are destroyed in the same way an item is the same item and not a different one when it is painted a different color (since color is not an essential property.) Now comes the punchline. We cannot be destroyed precisely because we are souls. Souls are indestructible, as we are ready to see.

The soul is like the abstract objects it apprehends directly - "eye to eye" if we are to speak metaphorically again. (This emphasis on direct apprehension reveals a mystical component in Plato's philosophic system.) Like the objects, whose nature it shares, the soul cannot be destroyed because it cannot even change - and change is necessarily presupposed if something is to be changed so as to be destroyed. The reason for the indestructibility of such abstract objects is that they are outside of temporal constraints. They are immune to moment-after-moment succession conditions and, as such, they are immune to change. Indeed, the abstract triangle of geometry is such a thing: it is absurd to query whether a geometrical triangle is still the same since the last we were talking about it. And, looking toward our relative future, it is as absurd to anticipate that the geometrical triangle may no longer be what it once was next time we might be making references to it.

The person experiences changes because of the body within which the soul is entombed, as Plato likes to say. (There is a problem, here, about how the soul can experience change at all! Also, the broader interaction problem makes an appearance: how can an abstract and immaterial think interact at all with a concrete and material thing?) The soul itself is immune to change, and, as such, indestructible.

What Exactly Has Been Proven?

Does this count as a proof that the soul exists? Or as simply a proof that, assuming that it exists, the soul is immortal or indestructible?

Straightforwardly, the proof tries to establish the conclusion that the soul, as defined, is indestructible. Whether the soul exists in the first place is left for other proofs. The proof itself proceeds by analogy to the abstract objects of proper knowledge. In spite of that, it is not an inductive proof. An inductive proof proceeds from empirically based premises (1) that X has attributes a, b, c and (2) Y has attributes a, b to the conclusion: Y probably also has attribute c. Some count all analogies as inductive but this seems wrong since analogies can be drawn without recourse to experience and with an added premise - more like an abstract principle: "things that share attributes a and b must also share attribute c if either one has this third attribute." One could actually refrain from calling this kind of argument an analogy, if one so wishes.

In a deductive argument, we check for validity (whether the characteristic logical pattern of the argument is such that IF all the premises are true then the conclusion MUST be also true); once the validity test is passed, the remaining test is for soundness: are the premises to be conceded definitely as being true? Plato's arguments, if deductive, may pass the validity tes (although this is not always the case) and fail when it comes to the soundness test. There always seems to be some available objection one could raise as to the actual truth of some Platonic premise or other. It is not surprising, of course, that we don't have knowck-out philosophic arguments of immortality. It might actually be more surprising that we have any such arguments at all - and the argument we have presented here is one such argument.

Problems with the Proof

A historically famous critique is the "tabula rasa" or "blank slate" view defended spiritedly by john Locke. This view denies a priori knowledge but, in the sense of apriority as incorrigibility, it seems that human knowledge accesses claims that are incorrigible by experience and, thus, a priori.

Plato explains availability of apriori knowledge by means of the theory of abstract objects or the Forms. One question that can be raised is whether there are alternative explanations. Evolutionary theory can account for a priori knowledge in the specified sense: the mental operations that make a priori knowledge available must have been selected in the course of evolution, within a dynamically changing environment, for the advantage for survival and reproduction, which such abilities afford the intelligent animal. Plato's alternative explanation seems to violate the principle of Ockham's razor as the theory of the Forms multiplies entities beyond what the rival theory needs.

Any critique that can be leveled at the theory of the Forms may be introduced here as a critique, broadly, of the proof of immortality we have been considering. An ancient critique is by Aristotle who complained that the theory "duplicates" the real things, fails to account for how the "separate" Forms can also be participated-into by the concrete objects of our experience, cannot account for the energy or force needed to impart the Forms onto the objects of concrete experience, and runs into other notorious troubles when it tries to account for relational properties (properties like "x is F-related to y," or "x is G-related-to-y-and-z.")

The proof does not establish existence of the soul, or the claim that a person is essentially a soul. The tradition has a related proof that aims at supporting an existential conclusion: anything that is not confined within spatiotemporal constraints cannot be depending on anything else but iself for its existence. Non-dependence is established because any dependence-relation requires necessarily spatiotemporal involvement. (This, however, seems to create a problem for Plato's theory of the Forms because the Forms are supposed to be related to each other so that, for instance, different predicates can be co-attributed to the same subject.) Given that an abstract object like the soul does not depend on anytning other than itself for its existence, then it cannot fail to exist. It is not clear how this last claim is to be supported. As a postulate, this claim found its way into a later philosophic work, Spinoza's Ethics.

The premise "only like can know like", which we found to be needed for the proof, can also be attacked. If this, or any other premise, is not to be accepted as true, then the argument, even if valid, is unsound; as such, the argument fails to be persuasive to the rational student of thought.

Knowledge and the Soul

Can there be knowledge (defined as incorrigible) if the person is not an abstract entity?

See results

Athens, Greece

© 2014 Odysseus Makridis


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