Ok. Well I hope you can find out one way or another if you are. — flannel jesus

LOL I really hope I'm not!!!!

I hope so too brother.

I hope so too brother. — flannel jesus

I did have a cream cake last night at 10.30pm. That does seem a bit devilish :grimace:

Have some angel cake tonight, you'll be alright.

As for me, I don't mind. My favourite picnic food is deviled eggs.

Have some angel cake tonight, you'll be alright — flannel jesus

Oh my gosh! I am not kidding, I have some angel cakes in my cupboard! How spooky! (I just spent ages trying to figure out how to post a picture ive just taken of them, but I couldn't figure it out, so I put it as my profile picture lol)

Watch out for those deviled eggs!

You have: — Lionino

You keep doing this. I ask for a demonstration that "Whatever thinks, exists", and you reply with a demonstration that if "Whatever thinks, exists" then I exist:

Whatever thinks, exists.
I think.
I exist. — Lionino

I am after a proof of the first line. The syllogism is not a proof of the first line of the syllogism.

I seem to have to keep making this point, and I am not enjoying doing so.

The crux is that we may doubt that anything is pink, but we cannot doubt that we think, because when we doubt that we doubt, we are doubting, and doubting is a type of thinking — and that is self-evident aka clear and distinct. — Lionino

This is more to the case. But there is a problem here, in the move from a variable to an individual...

U(x)(Px ⊃ ∃(y)(x=y))

to

Pa

For clarity, let's move to free logic, adopting the definition ∃!a = ∃(x)(x=a).
What Descartes wanted was

U(x)(Px ⊃ ∃!x)
Pa
⊢∃!a

(edited) But again, this is invalid. It needs the additional deduction Pa ⊃ ∃!a, which requires ∃!a.

That is, the argument does not lead to the conclusion that I think - that individual. All it concludes is that something thinks - whatever is the referent of the variable x.

This is I take it the point Russell makes, probably set out a bit more formally than he was able to do with the state of logic in his time.

On Tuesdays and Thursdays...

It seems like it:

But this just says that if some individual has a property, then there is an individual. It works not just for thinking but for being pink. For all x, if x is pink then there is something that is pink.
— Banno — Lionino

There is a difference between concluding that a particular individual is pink - "Fred is pink" - and concluding that something is pink - "x is pink" .

That's why we differentiate Px and Pa in first order logic.

There is a reason 90% of all people 10 years old or more think “I think therefore I am” is a stupid argument. It’s not because of the logic; it’s because what it is trying to argue is so obvious. Everyone already knows “I am” - and they rightly think that if you needed a proof to conclude you exist you might be an idiot. — Fire Ologist

Quite right.

In so far as I have a purpose here, it is to show how silly it is to rely on "I think, therefore I am".

To that end, I have been at pains to show that a certain syllogism does not show that "I think, therefore I am" is true; and that "I think, therefore I am" is not the result of an inference but is rather closer to an intuition.

It would be extraordinary if mere logic were to conclude that this or that thing exists. That is not the sort of thing logic is capable of.

"I am" does not need "I think" as a preamble.

From a related thread...

Think of free logic as an attempt to make explicit the logical structure of such existential arguments by making explicit the first order existential predicate E!a - "a exists", where a is a proper name; so an example would be "MadFool Exists".

And what this explication found is that it cannot deduce that MadFool exists. All it can do is presuppose it, by assuming that MadFool is a part of the domain of E!x.

Put anther way, in trying to show the validity of "I think therefore I exist" it instead shows that it is circular, that "I think" already supposes that "I exist".

Descartes' argument is valid, but circular. — Banno

The Madfool was a now-banned individual.

It might be better to say that If Descartes' argument is valid, then it is circular.

A good rule of thumb might be that if your logic appears to demonstrate that some particular individual thing must exist, then there is an error in your logic.

It would be extraordinary if mere logic were to conclude that this or that thing exists. That is nto the sort of thing logic is capable of.

I've got a book for you...


(Granted, it would make more sense if it was the Logic)

Thanks - Hegel as a case in point.

...there is an error in your logic. — Banno

You keep doing this. I ask for a demonstration that "Whatever thinks, exists", and you reply with a demonstration that if "Whatever thinks, exists" then I exist: — Banno

This is the first time you ask for a demonstration of that specific premise. The rest of the time you were asking for Descartes' argument as an inference. Even then, I preemptively addressed the first premise multiple times:

It relies on intuitions, like any argument does. An intuition is a belief that is not proven by inference or by experiment. Descartes is not worried to try to prove everything, he uses hyperbolic doubt, not unbounded doubt, so he does not doubt things that could not be otherwise (something thinking but not existing, or 2+2=4). — Lionino

As I said, Descartes uses hyperbolic doubt, not unbounded doubt — Lionino

The first premise is an intuition — Lionino

Is that enough for the first premise?

I know that this is a major aspect of philosophy and, if any of us could know with absolute certainty it would make so much in life simple. Perhaps, it would be too simple as if 'answers' to the biggest questions and existential dilemmas of life could be found, as looking for answers from the 'heavens' or authoritative guides and guidelines, as definitive absolutes.

It also leads me to think about how I hesitated in answers in primary school, wishing to be 'certain' of answers before volunteering answers at school. It raises the whole issue of doubt and how the spectrum of doubt and certainty exist in life and so many questions of philosophy.

I also wonder about the extent to which doubt and certainty are desired. Would I like all the answers to personal life and the existential questions of life to appear in the clouds as absolutes, Or, would it shortcut the philosophy quest, and the whole phenomenon of knowing and unknowing? T
To what extent is 'unknowing' the important variable for all philosophical exploration and innovation?

This is the first time you ask for a demonstration of that specific premise. — Lionino

Well, no, but I won't do chapter and verse. See, you took over an argument from someone else - where they were claiming that to be the whole of the Cogito. And so I at first presumed you were also claiming it to be the whole thing.

I hope we are now agreed that

Whatever thinks, exists.
I think.
I exist

is a furphy.

Let's look at "Whatever thinks, exists".

I'm making the point that it does not parse validly (is not a tautology) in first order logic anymore than in propositional logic.

Do you agree?

Do you agree? — Banno

"Whatever thinks, exists" is not a tautology, yes.

Is that enough for the first premise? — Lionino

Is that it is an intuition enough for it to be 100% certain? Folk are 100% certain about all sorts of things.

Is it enough for it to be known with 100% certainty? Well, what justification is there for this intuition?

Thanks for your patience.

Is that it is an intuition enough for it to be 100% certain? Folk are 100% certain about all sorts of things. — Banno

If you mean it with "100% certain", Descartes' achievement is not immune to silly doubts like "Do I really know what 'is' means?". In any case, no one can convince oneself that one does not exist.
You may not remember, but some 15 pages ago, our roles were switched here, and I was defending skepticism.

Is it enough for it to be known with 100% certainty? Well, what justification is there for this intuition? — Banno

Using Bayes theorem, everything that relies on something else is already not 100%.

Thanks for your patience. — Banno

To be clear, I agree that the intuition is not logically valid just like p→q is not valid. Not that it is furphy, whatever that means.

Here's a list of your replies to me.

SO, if we go back to the beginning, I gather you were being ironic.

Again, I find myself puzzling as to what we might be disagreeing about.

There is a reason 90% of all people 10 years old or more think “I think therefore I am” is a stupid argument. It’s not because of the logic; it’s because what it is trying to argue is so obvious. Everyone already knows “I am” - and they rightly think that if you needed a proof to conclude you exist you might be an idiot. — Fire Ologist

Agreed. :up:

f you think the cogito illogical and doesn’t show anything at all, you miss the point, — Fire Ologist

You still need to give some merit to Cogito. It is undeniable that it is a historical byproduct of ideas, which made start for the new philosophical tradition based on the method of doubt.

Supporting Cogito blindly as if it is a logical statement like some twidledee twiddledum folks in this thread would make them sound asinine.

However totally ignoring and rejecting Cogito as useless, and claiming, therefore it is not even worthwhile to discuss about it would make the interlocutor appear to be obtuse.

Here's a list of your replies to me. — Banno

Well, yes, in the first four I am defending skepticism.

SO, if we go back to the beginning, I gather you were being ironic. — Banno

No, I would still defend skepticism. The fact that I have to defend Descartes against improper criticism has nothing to do with that.

We are taking a real, visceral, present moment, a simple obvious moment like reading these words right now, as I am here writing these words “words” right now, this very second where “I am” needs no explanation, a momentum like this, and then we are trying to make a formulaic logical expression to re-capture this moment and codify a logical explanation on top of it. — Fire Ologist

I think the "problem" with Descarte's thought experiment is the "I". There are likely a few reasons but I'll focus on one. The problem of Time.

You are correct about his conclusion fitting the present. But this "I" which "is," is not the same "I" as the "I" which was nanoseconds ago thinking. The "I" is successive. Just as there isnt really a linear narrative, there are only successive nows.

Descarte's discovery was really "thinking therefore is-ing,." It does not rest thus no "am"; it does not rest thus no "I".

You are correct about his conclusion fitting the present. But this "I" which "is," is not the same "I" as the "I" which was nanoseconds ago thinking. The "I" is successive. Just as there isnt really a linear narrative, there are only successive nows. — ENOAH

Interesting point. I wouldn't describe Cogito as some insane moronic babble. But it is obvious that it has many rational incongruities to be classed as a logical statement. It is a subjective psychological expression at best, which reminds us to use method of doubt in all reasonings.

But it is obvious that it has many rational incongruity to be classed as a logical statement. — Corvus

But you agree with the fundamental premise of it, which is that one must exist in order to think.

Descarte's discovery was really "thinking therefore is-ing,." It does not rest thus no "am"; it does not rest thus no "I". — ENOAH

I totally agree. Or should say “agreeing is”.

Ha! :up:

:up:

one must exist in order to think. — flannel jesus

Query: why not thinking is existing in the present; beyond that, "I" and "one" is constructed to suit logic/meaning?

I'm not disagreeing. I'm wondering.

I've expressed earlier in the thread that I have a lot of sympathy for the view that "I think therefore I am" maybe should be reworded in such a way to remove the ego, to remove the I. If you feel like it makes more sense to say "There is thought, therefore something exists" or whatever, I think there's wisdom in that.

:up: