I was wondering, if "I exist" sole on the basis of thinking (all realms of thinking), how would I know that I'm think or what if something is controlling my thinking. When I sleep, it's scientifically proven that my body has autonomic processes for breathing, and other processes (or sleep walking for other people). How can I prove that I, in fact, am thinking? *In regards to Renes Descartes' Meditations 2. — dakota

You "prove" you are thinking by acting like a thinking person does. I guess it's like the Turing test - From Wikipedia:

The Turing test, developed by Alan Turing in 1950, is a test of a machine's ability to exhibit intelligent behavior equivalent to, or indistinguishable from, that of a human. Turing proposed that a human evaluator would judge natural language conversations between a human and a machine designed to generate human-like responses. The evaluator would be aware that one of the two partners in conversation is a machine, and all participants would be separated from one another. The conversation would be limited to a text-only channel such as a computer keyboard and screen so the result would not depend on the machine's ability to render words as speech.[2] If the evaluator cannot reliably tell the machine from the human, the machine is said to have passed the test.

...how would I know... — dakota

At some point the boundary of knowledge is just axioms and presuppositions. To escape from the possibility of an infinite cascade of, "How do I know (that I know (that I know...)...)... you take a different tack. For example, define "know/knowing"; assume that you know, and attempt to find a contradiction, or confirmation. In this sense I would call all knowing, knowing in consequence of....

Maybe I should stay out of this thread, because I've never read Descartes myself, but here's a reply based on what I've read about this:

• Thinking isn't the basis of your existence. It's the only thing you can't doubt (and that makes sense to me, since doubting is also a form of thinking: if you don't think you don't doubt, and there's no problem left to discuss - not that that's any sort of argument; it's just a good place to stop.)
  
• You don't prove that you're thinking, you just intuit it. And unlike many other things you intuit, you can't doubt it away. (If you can, I'm immensly curious to learn how.)
  
• It doesn't matter whether or not anyone controls your thinking. If you're not thinking there's nothing to control. I always sort of assumed this was about direct experience, and about thought in particular because radically doubting things is a thought process.

Again, this comes from someone who's never read Descartes, so take this post in accordingly.

You cannot prove an "I" exist merely by thinking for a wide variety of reasons, but one would come from modern neuroscience. Because the brain is modular there is simply no "I" involved.

You are directly aquainted with the fact that you are thinking. It is right there before your mind, and when something is before the mind in this way, there is just nothing more you could want by way of proof. You consider whether it is possible that someone is controlling your thinking. It is possible, but it follows from that hypothesis that you are thinking! Otherwise, whose thoughts are being controlled?

I do not think that Descartes intended to infer deductively that he exists from "I think". He says as much in his replies to critics. Rather, that you exist is presupposed by the possibility that you might be mistaken. If you are mistaken, then you exist. Hence it is not logically possible that you are mistaken that you exist.

You are directly aquainted with the fact that you are thinking. It is right there before your mind, and when something is before the mind in this way, there is just nothing more you could want by way of proof. — PossibleAaran

But if it is 'before your mind' then you are not directly acquainted with it. We would have two separate things, subject (your mind) and object (your thought). 'Consciousness' would then just be another object of perception and we certainly can doubt any object of perception. Or if we can't, why wouldn't it apply equally to any object before our mind? 'I see a doughnut, therefore I exist'.

It only seems to work because 'consciousness' seems to be a ghostly immaterial thing, like 'mind'. But really I am never 'conscious of consciousness', just as I never 'think of thinking'. In practice I am always conscious-of some thing, I am always thinking-of some thing.

To conclude from 'I think' that 'I exist' is no more than to say that a verb must have a subject, but it doesn't explain what is meant by that 'I'. For example, it my be that Descartes is newly created moment by moment, so that the 'I' has no continuity. It might be that the 'I' is not Descartes but a demon who places each thought in Descartes head. Descartes may have no material existence - there may be no material world at all. For Descartes to conclude he is Descartes - a man, rational, continuous and so on - needs a different set of arguments.

Some suggest that 'I think, I am' is a performative truth that is epistemically valid only when it is thought.

Hi, . Nice to meet you.

But if it is 'before your mind' then you are not directly acquainted with it. We would have two separate things, subject (your mind) and object (your thought). 'Consciousness' would then just be another object of perception and we certainly can doubt any object of perception. Or if we can't, why wouldn't it apply equally to any object before our mind? 'I see a doughnut, therefore I exist'. — Londoner

I did not intend to say that I am ever directly acquainted with consciousness (I think that I am, but it isn't part of my argument that I am). I meant to say that I am directly acquainted with a particular thought of mine. For instance, I can be acquainted with my thought "The bacon smells good", simply because the thought passes right through my conscious awareness. This is how one knows that one is thinking - by being directly acquainted with particular thoughts. It is true that in this act of acquaintance there are two relata - the subject (me) and the object (my thought), but I don't see why you would infer from this that I am not directly acquainted with my thoughts. You say that "we can certainly doubt any object of perception". I am not sure about this. Many philosophers think that it makes sense to doubt a proposition like "there is a doughnut", when you see one. I am not sure that it does, but I leave that aside. I would insist, however, that when you are acquainted with the thought "the bacon smells good", it makes no sense to doubt that you are thinking that thought. The thought is present to your mind in such a way as to make the suggestion that you are not having that thought unintelligible.

In practice I am always conscious-of some thing, I am always thinking-of some thing. — Londoner

Indeed, and that is how I know that I am thinking.

To conclude from 'I think' that 'I exist' — Londoner

As I rendered the Cogito, it doesn't involve inferring "I exist" from "I think". My position was that "I exist" is a proposition which it is logically impossible for me to be mistaken about (this is what Descartes is getting at when he says that "I exist" is necessarily true whenever it is entertained in my mind). I agree with your last point that this does not yet establish that the person who I am now is the same person as the person from one second ago, or even that there was such a person one second ago.

It seems to me that we are begging the question, as does the formulation 'I think therefore I am'.

What sort of argument is that? Plainly, the conclusion is entailed in the premise! So is the bit after 'therefore' telling us something new? Is 'I am' something more than 'this thought'? If it is, we need something more, some additional premise. Or is it only saying 'I' is synonymous with 'this thought'?

Because, if it is only meant as a synonym, that 'I' seems to quickly take on extra meanings. For example, we shift to talking of 'consciousness', something that is distinct to the 'thought' , we have 'awareness', we have 'particular thoughts', all of which are assuming notions of perception, of personal continuity through time, that were not there in the single original 'a thought'.

If we remember that the object of the exercise is the 'I am' bit, then the problem with saying: when you are acquainted with the thought "the bacon smells good", it makes no sense to doubt that you are thinking that thought is that it doesn't explain what is meant by that 'you'. Indeed, there is no need for a 'you' to be involved at all, that reaction to the bacon need be no different in kind to a chemical reaction, where we find no need to posit that there is a 'you' within each chemical that is 'having' that reaction. Or, if we did extend 'you' to such things, that is not the sort of 'you' we were trying to get to, the one with 'consciousness'.

I think it only works the other way round. We must start from 'I am'. How do I know I am? I just do; I have no choice. If I say things like 'I think' it is only because it is founded on an already existing sense of myself, as something that does things. As I say at the beginning; 'I think...' is predicated on that 'I', there can be no 'think' without an 'I', so the 'I' cannot be the conclusion.

If you can doubt whether you are thinking, then you are thinking. Doubt is a kind of thinking. That's why the argument is said to be based on 'Cartesian doubt'.

If you can doubt whether you are doubting, then you are again thinking.

Even if you're neither thinking nor doubting, to the extent that (let's suppose) your thoughts and doubts are controlled by an outside force, then Descartes' main argument applies. "My thoughts are controlled by an outside force, therefore I exist."

Gassendi pointed out to Descartes that 'I walk, therefore I am' is an equally valid argument.

If we remember that the object of the exercise is the 'I am' bit, then the problem with saying: when you are acquainted with the thought "the bacon smells good", it makes no sense to doubt that you are thinking that thought is that it doesn't explain what is meant by that 'you'. Indeed, there is no need for a 'you' to be involved at all, that reaction to the bacon need be no different in kind to a chemical reaction, where we find no need to posit that there is a 'you' within each chemical that is 'having' that reaction. Or, if we did extend 'you' to such things, that is not the sort of 'you' we were trying to get to, the one with 'consciousness'.

I think it only works the other way round. We must start from 'I am'. How do I know I am? I just do; I have no choice. If I say things like 'I think' it is only because it is founded on an already existing sense of myself, as something that does things. As I say at the beginning; 'I think...' is predicated on that 'I', there can be no 'think' without an 'I', so the 'I' cannot be the conclusion. — Londoner

Are you familiar with Hume's thoughts on the self? Or Sartre's on consciousness and intentionality? If they aren't already familiar to you, then you might like them, since some of the things you are saying remind me of ideas they also wrote about.

I would focus personally on the leap from the use of a single word to the assumption that it is connected to some entity. We use the word 'I' according to mostly unwritten rules. It has something like a cloud of meaning. When we try to be strictly logical with cloudy words, it's not surprising that we don't come to a consensus. On the other hand, we always already 'believe' in the ordinary language that we use to build philosophical systems in the first place, in the sense that we use ordlang without first examining it in order to examine it, in order to double back and question it. So ordlang has a kind of blind knowhow that can double back on itself to illuminate this or that aspect of itself, doing so by taking the rest of itself for granted, one might say.

For me this means that certain philosophers are only attempting to construct false foundations that aren't really propping anything up. In this case, a person could only want to prove that they were thinking if they were using the words in an extraordinary way. They are free to do so, and it may even pay off, but I think the rule is the same old arguments that go nowhere.

It seems to me that we are begging the question, as does the formulation 'I think therefore I am'.

What sort of argument is that? Plainly, the conclusion is entailed in the premise! So is the bit after 'therefore' telling us something new? Is 'I am' something more than 'this thought'? If it is, we need something more, some additional premise. Or is it only saying 'I' is synonymous with 'this thought'? — Londoner

When does an argument beg the question? It can't be just when the premise entails the conclusion, for then every deductive argument will be question begging and we will have to say that deduction is always unacceptable. Normally, philosophers say that an argument is question begging when the conclusion itself is the reason cited in support of the premise. The Cogito isn't like that. The premise, "I think" is supported by direct acquaintance. I am directly acquainted with the fact that I am thinking. Hence, the premise is not defended by appeal to the conclusion.

I expect you will be unhappy with this. You object:

Because, if it is only meant as a synonym, that 'I' seems to quickly take on extra meanings. For example, we shift to talking of 'consciousness', something that is distinct to the 'thought' , we have 'awareness', we have 'particular thoughts', all of which are assuming notions of perception, of personal continuity through time, that were not there in the single original 'a thought'. — Londoner

I don't think any of this is right. When I am directly acquainted with the thought "the bacon smells good", what this establishes is that there is a thought; whether or not it is mine is a further question. But what drives us to the further claim that "I am thinking" is that scepticism itself presupposes a subject. Scepticism is only an issue if it is possible that my beliefs might be mistaken, but if there is no "me" then there is no such thing as "my" beliefs and ipso facto no possibility of my beliefs being mistaken. Either I exist and am not mistaken that I exist, or I don't exist and (obviously) am not mistaken that I exist. I can't be mistaken that I exist. I have not here used the word "consciousness" or assumed continuity through time, as you say that the cogito must.

Indeed, there is no need for a 'you' to be involved at all, that reaction to the bacon need be no different in kind to a chemical reaction, where we find no need to posit that there is a 'you' within each chemical that is 'having' that reaction. Or, if we did extend 'you' to such things, that is not the sort of 'you' we were trying to get to, the one with 'consciousness'. — Londoner

I deny that thoughts are just chemical reactions, but that is really besides the point. Whether a thought is a chemical or not, that I exist is a preupposition of scepticism. That is why it is posited. If you don't like talking of consciousness and you like talk of chemical reactions, I think you miss something very important, but it doesn't really matter for this argument. For all that has been said, I might just be a mass of chemicals and lumps of flesh, but what is certain is that I, whatever I am, exist.

PossibleAaran

Yes, I would say that a deductive argument, in the sense of one where the premise entails the conclusion, isn't any use if we are making an assertion about what exists.

I would not agree that 'The premise, "I think" is supported by direct acquaintance'. If I am acquainted with something, then two things are involved; me and the thing. In that case, the thought is not purely an object to me, nor am I identical with the thought. Like any object of perception we cannot say where the perceiver leaves off and the thing perceived begins, (if indeed either side exists at all).

As I say, the object of the exercise is not to show the thing, the thought, exists, but to show the thinker exists in the sense of being a consciousness, so in order to do that the consciousness must be distinguishable from the thought. If the two were directly acquainted in the sense of being one and the same thing, we would not have done this.

You write that 'scepticism itself presupposes a subject'. I would say that it rather makes the notion of a 'subject' meaningless because the word 'subject' is only understood relative to 'object' and skepticism denies there are objects.

But one does not have to be a skeptic to do this. We can give an entirely materialist account of human existence. (Just as we can give an entirely idealist one). Or we can suggest a mixture. But there is no way we can examine a particular perception and discover which account is correct.

I would say there is a similar problem with the claim that 'I exist'. I do not understand what that means; i cannot just exist, I have to exist as something. For example, I might say 'this stone exists' and mean it can be sensed. I might say 'that dream existed' meaning I am telling the truth about an experience I had, and so on. But I cannot understand 'exist' on its own, without a context.

So does 'the thought' exist? Exist in exactly the same sense that the 'I' that it is supposed to prove exists? That cannot be the case if 'the thought' is an object to the subject that is the 'I', (but not the other way round). So, if the sense in which 'the thought' exists is different to the sense in which 'I exist', so we cannot use one to prove the existence of the other.

mrcoffee has correctly identified what I have been reading lately, along with Merleau Ponty (how's that for a name-drop!). Hence my desire to test some of it out here.

OK, so here's the difference between perceiving and thinking: You perceive when your sensory organs impulses creates mind images, on the other hand, thinking is about to construct mind images without the five senses and organize them as you want. So, a way to prove to someone else that you're thinking could be guessing what this other person is thinking of and how the person thought about it.
For example, if you show to the person a fish tail and a woman and ask him to imagine a creature, it would probably be a mermaid. Of course this was a foolish example, but if you ask something more difficult, with ambiguous answers and explain how to conclude, proving that you are aware of the process,I guess that it's' a good proof.

A mistake people are making about Descartes (it seems to me) in much of the discussion so far is that he took his cogito to be a deductive argument. We all know the expression "I think therefore I am" but that formulation is NOT the one to be found in the Second Meditation. There it is just stated "I am,exist" and is not (somewhat misleadingly) dressed up as a premise and conclusion. Descartes' point (whether you agree with him in the end or not) is that there are some propositions that do not require proof, they simply wear their truth on their sleeves, so to speak. His idea was that the entire edifice of science can then be constructed on the basis of those bedrock propositions (plus the rules of inference, of course). He may not be right about that, but he certainly wasn't wrong in the way some people on here seem to be suggesting.

"Thinking" is just the name of that thing you're doing, and being a naming convention it's not a thing for proving.

The idea of the cogito as I understand it is that "I am a thinking/experiencing thing" is indubitable because even in the extremity of doubting that idea, one is thinking, because doubt is itself a form of thought/experience.

"I think, I am" is therefore true apriori, without having to consult experience or the content of thought.

Where this leaves us, essentially, is that we can be absolutely certain of what we're saying, so long as we prefix everything with "it seems to me" or "I am having the experience now of ..."

IOW, regardless of whether anything is some particular way, we can be certain that things seem to us to be that way.

how would I know that I'm think or what if something is controlling my thinking. — dakota

It doesn't matter. You're the one experiencing the thought, and that's the relevant part. You can prove the existence of the experience to yourself by experiencing it.

I was wondering, if "I exist" sole on the basis of thinking (all realms of thinking), how would I know that I'm think or what if something is controlling my thinking. — dakota

What would be a good reason to believe that "something is controlling" your thinking? Just because something is possible doesn't mean that's a good reason to believe it's true.

Also, we have very good reasons to believe that thinking beings (like humans) exist. It would be incoherent to believe that something that thinks does not exist, since thinking is an existent state.

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