"I think, therefore I exist" -- Rene Descartes

Philosophy, An introduction to the Art of Wondering - Sixth Edition -- pages 36/37 | 1994 | James L. Christian

[thinktwice]

Descartes was a geometrician. He found only in mathematics and geometry the certainty that he required. Therefore, he used the methods of geometry to think about the world. Now, in geometry, one begins with a search for axioms, simple undeniable truths – for example, the axiom that a straight line is the shortest distance between two points. On the foundations of such “self-evident” propositions, whole geometrical systems can be built.

Following his geometrical model, Descartes proceeds to doubt everything – de onmibus dubitandum. He will suspend belief in the knowledge he learned from childhood, all those things “which I allowed myself in youth to be persuaded without having inquired into their truth.” Doubt will be his method, a deliberate strategy for proceeding toward certainty. (Descartes is a doubter not by nature, but by necessity. What he really wants is secure understanding so he can stop doubting.)

Descartes finds that he has no trouble doubting the existence of real objects/events – our senses too easily deceive us. And we can doubt the existence of a supernatural realm of reality – figments and fantasies are too often conjured by our native imaginations. But now his geometrical model pays off: in trying to doubt everything, he discovers something that he can’t doubt. What he can’t doubt is that he is doubting. Obviously, I exist if I doubt that I exist. My doubt that I exist proves that I exist, for I have to exist to be able to doubt. Therefore I can’t doubt that I exist. Hence, there is at least one fact in the universe that is beyond doubt. “I am, I exist is necessarily true each time that I pronounce it, or that I mentally conceive it.

Descartes thus becomes the author of the most famous phrase in Western philosophy: Cognito ergo sum, or, in his original French, Je pense, donc je suis. – I think, therefore I exist. With roots in St. Augustine, this is certainly one of the catchiest ideas yet created by the human mind.

[TX Bluebonnet]

On a lighter note: I used to have a skunk under my house that I never actually saw. I knew it was there because my cat got sprayed a couple of time.

Its motto: I stink, therefore I am.

By the way, don't ever try to bathe a cat in tomato juice. Your bathroom will end up looking like a scene from "Psycho"

[discostu]

But his whole concept was working out from the only thing that didn't ever have to be proven. The position he started from was that everything around you could be an illusion, the very body you live in could be a mental construct, to put it in modern terms, we could all be in The Matrix. But he knew, with absolute certainty, that he existed because he could contemplate this in the first place. The fact that he could think proved beyond any possible doubt that somewhere somehow in some form he existed. From there he went on to prove that everything else (including God, or at least something God-like) existed. From the starting position he was going for God was one of those external "things" that he couldn't be sure of (remember, his very body was on that list, it's not that he was being anti-religious he was looking for proof of reality on it's most basic level).

It's really a very interesting logical excercise. Useless, but very interesting.

[thinktwice]

our bio-computers do not create ideas but just manifest intelligence emanating from a Source beyond our human perception.

If so, you would -- apparently -- hold that Hitler's idea to eradicate Jews emanated from a Source beyond our human perception.

[BikerNYC]

"Consciousness is a being whose existence posits its essence, and inversely it is consciousness of a being, whose essence implies its existence; that is, in which appearance lays claim to being. Being is everywhere...We must understand that this being is no other than the transphenomenal being of phenomena and not a noumenal being which is hidden behind them...It requires simply that the being of that which appears does not exist only in so far as it appears. The transphenomenal being of what exists for consciousness is itself in itself.... Consciousness is the revealed-revelation of existents, and existents appear before consciousness on the foundation of their being...Consciousness can always pass beyond the existent, not toward its being, but toward the meaning of this being. A fundamental characteristic of its transcendence is to transcend the ontic toward the ontological. The meaning of the being of the existent in so far as it reveals itself to consciousness is the phenomenon of being...This elucidation of the meaning of being is valid only for the being of the phenomenon....For being is the being of becoming and due to this fact it is beyond becoming. It is what it is. This means that by itself it can not even be what it is not...It is full positivity. It knows no otherness; it never posits itself as other-than-another-being. It can support no connection with the other. It is itself indefinitely and it exhausts itself in being...Consciousness absolutely can not derive from anything, either from another being, or from a possibility, or from a necessary law. Uncreated, without reason for being, without any connection with another being, being-in-itself is de trop for eternity." (Being and Nothingness, 1943)

[eastsider]

Descartes was trying to provide a foundation for knowledge, and the existence of God is a keystone in Descartes' foundation for knowledge. Once it's established that God exists, it then can be established that clear and distinct ideas are true because if they weren't true, God would be a deceiver.

God, then, plays this essential role in Descartes' axiomatic philosophy: God exists; God is not a deceiver; therefore, clear and distinct ideas are true.

[dyed_in_the_wool]

the very body you live in could be a mental construct, to put it in modern terms, we could all be in The Matrix.

Uh, the 'Matrix' was a ripoff of Plato's Allegory of the Cave, from The Republic. Not exactly a 'new' idea.
And many question whether Descartes ever solved his problem,or even stated it correctly.
Finally, mental exercise is a lot of things, but not useless. Unless, of course, you're in an environment where thinking is considered useless.

[discostu]

Right, but you have to build to God. If you don't "know" there's a world in the first place you can't have God the Creator. If all of everything is an illusion (not a lie necessarily, there's a difference) then so would be God. It works like all mathematical proofs, you've got to start with that which is so absolutely obviously patently true that it doesn't need tobe proven. The only thing you have absolute knowledge of is your own thoughts. You think, this is a given, this proves that you exist, from there more things can be proven. It's not until we have proven that there is a reality we live in that we can even begin to prove that said reality was made by God.

[eastsider]

The only thing you have absolute knowledge of is your own thoughts. You think, this is a given, this proves that you exist, from there more things can be proven. It's not until we have proven that there is a reality we live in that we can even begin to prove that said reality was made by God.

The only reality Descartes needed to "prove" was his own existence. Once he did that, then he went on to "prove" the existence of God via the ontological argument. If both Descartes' existence and God's existence could proven, the rest of reality (i.e., everything other than Descartes) would necessarily exist because God is not a deceiver.

[discostu]

Not only that, it was a rip-off of a really good Twilight Zone episode. ;)

I never said Matrix was new, actually I think Matrix kind of sucked, a good looking but incredibly stupid movie. I was drawing a parallel to help illustrate for people. Neo runs into a situation that was basically what Descartes was working with as a thought experiment: the idea that the only thing truly "real" was his own thoughts, that indeed he existed but nothing else that he'd thought of as reality actually did. The problem with the Matrix is that Neo is effectively god in that illusionary reality, and he got to find out what was really real and it totally sucked, and he chose to break the machine anyway. No person faced with that situation would do what he did, there's no reason for it, thus everything after that decision was just dumb. And as an audience member my temporary suspension of disbelief was terminally shattered never to come back... but the special effects were really cool. Great movie to watch with the sound off.

Different concept of useless. The end result of Descarte's thought experiment was really nothing, he wound up back where he started, that indeed reality was real. While yes mental exercise is good, this particular mental exercise was no more innately useful than any other. It accomplished nothing, but it's fun to work with. People shouldn't be so uptight about the word useless, there's lots of useless things in this world that I wouldn't give up for anything. They serve no real purpose, but they're fun so what the heck.

[thinktwice]

It's not until we have proven that there is a reality we live in

If your existence is a proven fact, that fact is a truth within the self-same reality ... that you don't seem to know exists.

"Truth is the recognition of reality." -- Ayn Rand

[diotima]

Some have argued, like Hintikka, that cogito ergo sum is "demonstrated" because it is meant to be a performative assertion: the act of its assertion is, via performance, its truth. Along the same lines cogito ergo sum can also be translated as "I am thinking, therefore I am."

I always liked the second meditation the best.

[discostu]

But at the point in the proof when Descartes had proven his existence that existence had no form or function. Whether he had a physical body that lived in a physical world with other people and animals and plants and cool stuff like that, or was nothing more than a bored electrical impulse bouncing around a void that had gone bonkers and had made up all this other stuff, had not yet been decided. You can't jump from that point straight to God, not from a position of pure mathimatical logic anyway. Remember this isn't an exercise in faith, it's an exercise in pure mean spirited logic that starts off by denying EVERYTHING, from the existence of God down to that annoying little hangnail, then seeing how much of it you can rebuild with pure logic and reasoning. As it turns out you can put EVERYTHING back with logic... unfortunately that includes the hangnail.

[Katya]

"Cogito ergo Freeperum.

My husband is making up a sign later to support Ehrlich and other fellow republicans: Would this be correct:
cogito ergo Republicanum

[thinktwice]

As it turns out you can put EVERYTHING back with logic

With, of course, mystical beliefs and things not true excluded.

[Aquinasfan]

"Truth is the recognition of reality." -- Ayn Rand

Could she explain how the ideas in her head corresponded with an external reality?

If her mind was strictly material, how could she know with certainty whether or not it was malfunctioning?

Truth is the adequation of mind and reality.

[savedbygrace]

"I think. Therefore I exist."

Unnecessarily long. Can be: "I. Therefore I exist." Having a concept of I proves thinking has taken place, so it is not necessary to add the argument "think."

[discostu]

But how do you know it's real? How do you know you're really sitting in front of a computer reading FR and not just some looney having a very long dream?

[discostu]

Descartes was more focused on things like trees, deciding if they were even real in the first place.

[eastsider]

You can't jump from that point straight to God, not from a position of pure mathimatical logic anyway.

In Descartes' mind, the jump from his own existence to the existence of God was possible because the ontological argument for God (the Fifth Meditation) is, as its name implies, based on existence. Descartes claims he can prove the existence of God merely from the idea of God. And that's what the ontological argument purports to do.

What makes Descartes' argument peculiar is that it takes as a premise the idea of a perfect being. Descartes' cogito argument leads to the conclusion that all of the ideas that we find in our minds exist as ideas in our mind, and the evil demon can't deceive us about that. Any idea that I find in my mind, I know to exist as an idea in my mind. So if I have the idea of a perfect being, I know that that exists as an idea.

The question is, does the idea of a perfect being correspond to anything outside me? For example, using my idea of a desk, I can ask whether the idea of a desk corresponds to anything outside me. There seems to be a desk; does that 'seeming' to be a desk correspond to anything real outside me? And you can ask the same question about the idea of perfect being. Does that correspond to a real perfect being outside me?

Descartes argues that all we have to do is to think of this idea of a perfect thing, to analyze this idea, and we'll come to see that such a being necessarily exists. That is, he argues from the idea of such a being to the necessary existence of such a being.

[Hillarys Gate Cult]

I'm surprised that no one has posted "The Philosophers Song" yet.

Do you mean this?
http://library.adelaide.edu.au/guide/hum/philosophy/philos_song.html