Ryle — Banno

Never heard of.

that you cite folk who reject dualism, but apparently in its defence — Banno

I am not defending dualism, but only that it appears that physicalism will always be incomplete.

Is your claim that there are two substances, or that Descartes said there were two substances? — Banno

Latter. Even for Descartes I don't thik he would say prima facie it is sure that there are two substances. The existence of bodies, aka res extensa, is far from certain. If he did, and he likely would, he would do so by invoking God.

Is that roughly what you would argue? — Banno

I am not in line with everything in the post but the last line, yes, I am at least that which doubts.

But what sort of thing? I have just now said it, a thinking thing. But am I nothing besides?

And is dualism always the consequence here? — Banno

Yes, but we can't do much against that. The hard problem of consciousness is perhaps incontrovertible.
Many physicalist philosophers say:

Image from Dr. Bogardus

Lionino is that what you meant by an impression? — Metaphyzik

An immediate awareness, an experience. This is the experience that the philosophers above are talking about. That thinking presupposes existence is an intuition, a belief that does not come from inference or from experience but that we can't conceive otherwise.

At this point my preferred quote is

What is unusual is that Corvus has been around for so long without being banned. — Banno

B∨¬A ↔ ¬B→¬A = ¬A -> ¬B ? — Corvus

No.

What do you think it means? — Corvus

I don't think it means anything. I know what it means. And it is not what you were thinking.

I think that's a fantastic example of implication to look at. — flannel jesus

I have tried that a thousand times already with "If it rains, the floor is wet". Banno also. It is pointless.

Further conversation becomes like a child hitting the dog's cage with a stick. It will bark and growl back at you; fun, but progress will not be made. — Banno

The positivists were right. Philosophy is nonsense. We should all learn coding instead.

When I asked you about the If Red Light then Drive logic for your agree or disagreement on it, you said it was order, not Logic — Corvus

Yes, "drive away if there is a red light" is an order (drive away) with a conditional (if there is), it has nothing to do with statements of the type p→q. It is a bad example. Choose another one.

Well, I was replying to your question if my newfound knowledge :zip: but from your reply I know what to take from it.

I have asked you first, but you never answered my question — Corvus

Wow, so on top of not having ever read Descartes and feeling the gaul to comment on it, on top of not knowing how to use logic, you also don't know how time works? If you scroll up, you will see I requested that you translate my phrase before you deflected with that "question" of yours.

Is it a valid inference, on which we must all agree, or is it an intuition, a mere hunch or impression? — Banno

So, from the Principles and the Replies to the Objections, to put in this exact terms, if I understand what is meant by them, the fact through which we realise we exist is an impression¹. When we express the impression, it is an inference – an enthytema often—, this reference of course relies on intuitions².

1:

But when we notice that we are thinking things, there is a certain first notion, which is concluded from no syllogism; nor even when someone says, I think, therefore I am, or I exist, he deduces existence from thought by a syllogism, but recognizes it as a thing known in itself by the simple observation of the mind, as is evident from the fact that, if he deduced it by a syllogism, he must first have known this greater , everything that thinks is or exists; but surely rather he learns himself, from what he experiences with himself, that it cannot be as he thinks unless he exists. — Replies

2:

I was not denying that we must first know what is meant by thought, existence, certainty; again, we must know such things as that it is impossible for that which is thinking to be non-existent; but I thought it needless to enumerate these notions, for they are of the greatest simplicity, and by themselves they can give us no knowledge that anything exists — Principles

It's totally understandable to go to the original French, but it really ought not to matter — flannel jesus

True.

and no one has set the inference out for us in a valid way. — Banno

:roll:

I wonder why you chose Korean specifically. But take a look at this https://thephilosophyforum.com/discussion/comment/857740

So you think of the Cogito as a poem, and are not convinced by it, but by the argument you find in it? — Banno

Descartes' arguments are a meditation. The meditation is expressed with words on a piece of paper. But it is not the words on a piece of paper — a poem —, put together validly with logical connectives in the form of English conjuctions, that prove my existence. It is when I exercise the meditation myself that I realise that I exist.

“Am thinking” says enough. — Fire Ologist

Indeed, Fire, he says in the beginning of the Second Meditation:

Wherefore I may lay this down as a Principle, that whenever this sentence I am, I exist, is spoken or thought of by Me, ’tis necessarily True.

And this article reaffirms it:

Finally, at the end of the paragraph he mentions the conclusion to be drawn when I think that I am something, namely, "I am, I exist, is necessarily true each time that I pronounce it, or that I mentally conceive it." Such a conclusion is in effect a gloss on Descartes' own use of "ergo" and once again reference to the mode of thought has appeared twice. — Descartes, Russell, Hintikka and the Self

It is, on the contrary, or so Descartes would have it, in thinking and the certainty about itself that it entails that I at the same time become fully conscious and by the same token certain of my own existence as opposed merely to acquiescing in it more or less automatically even when I seem to be calling it into question.

In a letter to Bourdin, Descartes instead puts it as "ego cogitans existo". It is not so much that we take "I think" and then conclude "I exist", but every thought gives the certainty of existence. Which is why Descartes says, as quoted by Banno, that it is almost as if he would stop existing if he stopped thinking.

My overall impression is that logic is not a strong point hereabouts. — Banno

There are not many strong points in this thread.

they do if they are by definition thinking things. That's rather the point — Banno

Which I acquisced and clarified before, you say so:

you went into great lengths about the difference between extended substance and cognitive substance, but having to invoke dualism to solve this issue counts against the whole enterprise — Banno

I would hardly say that was a great length, but the proof of one's own existence does not depend on dualism. The mind-body dualism simply clarifies under what conditions something would cease to exist when it is not thinking. If something inherently thinks, it would not be anymore if it stops thinking. If X is inherently red, X would cease to exist were it to stop being red, aka it would stop being.

In particular, the bit where you stop existing when you go to sleep. — Banno

If we define dreaming as thinking too — which is an assumption that "stop existing when you stop thinking" relies on —, we don't stop existing when we go to sleep. Even if it were, there is a difference between ontology and epistemology. Descartes is trying to show how we can come to know that we exist, which is a different matter of under what conditions we exist. That I know that «I am» is different from «what it is that I am». He explores this also in the beginning of the Second Meditation:

Let me ask therefore what I am, a thinking thing, but what is that?

You mistook me for some other folks in the thread. — Corvus

Guilty as charged ¯\_(ツ)_/¯

Sure, something is doing the thinking — Banno

Unless I know it is me, I can't say it is thinking, as I only have access to my own thoughts, not anyone else's.

When we conclude that that thought isn't ours and we only have a memory of it, we can no longer conclude that anything exists, as that memory is no proof of anything thinking; if anything, it is proof that I exist, because I am remembering it, and remembering is thinking. — Lionino

why did you laugh at the suggestion from Corvus that you cease to exist when not thinking? — Banno

Because things don't cease to exist when they don't think. And his suggestion was based on denying the antecedent, which is bunk.

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.

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.

Do you agree? — Banno

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

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?

He agreed with A1? — flannel jesus

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

"I think therefore I am", if parsed as "p⊃q", is not a tautology, is invalid, and need not, at least on that account, be accepted as 100% certain — Banno

Because there is an unstated premise (many depending on how deep you wanna go). Not a big deal.

Now what I have asked is for someone to present the structure of the argument. If you have indeed done so, then I've missed it. — Banno

You have:

Whatever thinks, exists.
I think.
I exist.
The first premise is an intuition, the conclusion is not, because it very clearly derives from the premises (inference). We start with a universal, then to a particular, then the exclusion of the middle term. — Lionino

I will restate this syllogism at the end of the post to reply to something else.

To doubt some statement is to take other statements as undoubted — Banno

Like the law of non-contradiction. There was no such thing as dialetheias back in Descartes' times, and many would say that there is still no such thing as dialetheias. As I said, Descartes uses hyperbolic doubt, not unbounded doubt. He makes the point here:



Descartes was interested in proving whether something exists, not proving whether LEM comes from LNC or LNC comes from LEM.

Which is valid. 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. This seems not to capture the quality of the Cogito. — Banno

Let's say pink then.
U(x)(Px ⊃ ∃(y)(x=y))
U(x)(Tx ⊃ ∃(y)(x=y))
These two arguments are identical in form but different in content, the difference in content being the statement that x instantiates the property of thinking or of being pink. 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.

P1 Everything that is pink exists.
P2 I am pink (whatever that means).
C I exist.

A1 Everything that thinks exists.
A2 I think.
B I exist.

P1 and A1 are evidently true, as you have agreed. C and B follow from their premises, however P2 may be objected, A2 may not, ever.

He could doubt physical reality, he could doubt the existence of other minds, he could doubt the existence of gods or dogs or whatever, but if he doubted thought, the wall he hits is that that doubt is a thought... — flannel jesus

:ok:

I do not think the Cogito convincing, on Tuesdays and Thursdays. Monday, and Wednesday, I'm quite convinced. Friday and Saturday, I take an agnostic position. Sundays, I rest.

Now, you think the Cogito is grounds for being 100% certain of your existence, on the basis of an intuition... is that right? — Banno

Funny how you are the one who is playing the skeptic now :snicker: the tables turn

So, do we agree that "p⊃q" is invalid? — Banno

The shape p→q is invalid under a broad definition of invalid, yes. Before you question me on what I mean by "broadly invalid", I will quote flannel quoting the SEP:

Valid: an argument is valid if and only if it is necessary that if all of the premises are true, then the conclusion is true; if all the premises are true, then the conclusion must be true; it is impossible that all the premises are true and the conclusion is false.

A notion of validity seems to imply that there are premises and a conclusion, which p→q does not have. So under a broader notion of invalid (where validity does not even apply), p→q would be invalid, yes.

If yes, then do we agree that the Cogito is "I think, therefore I am"? — Banno

The translation of cogitō ergo sum is "I think therefore I am", nothing else.

If no, then what is the Cogito? — Banno

First-person singular of the present indicative tense of the verb cogitāre.
If you are asking what Descartes' argument is, I summarised it a few posts above a few times. For the actual argument, I can only recommend the books.

1. I think ⊃ I exist. (Cogito, assumption)
2. I think. (assumption)
3. ⊢ I exist. (1.2, MPP) — Banno

Descartes did not put his argument in syllogistic form, so there are a few ways you could translate it. Still, I will concede that is not Descartes' argument.

That as such, it would be circular? — Banno

If you are using ⊃ as material implication, is this https://www.umsu.de/trees/#(p~5q),p|=q circular? The problem for me is again that the first premise is unproven, not that it is circular.

And it seems we agree that the Cogito is — Banno

Descartes' argument itself is not an intuition, it is a full-fledged argument as I have shown and as can be verified in the books. 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=5).

Then, returning to the topic, do we have some basis for thinking that this intuition counts as part of the 100% certain knowledge that the OP seeks? — Banno

If the OP does not wish to doubt our basic intuitions of reason, which would undermine reason itself, Descartes' argument would count as something certain.
But then again, now OP seems to be sure even of things that he has no way of knowing for sure, such as the day of his birth.

Well put.

So are you, in a somewhat constipated fashion, saying that the cogito is not an inference, but an intuition? — Banno

We have literally gone over that before. Fine.

"I think, therefore I am", rendered as "p⊃q", is invalid. — Banno

This is wrong. Not even wrong, it is pointless, and it could be remediated by reading Descartes¹. His "argument" is not "I think therefore I am", that is the conclusion of the whole Second Meditation. It is a very classical syllogism of the type "Socrates is mortal", and I have addressed it when talking to Beverley already.
Whatever thinks, exists.
I think.
I exist.
The first premise is an intuition, the conclusion is not, because it very clearly derives from the premises (inference). We start with a universal, then to a particular, then the exclusion of the middle term.

1 – Has anyone here?

You then say:

What you call "the complete argument" is obviously circular. Hardly convincing. — Banno

It is not circular, as I have shown clearly, otherwise "Socrates is mortal" is a circular argument even though it is the most classical Aristotelian syllogism that gives us what a deduction is.
Which I explain here https://thephilosophyforum.com/discussion/comment/890828

And by the way

You are playing on "solid" here, on the he misapprehension that we can only know stuff if we are certain of it, if our belief is indubitable. — Banno

No you. If "solid" can mean anything in the context of belief, it is a belief that can't be doubted.

The part I quoted is not even that, it is this:

Here's a seperate point, made by Corvus, Beverly and myself, and pretty much unaddressed by others: It has not been shown that the Cogito is valid.

Indeed, in propositional logic, the Cogito would be rendered
1. p ⊃ q
Which is invalid. — Banno

Which I have already addressed when you made the same claim some two pages back.

https://thephilosophyforum.com/discussion/comment/890383
https://thephilosophyforum.com/discussion/comment/890542
https://thephilosophyforum.com/discussion/comment/890828

Here's a seperate point, made by Corvus, Beverly and myself, and pretty much unaddressed by others: It has not been shown that the Cogito is valid.

Indeed, in propositional logic, the Cogito would be rendered
1. p ⊃ q
Which is invalid. — Banno

It feels as if we are going back in time when such fallacy had not been addressed already.

Sadly, all the explanation you put forward has been given by either me or flannel before, to no avail. I ask that you spare your sanity.

You assume your conclusion in the first line of your argument. — Banno

I don't assume my conclusion in the first line because their contents are different. I am quite sure that what you are trying to say instead is that the argument has an unproven premise.

If you wanna know, Descartes talks exactly about this in his Objections and the Principles:

Screenshot is from "The Anatomy of the Soul".

It's not a proper syllogism, yet you present it in syllogistic form? Make up your mind: is it an inference, or not? — Banno

The catchphrase is not a syllogism, the complete argument is.

Is it a valid inference, on which we must all agree, or is it an intuition, a mere hunch or impression? — Banno

It is a valid inference as I have shown. As to the others, I am not sure what you mean by them, and my brain is too fried today to try to reply.

This error leads folk to conclude either that we must build our knowledge from solid foundations — Banno

You yourself said earlier "you must start somewhere". A start is a foundation, if you agree that we need a solid one, you side with Descartes, if you are of the side that we don't need a solid one, you are a skeptic and a pragmatist. Pick your poison.

Let them show us how. — Banno

But Corvus is correct that the Cogito is not valid, at least in its usual form. "I think, therefore I am", rendered as "p⊃q", is invalid. — Banno

The catchphrase "I think therefore I am" of course is not a proper syllogism, and it doesn't have to be, the complete argument is:
Thinking → existing
I think
Therefore I exist

That every single philosophical argument needs to be put in syllogistic shape is a fantasy. It is more than impressive that cogitō ergo sum, the crowning achievement of the father of modern philosophy, needs to be defended against so many bad arguments in a philosophy forum.

Your formula seems incorrect. This is the correct one. — Corvus

That means nothing in this context. You can change it to https://www.umsu.de/trees/#(p~5q)~2(p~5~3q) or https://www.umsu.de/trees/#(p~5q)~2(~3p~5q) and it remains valid.

I agree cogito is not a logical statement, and it looks doubtful if it is even an inference. — Corvus

That was never your argument.

(P -> Q) = -P or Q (P. Bogart) — Corvus

Curious, you were just saying how Bogart is not god. In any case, I already proved how this is in full agreement with Descartes:

I think → I am. P is "I think" and Q is "I am".
P – Q – ¬P∨Q (aka P→Q)
0 – 0 – 1 "I don't think and I am not" holds P → Q
1 – 0 – 0 "I think and I am not" does not hold P → Q
0 – 1 – 1 "I don't think and I am" holds P → Q
1 – 1 – 1 "I think and I am" holds P→Q — Lionino

It seems that compared to the OP, he is malfunctioning, as then he clearly understood the problem of skepticism, but now he seems to think that it is a complete logical impossibility that he is adopted or that he got switched up in the hospital.

You, the existing one (as premise), thinking or saying or being, to conclude “I am” - it’s not bad logic, it just just a tautology that doesn’t tell you anything you didn’t already know. — Fire Ologist

It seems tautological because it is so obvious, and it is obvious to us now because he pointed out, but he did have to point it out.

I'm not at all sure we are disagreeing here. — Banno

I'd refer you to yourself:

This is said without irony? — Banno

In Chess, it is true that the bishop stays on it's own colour. — Banno

Without the bishop staying in one colour, it wouldn't be chess. Because of that, the above is simply an analytic statement of "If the bishop stays on its own colour, it is true that the bishop stays on its own colour", which is non-informative. I could raise an issue about analytic statements, but when I say nothing is set in stone I am referring mostly to a posteriori judgements. Every "it is true that..." has implicit "ifs", each "if" is a drop of uncertainty. Skepticism is a problem, a problem must be recognised before it is overcome.

Stressing about Skepticism is futile, agreed. If Hume cannot overcome it and Kant cannot defeat it, what hope do mere mortals have?

Still, it's worth keeping it in mind as a problem. For ignoring it completely defeats the point of what is right about it, that we cannot attain certainty - in this world at least. — Manuel

Well put and case in point.

Physically no, but metaphysically and logically? May be or why not? — Corvus

Because... it is not logically necessary that there is life in Mars, and we know there is none there.

Cogito to "I exist" is a deductive leap, tautology or just monologue. Problem with Cartesian cogito is, it lacks the content. Lack of content in cogito allows even denial of Ergo sum. What if, the content of cogito was "I doubt" or "I deny"? Does "Ergo sum" still stand? — Corvus

You say the cogito lacks content, which doesn't make sense, then you say "what if the content was...", implying it has a content different from what you were about to say, meaning it has content.

Are you serious my guy? — AmadeusD

No one making Deepak Chopra-like claims is serious.

That's much better than the incoherent claim that we know nothing, or its inane sibling, that there are no true statements. — Banno

When someone says they "know" something, 'know' is a word with composite meaning, indicating at least an attitude (belief) and a state of affairs (being true). To say you know something implies a commitment to something being true, and for me that implies certainty, which is why I think it is faulty when people say they "know the sky is blue" like they "know" they "can trust their eyes", as one is reliant on the other.
But if you want to say that knowing is not the commitment that something is true but that it is much more likely than its opposite (not-X), I am happy to say we know many many things.

One can't play chess without the certainty that one's opponent will keep their bishop on the same colour. — Banno

One can hardly discern whether there is something "true" about the game they just made up to communicate or whether it is a useful fiction.


Are you trying to apply mathematical operations to English? Because
* "It is set in stone that there is nothing set in stone" and
* "It is not set in stone that there is something set in stone"
can mean completely different things, even though both are made of a negative with a positive.

Or we can accept skepticism and carry on from there without stressing about certainty, knowing that we will die is as likely or less than that we were born.

Lakatos? — Banno

From the quotes thread.

Is it set in stone that nothing is set in stone? — Banno

Yes. Therefore something is set in stone. Therefore it is not set in stone that nothing is set in stone. Therefore nothing is set in stone. This is a paradox! Exactly. Further showing how nothing is set in stone.
No. Therefore that is not set in stone. So what is it that is set in stone? It seems no one has clarified it yet. Some might say it is the law of identity, but that one is shrouded in mystery.

You are clever enough to understand that we must start somewhere... — Banno

We can start from wherever we want. Knowledge can be like mathematics or logic where we can choose the axioms we want. But it is only certain axioms that give us good theorems. Some people start with the Christian God, others with PNC (but is it more fundamental than the PEM?), most people with a collection of brute facts ("I just know that gravity is 9.81m/s²!"). If we start with the negative that we don't know, we might stop worrying about being certain about things (as if certainty even exists) and start worrying about being less uncertain in general.

This is said without irony? — Banno

taking a dim view of what he described as the Wittgensteinian “thought police” (owing to the Orwellian tendency on the part of some Wittgensteinians to suppress dissent by constricting the language, dismissing the stuff that they did not like understand as inherently meaningless)