I exist, but I can't prove it. 

I agree with you: if we adopt an attitude of radical doubt, to the extent that we even doubt that two plus two is four, then we should also doubt that whatever logic underlies "cogito, ergo sum" is true.  It sounds true that if there's a thought then there must be a thinker, but a lot of things sound true, and if we're doubting everything then we have to doubt our own logic too.  For that matter, maybe we're deceived that there's a thought in the first place.  Or maybe there is a mind doing the thinking, but it's not my mind.  We're not the first to make these criticisms of Descartes, by the way; we're preceded by philosophical luminaries including Soren Kierkegaard and Immanuel Kant.  I don't move in philosophical circles, but I expect in any given group of philosophers you could get a number to agree with you that "cogito, ergo sum" is not a logical proof if we begin from the position of radical doubt.

That said, based on what I do understand of my favorite branch of philosophy -- the philosophy of science -- it's out of fashion these days anyway to argue that anything can be known with perfect certainty.  All logic begins with premises, including but not limited to the premise that logic works.  You can't prove those premises without resorting to other premises, and so on back.  We have to start by making some set of assumptions that we agree are true without needing to prove them.  "I exist" may not be a proposition I can prove, but it's as good a place as any to start, since if I don't exist then I might as well not bother talking about philosophy. 

Actually, from a logical point of view, cogito is gibberish. The conclusion he's attempting to prove is his own existence. So what does he present as evidence? That HE is thinking. Which already assumes the conclusion he's trying to prove. I don't know the latin name for that fallacy off the top of my head.

As for proving our own existence, there's two ways to look at it. Either the proof is vacuous, because while Descartes' statement is bad logic, it's also intuitively as obvious as anything can possibly be, or such proof is impossible, because from the standpoint of radical doubt, no evidence that would support such a claim can be accepted as valid. You have to decide whether you accept the claim or not based on your own feelings on the matter, it's a question like whether god exists. It can't be proven or refuted.

Syora wrote:

I have never been well-versed in philosophy. But I have to ask, why is this question even important? How is it relevant to anything aside from being an exercise in logic?

Not much other than as an exercise in logic for some - turning these questions in one's head and with others helps one take a more critical and in-depth look at topics such as belief and truth, which can be extended to areas such as ethics and morality.  For the religious, existential debates hold even more weight. 

As for me, I like philosophy, as in reading it.  Debating it is certainty my weakness, since I never end up satisfied with one viewpoint or philosopher enough to back it with any real gusto or knowledge, yet am not confident enough to propose any theories of my own.

Well, I do find Alan Watts rather nifty.  He doesn't (at least from what I have read) seem to pay much attention to matters of existence (saying any arguments trying to discover God or truth are confounded by our language contexts -as soon as we name God we lose the essence of what God is, so on, so on; basically agnosticism) or ethics, but more like a way to look at and envision the world in way that brings a person happiness.  His book The Wisdom of Insecurity has helped me loads with my depression.

Last edited by OnlyInThisLight (03-02-2011 10:17:55 PM)

So, um, warning: I just finished a degree in philosophy. THIS THREAD IS LIKE CANDY TO ME

Stormcrow wrote:

Actually, from a logical point of view, cogito is gibberish. The conclusion he's attempting to prove is his own existence. So what does he present as evidence? That HE is thinking. Which already assumes the conclusion he's trying to prove. I don't know the latin name for that fallacy off the top of my head.

This point gets brought up a lot, but there is an intriguing counter-point: Descartes phrases it not so much that he himself IS thinking, but rather that, given the method of doubt he sets up, the very act of doubting any sort of reality points towards the existence of a thinking self that does the doubting/is persuaded of the dubious nature of perceptions/has those perceptions. It's certainly very circular in its way, and I agree with tuomastahti that it's actually taking a bit of a shortcut but it's not that terrible an argument given his premises (though he presents it in an absolutely rubbish manner).

Syora wrote:

But I have to ask, why is this question even important? How is it relevant to anything aside from being an exercise in logic?

Like a lot of big philosophical questions, it's only relevant to the extent that the person being asked finds it interesting. If you're not troubled by the thought of being unable to be certain of your existence, then the question appears quite lifeless and uninteresting. If, on the other hand, you've got some qualms about how "real" reality is, that sort of question can tantalise and tease your mind like nothing else. There's definitely no hard and fast rule that any philosophical question should or shouldn't interest anyone - for example, I am bored stiff by the Sorites Paradox despite liking paradoxes and logic in general, and that's just how it is for me.
Also, some of the assumptions about our own existence, if turned upside down, would make it very hard for many philosophers to have their theories retain coherence. So, there's probably a little bit of personal-pride motivation for some to have a good answer to that question.

tuomastahti wrote:

And if our logic isn't completely reliable, how can we prove our own existence?

This is the meatiest question ever and oh my do I want to sink my teeth in!

I think you definitely have an excellent point on the problem of having assumed that thinking requires presence. It's entirely possible that all of our thoughts and experiences could occur independently without some being existing to have them. We could very well not exist in any real sense at all, and be deceived into even thinking we exist. It would be a tangled, strange metaphysics you'd have to build to explain that kind of result, but I don't see a reason for it not to be achievable.

Personally, I've always approached the problem of existence from a more empirical, metaphysically-disinterested position: if all of our perceptions are up to be doubted, then our conclusions about those doubts, being informed by those perceptions, are also equally suspect. We can't be absolutely certain that we don't exist, and in fact any conclusion we make that says we don't is just as questionable as one that says we does. Even doubt must be doubted if we're to go about doubting properly. (Try saying that ten times fast!)

At the same time, we always seem to have access to our current mental states, including perception, knowledge, memory, and imagination, and they comprise the limits of our experience. Even if we don't exist (and we should doubt any conclusion that says we definitely don't), we still perceive ourselves as experiencing these perceptions. Though the conclusions we reach about our existence are all suspect, we're still having all of this experiences that suggest a physical reality whose existence is assured. These perceptions, which may be illusions and also may not be illusions, don't ever seem to present us with the data that we need to judge definitively that we do or do not exist in a real sense. But we always have the image of the physical/real presenting itself to us, and without any clear indicators as to its truth or falsity, we can only accept it as something we are experiencing. Even if what "we" are is something we don't have the full story of, we still have enough to suggest that acting in the world is something that we can do.

TL;DR - There's no proof one way or another, so taking the world as it presents itself and accepting the unknowability of its reality is probably the best way to roll?

(I am way out of practice and also bombed out from a long day at work. I apologise for all gaping logical holes)

And the best thing about that is, satyr, is that the philosophy of science descends directly from Hume's work on the problem of induction, in which he took on Descartes' notions of self and the limits of a rational basis for believing in our own existence! And Hume was the one who inspired my take on things, so basically all these ideas tie neatly to one another That is one of the things I love about questions like this - they always end up being connected to a whole bunch of other considerations.

Thank you very much for your reply, Almaser.

Almaser wrote:

At the same time, we always seem to have access to our current mental states, including perception, knowledge, memory, and imagination, and they comprise the limits of our experience.

This part made me think about what Socrates said: "I know that I know nothing." Isn't there a possibility that we actually do know something but we just don't remember it at the moment? Of course we could logically say that if we have forgotten something even temporarily, then we don't know it anymore, but we had assumed that logic can't always be trusted. Therefore, wouldn't the saying of Socrates be better in this form: "It seems that I know nothing." This may also be a bit problematic, but is there any better way to put it?

By the way, you were right when you said that "that sort of question can tantalise and tease your mind like nothing else".
All day long I think of things but (so far) nothing seems to satisfy.

Maybe knowledge isn't something for individuals to own, as it is something pre-established out there. Maybe it's like the Allegory of the Cave? Where there ARE ideal images of things out there, but we can only make less than ideal imitations of the true knowledge, so in a sense, we have yet to own any of the truth out there unless we venture out of the cave.

Lightice wrote:

I'm fairly sure that these were Plato's thoughts, not Socrates's. Ofcourse we can't know for certain, since almost everything we know about Socrates comes from Plato's writings, but the "world of ideas"-concept is usually attributed to Plato.

That always bugged me when I was reading the Socratic dialogues   I wanted to know how much of them was actual Socrates, and how much of them was Plato using Socrates as a sock puppet.  I think that's probably why I liked Aristophanes' "The Clouds" so much; I finally got a perspective on what kind of guy Socrates was from someone other than his reverent student!