Descartes Question

Great Debates
21

Hey, I am not Descartes, and I don’t agree with him. I’m just trying to argue against (what I consider to be) misinterpretations of his argument.

The cogito cannot be an axiom in the sense that I understand the term.

  1. If it is an axiom, it is only true by definition within a specific theory. Descartes claims it is true outside the theory. You can say that it is not necessarily true, fine by me, but that doesn’t make it an axiom. That only makes it false or undecided. Cogito ergo sum implies a factual claim.
    It differs from 1=1=2 which only states formal equivalence of terms. Cogito ergo sum means: from the ‘I think’ can be inferred that ‘I exist’, and implies that the factual statement ‘I think’ is correct.

  2. Furthermore, I don’t see that the empirical truth (fact) that the cogito implies is wrong: I do think and I do exist. If you claim that a methodical doubt would even make those facts dubious, that’s fine by me. I’m not so well into Descartes right now that I can really debate such a statement. FWIW, I never had much problems with accepting the cogito. My problem was more that you cannot derive much interesting knowledge on that basis alone.

  3. The real issue, leaving terminological debates aside, is whether the cogito is a necessary truth. I’ve never claimed that it is a necessary truth, I only claim that Descartes thinks it is a necessary truth. And as I understood the word ‘axiom’, an axiom is not a necessary truth. So the label is formally incorrect.

22

“I think therefore I am” is certainly an axiom as Descartes used it. In responce to each of your points:

  1. Labeling “I think, therefore I am” a “factual claim” or “incontrovertable truth” or whatever doesn’t do anything to change the way Descartes USES it. He uses it as an unproven statement used to prove other statements, i.e., axiomatically.

If “I think therefore I am” was actually OUTSIDE of Descartes’ logical system, it couldn’t be used to prove anything. Descartes DOES use it (and a plethora of other assumptions) to prove things about reality, and about God. Because he is using this statement as if it was an axiom of his theory, it doesn’t matter whether he SAYS it’s not- logically, it is one.

  1. If you are saying (1) you also operate under the axiom “I think therefore I am” and (2) you don’t think much can be derived from that statement alone, then I totally agree with you.

  2. Just because Descartes thinks an axiom is “necessary” doesn’t make it a non-axiom. In Euclidian geometry, the axiom “parallel lines never meet” is necessary for a large number of proofs. In set theory, the axiom “From any set, a smallest member can be chosen” is necessary for a variety of proofs, but it’s still an axiom.

Descartes is doing exactly the same thing- he thinks “I think therefore I am” is necessary for certain conclusions about reality. I suspect what Descartes is trying to do is what every other philosopher who understands the destructive power of logic tries to do- find some fundemental axioms (assumptions) that nearly all human beings unconciously make.

-C

23

You find the cogito unproven. I won’t dispute that it may in fact not be proven by Descartes. But again it seems clear to me that Descartes thinks he does prove the truth of the ‘sum’ from the fact of the cogito, which fact is clear for everyone who thinks. If you don’t think that is clear, I don’t know how else to convince you and we’ll have to agree to disagree.

I think (!) we are in fact in agreement here. :slight_smile:

You seem to use necessary in a different sense than the one common in philosophy.

In philosophy it is used to mean something that is absolutely necessary. A necessary truth is a truth that could not be otherwise (whatever that is supposed to mean). (You may think this is nonsense, which may be right, but I am trying to explain what Descartes thinks he is doing.).

The specific Euclidian axiom is only necessary for Euclidian geometry (indeed, it defines Euclidian geometry). And that axiom is only conditionally necessary to derive certain propositions. The axiom is emphatically not true absolutely, as you are well aware.

Again, you may disagree whether the cogito is a necessary truth (I’m not sure myself), or whether such truths exist at all. But it , seems clear to me that Descartes thinks the cogito it one. Descartes was not interested in building a mathematical system that is only true once you accept the axioms. he was interested in knowledge and truth and thought he had an absolute truth with the cogito that was factually and ‘necessarily’ true. (BTW I’m not sure whether Descartes would use the term ‘necessary truth’)

You may also disagree with the philosophical use of these terms and find them unhelpful or misleading in comparison with mathematical usage. You may find them nonsense for all I care. But bear in mind that we are in a thread that did not ask: is Descartes right? or Are philosophical terms correct? The OP asked what Descartes did in a specific part of his proof, and I set out to answer it on those terms. I’m not interested in broadening the debate to philosophical terminology. Seems to me a philosophical debate may well use terms in the common philosophical manner.

24

Back to the original question: once you ask for validation of your reasoning itself, you’ll find you have nowhere to go. No argument can be formulated without using reason. Stated another way, every logical argument has the implicit, built-in, unremovable assumption “assuming my reason is not being deceived.” The validity of a logical argument is completely contingent on the validity of reason, so this statement needs to be true for any logical argument to make sense. On the other hand, this assumption cannot be proved because such a proof (just like any other proof) would itself require the use of reason, and would therefore be circular. It’s completely useless to doubt the validity of reason; it does not lead to any interesting distinctions. Perhaps you can’t know that you can trust your reason, but you can’t get anywhere without assuming that you can.

Trom, did Descartes actually mistrust his reason itself? Somehow I only recall him mistrusting his worldly senses and the apparent existence of the world around him. (Actually, I’m not even sure I’ve read the first Meditation; I forget the names of his works.)

25

In order to think about philosophy, there needs to be thinking in the first place. That’s where “I think” comes from. Once I have this, it immediately draws attention to the fact that I exist (otherwise, there would be no “I” to do the thinking). “I think; therefore, I am.” Notice that it is, indeed, an argument and not merely the statement of an assumption.

The fact that it wasn’t proved using rules of Aristotelian logic does not necessarily imply that it is an unproved assumption. The argument “I think; therefore, I am” is not an argument of Aristotelian logic; it’s actually a far more sophisticated argument than Aristotelian logic would allow on its own. The primary thrust behind the argument “I think; therefore, I am” comes from the ability of reason to reflect on itself. This type of reflection is simply not captured in Aristotelian logic. It is true that Aristotelian logic, a priori, cannot derive any truths with content; the only truths that can be derived are the tautologies of the logic. Other truths can only be derived if some assumptions are made. However, Descartes’s reason is not limited to this restricted mode.

26

Isn’t there something of a self referencing error here? If you accept that logical truth requires unprovable axioms to be a useful tool, and that therefore there are no “Objective truths”, have you not made the same mistake by implying that the limitations of logic is itself a “Necessary truth”?

IOW I’m asking if the statement “there isn’t an objective truth” is not itself either a tautology or an “Incontrovertable Truth”. And by your terms, therefore, either “meaningless” or an objective truth.

27

And then someone went and used “postulate” as a nown, and the whole neighborhood went to shit.

28

I enjoyed that thread very much, as I enjoy all discussions of hyperbolic doubt, except when people don’t doubt as much as they say they are. Ramanujan gave a nice summary, but it is also important to consider the context Descartes was working in.

The meditator would essentially release everything he could through methodological doubt, until the bedrock remained that the only way one could do this was to “realize” that one must exist in order to be doubting in the first place. This was the source of the cogito ergo sum statement, even though it was never stated that way in the meditations themselves. Descartes/the meditator then went on to ponder perfection, and concluded that the idea of a perfect god couldn’t have come from him since he’s so durned imperfect, and so must have been planted there by the perfect god. Since there’s a perfect god, then, there is no great deceiver and he can happily return to the world he just got through saying was possibly illusory.

As a proposition of logic, cogito ergo sum fails spectacularly for various reasons (but not various reasons simultaneously). It is purely tautologous since the ‘I’ is both in the premise and the conclusion: circular reasoning. This is not necessarily a problem as all logical arguments are manipulations of tautologies. In fact, so long as we disregard what ‘I’ means, the proposition holds (by definition, thought requires a thinker). But Descartes wanted to keep some semblence of ‘self’ tied to this ‘I’, and so it ceased to be a bedrock and required concepts and relationships external to the proof to be true—the very things he supposedly just disregarded.

One argument might be that the ‘I’ in the subject and the ‘I’ in the conclusion are only the same symbol but they are not meant to refer to the same thing. That is, that the ‘I’ in the conclusion is stronger or more encompassing than the ‘I’ in the subject.

Detractors of Descartes do not strictly say he was wrong; rather, many feel it is trivial—of course perceiving needs a perceiver. The strength of Descartes argument, seen in this light, requires one to accept the following proposition: “I cannot possibly be wrong that I am perceiving.” Yet again we find the ‘I’ littered around. Any attempts to remove the ‘I’ from portions of the statement, and thus avoid circularity qua circularity or circularity based on the multiple uses of ‘I’ in natural language, results in a statement that Descartes, and supporters of, will not accept as what they mean.

Suppose we revised the argument and stated the following. One, the proposition “thought requires a thinker.” Two, “there is thought.” The conclusion we reach here is, “Therefore there is a thinker.” Not, “Therefore I am thinking.” Notice there is no room made for the symbol ‘I’. It is wrong to insert it into the conclusion. If we try to place it in earlier, we get the result of (rephrasing the second assumption), “I have thoughts.” But that is just what we’re trying to prove.

I think that is certainly one way to approach the problem of his arguments, yes. He is, on one hand, rejecting the idea that the contents of his thoughts have any power of implication, then on the other hand, using his thinking as implying a thinker.

29

Thanks for all of the replies. I think I was confusing an argument made by Al Ghazali in Deliverence from Error with Descartes’. Al Ghazali loses faith in his ability to reason and falls into a sort of despair until God supposedly clears it all up for him.

"Such thoughts as these threatened to shake my reason, and I sought to find an escape from them. But how? In order to disentangle the knot of this difficulty, a proof was necessary. Now a proof must be based on primary assumptions, and it was precisely these of which I was in doubt. This unhappy state lasted about two months, during which I was, not, it is true, explicitly or by profession, but morally and essentially, a thorough-going skeptic.

God at last deigned to heal me of this mental malady; my mind recovered sanity and equilibrium, the primary assumptions of reason recovered with me all their stringency and force. I owed my deliverance, not to a concatenation of proofs and arguments, but to the light which God caused to penetrate into my heart—the light which illuminates the threshold of all knowledge."