Well, my criticism was maybe pedantic, and I was going too far in saying that the cogito can't be regarded as an attempted proof. My main point was about the impossibility of doubting one's existence. Of course, if you can't doubt your existence then proof is inappropriate.

Of course, if you can't doubt your existence then proof is inappropriate. — jamalrob

I don't see that. You can not doubt your own existence, but that doubt is in the empirical realm. If you speak in the completely a priori realm, then you don't exist, as physical structures don't exist there. (IN pure logic.) With, and only with, "cogito ergo sum", the two realms are connected in one fell swoop.

The proof is only inappropriate if you bind yourself to accept empirical truths. If you bind yourself only to a priori truths, then the self, which is physical, is STILL THERE.

You may argue that the self is not physical.

(1) I answer to that that in a priori logic nothing thinks.

(2) There is not a symbol in symbolic logic that means "think". And all a priori logic can be described by symbolic logic.

I am winging (1) and (2) but I am not sure that I am wrong.

So if the act of thinking is not a priori, then it's in the physical world. and therefore QED "cogito ergo sum" connects logically the only proof of anything in the physical realm to the a priori realm.

We need to take care with the direction in which the discussion goes. We started by looking at logical structures, but now we are way over at Quine's Two Dogmas of Empiricism. Happy to go there, if you like, but not until we've finished with the logical structure.

And the logical structure of Descartes' argument is not as clear as it might seem. I would have you to look at this valid argument again:

• I think
• Therefore I exist

and then at this invalid argument:

• There are thoughts
• Therefore I exist

Notice that these arguments are not of the form (A; A implies B; therefore B). They are dependent on the content of each statement. A logician would say they are not propositional but rely on predication.

Let's look closely at the premise in each case - the first line. "There are thoughts" says nothing about who is having the thoughts. Because of this, it cannot reach the conclusion that the thinker exists. TO do that it would need an addition assumption. "I think" is different. It does say who is having the thoughts.

But in saying who is having the thoughts, it is already saying that the thinker exists. It supposes the conclusion it reaches.

This should not be a surprise, since for any valid argument the conclusion has to be present in the assumptions.

Notice that the argument is not invalid; it's just that it is pretty much the same as saying "I exist; therefore I exist".

Yep.

His point was that you cannot doubt your existence. It's not the kind of thing that can be doubted. I took that to be your own point. — jamalrob

If one cannot doubt one's existence, then why would one need an argument to prove that one exists?

Descartes decided to doubt as much as he could, without good reason, and found himself stuck at not being able to doubt the doubter. Wittgenstein pointed out that doubting can only occur against a background of certainty. Something must be held firm in order for there to be any doubt.

SO the cogito is not making the same point as Wittgenstein is making. Wittgenstein is saying we don't need the cogito.

Yes, exactly.

Cheers.

Of course, if you can't doubt your existence then proof is inappropriate. — jamalrob

Yep.

You can not doubt your own existence, but that doubt is in the empirical realm. — god must be atheist

What counts as empirical is problematic. See Quine. But this is probably not the place.

Quine's Two Dogmas of Empiricism. — Banno

I don't know what the Two Dogmas of Empiricism is by Quine's. You are shortcutting the long argument, and I am not able to handle that, as I am uneducated in philosophy. This thread is also veering away from its original spirit -- a thread with reasonable thought of the dilettante, vs the short-cut referencing by highly learned individuals.

You guys say, "why prove something that you can't doubt." I can answer that easily.

What I can't doubt is not proof. It is an undoubted impression.

By proving that an impression has the proof strength of a priori truths, is a proof of an empirical truth on the a priori level. THIS is phenomenal, as this is the only proof that breaks the boundary between empirical and a priori proofs. Sort of a cross-over hit in the vernacular of the top-40 hit radio announcers.

I don't want you to get excited about this as much as I am. To me it's gold... to you it's nothing. That's fair. Each to his own. I don't like cabbage rolls, while you may not like smoked pork fat. I like cross-over proofs that prove an empirical truth on the a priori level. To you guys it's an inappropriate proof.

At this point it's not a logical argument, but an argument on personal values, and if we continue this to the extreme, we'll get into a shouting match. Therefore I withdraw from this thread, you can continue and I won't even look at it.

We can proceed at your pace, by all means. The OP made mention fo the thread on free logic, so I presented a less formal account of that argument - my previous posts here. Can you let me know what you make of them?

Looking further afield, you are concerned about the "boundary between empirical and a priori proofs"; now Quine pretty convincingly shows that there is no such boundary. If he is correct, then the Cogito is not needed for that purpose.

If you bow out, I've nothing to say here, and will return to other threads.

Cheers

It’s worth clarifying what Descartes meant by “thinking,” which he is clear about: he means consciousness. (Feelings, pains, emotions, abstractions, desires, etc.)

“I am conscious, therefore I exist.”

I see a lot of confusion about this, but it’s a crucial point. If we take “thought” in some other sense — as logic, as abstract reasoning, as conceptualization, or as internal dialogue — we’re doomed before we start.

In the strict form of the argument comes at the end of a meditation in which he attempts to doubt everything; it is "I doubt therefore I am".

I have convinced myself that there is absolutely nothing in the world, no sky, no earth, no minds, no bodies. Does it now follow that I too do not exist? No: if I convinced myself of something then I certainly existed. But there is a deceiver of supreme power and cunning who is deliberately and constantly deceiving me. In that case I too undoubtedly exist, if he is deceiving me; and let him deceive me as much as he can, he will never bring it about that I am nothing so long as I think that I am something. So after considering everything very thoroughly, I must finally conclude that this proposition, I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind.

“I am conscious, therefore I exist.” — Xtrix

...is still "I exist, therefore I exist".

If one cannot doubt one's existence, then why would one need an argument to prove that one exists?

Descartes decided to doubt as much as he could, without good reason, and found himself stuck at not being able to doubt the doubter. Wittgenstein pointed out that doubting can only occur against a background of certainty. Something must be held firm in order for there to be any doubt.

SO the cogito is not making the same point as Wittgenstein is making. Wittgenstein is saying we don't need the cogito. — Banno

That's fair, but Descartes doesn't argue that he exists; he says he cannot doubt it. This is at least part of what Sam was saying and which I pointed out that Descartes was also saying.

Otherwise, of course you're right that it was Wittgenstein, not Descartes, who showed "that doubting can only occur against a background of certainty".

I'm not sure it's right to say that Descartes tried to doubt everything without good reason, but that's a historical matter.

Descartes doesn't argue that he exists; he says he cannot doubt it. This is at least part of what Sam was saying and which I pointed out that Descartes was also saying. — jamalrob

Ah, I see. Yes, I'll go along with that.

Thanks, I'm glad I'm off the hook.

“I am conscious, therefore I exist.”
— Xtrix

...is still "I exist, therefore I exist". — Banno

You can be unconscious and still exist.

Consciousness is not synonymous with being.

Sure.

Yes he is the God of Israel he is in all things but not for us to judge.

The problem arises immediately when when you counterpose "thought" with the "physical world". One must explain why thought cannot be physical. What is it about thought specifically that prevents it from being a physical thing?

The distinction to make is between dependence and mind-independence, and the question is, are there things independent of physical minds (this is a provocation, but merited)? There are many ways to slice this question, I'll simplify to two options:

Either there is not something independent of mind or there are things independent of mind. I think there are things independent of mind, because we cannot come anywhere near close to exhausting concepts by thinking alone. And there are things we discover which we would not come up with absent empirical investigation.

But the world is a postulate, used to make sense of experience. As for God, I don't see how this helps much, unless specified some specific function.