Issues among Presocratics studied so far: change vs. permanence. Milesians looked for a permanent reality underlying change. They thought that change was real, but could be understood only in terms of something permanent.
Heraclitus found change itself to be the only thing that was permanent. The search for a permanent material substratum is illusory, he thought.
Now comes Parmenides a turning point in the history of western philosophy - for he denies the reality of change. For Parmenides, change is impossible. The very notion of change is incoherent.
This is not just an assumption that Parmenides makes. Nor is it based on observation. (Quite the contrary: things certainly do appear to change.) Rather, it is the conclusion of a strictly deductive argument, from more basic premises.
And it is not the only startling conclusion Parmenides draws. For he also holds that there is no coming into existence, or ceasing to exist. According to Parmenides, everything that exists is permanent, ungenerated, indestructible, and unchanging.
According to traditional interpretation (no longer universally accepted, but still common) Parmenides goes even further, denying that there is such a thing as plurality. On this view, Parmenides denies that there are many things, maintaining instead that only one thing exists. (Its not so clear, however, what he thought this one thing is.)
Parmenides is without doubt the most difficult and obscure of the Presocratics. There are numerous different and conflicting interpretations of the curious bits of prose, poetry, and argumentation in the surviving fragments of his work, The Way of Truth. I wont try to canvas them all. Ill just sketch out one line that makes some sense of what Parmenides says.
Parmenides was a native of Elea, a Greek city in southern Italy (somewhat
south of present day Naples), born about 515-510 B.C. His great work consists
of a poem in two main parts. 154 lines of this poem have survived, almost
all of which is from the first part. (Experts think that about 90% of the
first part has survived.) The two parts of the poem correspond to what Parmenides
called the two ways.
Parmenides distinguishes two routes orways or roads of inquiry. He then argues against one of these, and in favor of the other. The one he favors he calls The Way of Truth; the other he says is a path entirely unable to be investigated. His argument is contained in fragments 2, 3, 6, and 8:
Come now, I will tell you ... the only routes of inquiry that are for thinking: the one, that it is and that it is not possible for it not to be, is the path of Persuasion (for it attends upon Truth), the other, that it is not and that it is right that it not be, this indeed I declare to you to be a path entirely unable to be investigated: For neither can you know what is not (for it is not to be accomplished) nor can you declare it. [2=B2]
For the same thing is for thinking and for being. [3=B3]
It is right both to say and to think that it is what-is; For it can be, but nothing is not. [6=B6]
Just one story of a route is still left: that it is. [8=B8]
Before we proceed, we must answer the following questions:
The most plausible answers are:
But the most plausible, and most popular, way of interpreting Parmenides is with the existential is. For is in the predicative sense is incomplete. If you say It is you havent made an assertion. It is what? is the appropriate response. But is in the existential sense means exists, and hence it is complete. It is means it exists, and this is a complete assertion.
What follows is an argument against the second alternative (1b):
It is possible for x to exist iff it is possible for x to be thought about (i.e., iff x is conceivable).
(5) collapses the distinction between what can exist and what does exist:
What can exist, does exist. What does not exist, cannot exist.
Parmenides is offering an argument in support of his central thesis:
(CT) That which is not cannot be thought about or spoken about.
In this first stage, he presents his argument. In stage 2, he will go on to draw the logical consequences of CT. Note that there are three crucial ideas involved here:
Parmenides two premises link these ideas. One premise (step (4) in the argument) links (b) to (c): what can be thought of = what can exist. The other premise (step (5) in the argument) links (a) to (b): what can exist does exist; what is, must be. Taken together, the two premises link (a) to (c): what can be thought of = what actually exists.
a. A thing can be thought about only if it is possible for it to exist. [= step (4) above]
b. Anything that does not exist, cannot exist. [= step (5) above]
But (b) is equivalent to:
c. Anything that can exist, does exist.
From (a) and (c) it follows that:
d. A thing can be thought about only if it exists.
And (d) is equivalent to:
e. Anything that does not exist, cannot be thought about. [= (3) above]
Tx: x is thought about
Ex: x exists
: it is possible that
|a.||∀x (Tx → Ex)||Premise|
|b.||∀x (¬Ex → ¬Ex)||Premise|
|c.||∀x (Ex → Ex)||From (b) by contraposition|
|d.||∀x (Tx → Ex)||From (a) and (c) by hypothetical syllogism|
|e.||∀x (¬Ex→ ¬Tx)||From (d) by contraposition|
Parmenides does not allow that you can think about what does not actually exist but could possibly exist. His argument rules out any distinction between what is and what is not but might be. Parmenides (as Ring says) collapses modal distinctions. For him:
what is possible = what is actual = what is necessary.
As Parmenides says (2): it is and ... it is not possible for it not to be. What is cannot possibly be otherwise. What can exist does exist, indeed must exist.
Parmenides is posing constraints on language and on thought, a limit on what can be spoken of or thought about: we cannot speak or think about things that are not (real), that do not exist. That means that much of what goes by the name of speaking or thought really wont count as such for Parmenides. If you do anything that Parmenides would call speaking or thinking of what is not, Parmenides would not even deign to call it speaking or thinking. For he could argue (along the lines that Plato suggested, cf. Sophist 237C-E):
If you are speaking of what is not, then what you are speaking about is nothing, i.e., is not anything at all. That is, you are not speaking of anything, which is to say that you are not even speaking. For speaking is always speaking of something, and in the (alleged) case of speaking of what is not there is nothing that is being spoken of. So there is no such thing as speaking of what is not.
An exactly similar argument could be used to establish the conclusion that there is no such thing as thinking of what is not.
It is clearly a formally valid argument. But is it sound? The first premise seems plausible: how could a thing exist if it is not even possible to speak or think about it? And how could one speak or think about something that could not even possibly exist?
But what of the second premise [(5) in our reconstruction of Parmenides argument]? It seems false to say that only what actually, in fact, exists could possibly exist. Why should Parmenides believe this?
i.e., for any object, necessarily, if it doesnt exist, then it doesnt exist.
∀x (¬Ex → ¬Ex) [ means it is necessary that.]
i.e., for any object, if it doesnt exist, then its non-existence is a matter of necessity.
∀x (¬Ex → ¬Ex)
(i) is true, indeed a truism. But, as we have seen, the argument requires (ii); and (ii) is false.
All (i) tells us that that it is impossible for there to be a world whose population includes things that do not exist in that world. This is (trivially) true. There is no world whose existents do not exist in that world.
But what (ii) tells us that that it is impossible for there to be a world whose population includes things that do not exist in the actual world. This is a substantive claim, almost surely false, that does not follow from (i). It is by no means obvious that there is no world whose existents do not exist in the actual world. (E.g., your parents might have had one more child than they actually did.)
Suppose something does not exist. How, then, would it be possible for it to exist? Can it come into existence? No, for there is nothing for it to come into existence from. So if it doesnt now exist, its never going to come into existence, and it couldnt possibly exist.
This line of reasoning has a certain plausibility, and it would certainly have appealed to Parmenides (cf. fr. 8: For what birth will you seek for it? How and from where did it grow?). But it is clearly defective, for two reasons:
But Parmenides has overlooked the possibility that a thing can come into existence from something else. This would be neither from itself, nor from nothing; since it would be from a different being, it would, in a way, be both from a being and from a not-being. It would come into existence from a different being, and from not having itself previously existed. [This is a possibility that Aristotle pursues.]
There is another possible reason why Parmenides might have believed that it is impossible to talk or think about what does not exist. One might find another argument for the Central Thesis, inspired by B8, lines 34-35:
Thinking and the thought that it is are the same. For not without what is, in which it is expressed, will you find thinking.
The idea is that thinking just is thinking of something that exists. An argument for CT along these lines might look like this:
|a.||S is thinking ↔ S is thinking of something.||premise|
|b.||S is thinking of something ↔ There is something S is thinking of.||premise|
|c||S is thinking of what does not exist ↔ There is nothing S is thinking of||premise|
|d.||There is nothing S is thinking of ↔ S is thinking of nothing.||From (b), by contraposition|
|e.||S is thinking of nothing ↔ S is not thinking.||From (a), by contraposition|
|f.||S is thinking of what does not exist ↔ S is not thinking.||From (c), (d), (e), by hypothetical syllogism|
As noted above, this seems to be the way Plato interpreted Parmenides; cf. again Sophist 237C-E, where what is at issue is saying, or talking about, rather than thinking. But the argument Plato supplies works the same way in the case of either speaking or thinking.
How should one respond to this argument? One response is to say that there is an ambiguity in the notion of thinking of something.
Thus, each of the premises needs to be evaluated in light of this distinction. (a) is plausible only if it concerns thought contents: if you are thinking, there must be a content to your thought; on the object reading, (a) begs the question. (b) is plausible only if both antecedent and consequent involve the same sense of thinking of something. For (c) to play any role in the argument, however, its consequent must concern thought contents, and its antecedent must concern thought objects: if there is no existing object that S is thinking of, then there is no content to Ss thought. But, so interpreted, (c) is both question-begging and equivocates on the notion of thinking of something.
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Copyright © 2003, S. Marc Cohen