Placeholder Image

Subtitles section Play video

  • Professor Shelly Kagan: We've been working our way

  • through Plato's arguments for the immortality of the soul.

  • And last time I spent a fair bit of time working through

  • objections to, not quite the last argument

  • we're going to look at, but the penultimate argument,

  • in which Plato tries to argue for the simplicity of the soul.

  • The set of connected ideas, you'll recall,

  • were these: that Plato wants to suggest that in order to be

  • destroyed you've got to have parts;

  • to destroy something is to basically take its parts apart.

  • If he could only convince us that the soul was simple,

  • it would follow that it was indestructible and,

  • hence, immortal. He asks, what's our evidence

  • for some things being indestructible?

  • What kinds of things are simple? Well, these are--he then goes

  • on to claim--invisible things, things that don't change.

  • After all, changing is a matter of the rearrangement of the

  • parts. And so, if something can

  • change, it can't be simple. Maybe it could be destroyed.

  • But if we could become convinced that the soul was not

  • composite, if it was something that couldn't change,

  • then it would simple. Perhaps then it would

  • indestructible. And then he goes on to suggest

  • that the invisibility of the soul is evidence for it's being

  • changeless, and hence simple, and hence indestructible.

  • So that's the argument we worked through last time.

  • And I spent a fair bit of time suggesting that if you pin down

  • precisely what Plato means by invisible, the argument doesn't

  • actually go through. Before leaving that argument,

  • there are a couple of extra remarks I want to make about it.

  • First, we probably shouldn't have been so quick to want to

  • buy into the suggestion that the soul is changeless.

  • After all, if you think about it, it seems that at least on

  • the face of it the soul does indeed change.

  • On one day you believe, for example,

  • that it's hot; on another day you believe that

  • it's cold. On one day you believe that so

  • and so is a nice person; on the next day you believe

  • that so and so is a mean person. You desire to learn the piano,

  • the next day you give up on that desire.

  • Your beliefs, your goals, your intentions,

  • your desires--these things are all constantly changing.

  • And so, at least on the face of it, it looks as though we might

  • well want to say the soul--if we do believe there are souls--the

  • soul is changing as well, in terms of what thoughts and

  • beliefs it's housing. So we should have been

  • skeptical in the first place of any argument that said,

  • based on the invisibility of the soul, we can conclude that

  • it's changeless. It doesn't seem to be in fact

  • changeless. Furthermore,

  • we should be, or at least we might well be,

  • skeptical of the claim that the soul is simple.

  • Indeed, Plato himself, in other dialogues,

  • argues against the simplicity of the soul.

  • Now, that doesn't mean he's right in the other dialogues,

  • but at least suggests that we shouldn't be so ready to assume

  • that sort of position is correct.

  • In The Republic, famously, Plato goes on to

  • argue that the soul has at least three different parts.

  • There's a rational part that's in charge of reasoning;

  • there's a spirited part that's sort of like the will;

  • there's a part that has to do with appetite,

  • desires for food, drink, sex, what have you.

  • Plato elsewhere argues the soul is not simple at all.

  • So perhaps it shouldn't shock us that the argument he's

  • sketching here for the simplicity of the soul based on

  • the changeless, invisible nature of the

  • soul--perhaps it shouldn't shock us that that argument doesn't

  • succeed after all. Finally, although I gave Plato,

  • previously, the assumption that if only we could establish the

  • simplicity of the soul, it would follow that soul was

  • indestructible--after all, you couldn't break a soul by

  • tearing its pieces apart if it didn't have pieces,

  • if it didn't have parts--nonetheless,

  • I just want to register the thought that it's not actually

  • obvious that simples can't be destroyed.

  • Well, they clearly can't be destroyed by the particular

  • method of destruction that involves taking them apart.

  • If they don't have parts, you can't take them apart.

  • But for all that, it still seems conceptually

  • possible for a simple to be destroyed in the following

  • sense: it goes out of existence. After all, where did the

  • simples come from in the first place?

  • Well, at least from a logical point of view,

  • it seems as though there's no difficulty in imagining that at

  • one point a given simple didn't exist and then at the next point

  • it popped into existence. Well, how did that happen?

  • Maybe God said--God says at the beginning of Genesis,

  • "Let there be light." So maybe He says,

  • "Let there be simples." At a given moment they weren't

  • there; the next moment they were.

  • Well, after a while maybe God says, "Let the simples no longer

  • exist." Given moment there they were;

  • the next moment, they no longer exist.

  • Seems as though that idea makes sense, and so even if we agreed

  • that the soul was simple, even if we granted everything

  • in Plato's argument up to this point and said,

  • "the soul really is simple," it still wouldn't follow that it's

  • immortal. We'd still have to worry about

  • the possibility that the simple soul might simply pop out of

  • existence at a given point, perhaps the very point when the

  • body gets destroyed. So I'm inclined to think that

  • this most recent argument of Plato's--the argument from

  • simplicity--no, that's not successful either.

  • Before leaving that argument, there's one other piece

  • of business I want to discuss. This is a footnote that I put

  • aside, a point that I put aside previously.

  • You'll recall that we were worried about--The objection got

  • raised the right way to think about the soul is like the

  • harmony of a harp. And this was originally offered

  • as a counterexample to the thought that invisible things

  • couldn't be destroyed. But harmony could be destroyed.

  • It was invisible, so invisible things could be

  • destroyed. But I noticed,

  • I mentioned that, look, whether or not this is a

  • problem for the argument, it's an interesting suggestion

  • in its own right. Because the suggestion that the

  • mind is to the body, the soul is to the body,

  • like harmony is to an instrument with strings,

  • seems to me to be an early attempt to describe something

  • like the physicalist conception of the mind.

  • Just as harmony is something that gets produced by a

  • well-tuned instrument, the soul or the mind is

  • something that gets produced by a well-tuned body.

  • Now Plato's got some objections to the suggestion that we should

  • think of the mind as the harmony of the body.

  • And so I want to take just a moment and talk about those

  • objections because, of course, if they were

  • compelling objections that might well give us reason to doubt the

  • physicalist view. Whether or not Plato's

  • arguments for the immortality of the soul work,

  • he might still have some good arguments against the

  • physicalist conception. But in thinking about these

  • objections, it's important to bear in mind that it's only

  • meant--the harmony analogy is only meant--as just that,

  • as an analogy. Right?

  • The claim isn't, or at least it shouldn't be,

  • understood as saying literally, "the mind is harmony."

  • It's rather, the mind is like

  • harmony; it's the sort of thing to the

  • body like harmony is to a harp, something that can be produced

  • by a well-functioning, well-tuned physical object.

  • A well-tuned instrument can produce melody and harmony.

  • A well-tuned, properly functioning body can

  • produce mental activity. That's the suggestion.

  • And so even if it turns out that there are some ways in

  • which the mind isn't exactly like harmony,

  • it doesn't show us that the physicalist view is wrong.

  • Well, so let's quickly look at what Plato's arguments were.

  • First--this is, I think, an interesting

  • argument--Plato says, harmony clearly cannot exist

  • before the existence of the harp itself.

  • Right? The melodiousness of the harp

  • can't exist prior to the physical construction of the

  • harp. And if mind were the sort of

  • thing that was produced by the proper functioning of the

  • physical body, then pretty obviously the mind

  • could not exist prior to the creation of the physical body.

  • However, Plato has already argued earlier in the dialogue

  • that the soul does exist prior to the existence of the body.

  • That's the argument from recollection.

  • If the soul exists prior to the body, it can't be like harmony;

  • physicalism has clearly got to be false.

  • But I said that I didn't find the argument--I tried to explain

  • why I didn't find the argument from recollection persuasive.

  • I certainly do want to agree that if we became convinced that

  • the soul did exist prior to the existence of the body,

  • we would certainly want to agree that the soul is not like

  • harmony. But I don't think the argument

  • from recollection succeeds.