So it must be P -> Q = Not P or Not Q — Corvus

(p→q)↔(¬p∨¬q) is invalid.

P -> Q is FALSE. — Corvus

No, it's invalid. It can still be true under some interpretation. It can also be false under some other interpretation.

But of course, that you have not shown the cogito to be invalid does not imply that it is valid. @flannel jesus has not shown that the cogito is valid - if indeed that is their supposition.

_______

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 — Lionino

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

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. — Lionino

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

_______
Underpinning the whole of this thread is the misapprehension that we can only know stuff if we are certain of it, if our belief is indubitable.

This error leads folk to conclude either that we must build our knowledge from solid foundations, such as the Cogito, or else that we do not "truly" know anything. Both views are muddled.

Obviously not sound. — Metaphyzik

:chin:

p⊃q, q⊃t ⊢ p⊃t. is the Hypothetical Syllogism.

You wrote

(I think, therefore I exist) or (I don't think, therefore I don't exist)

All your friends need do is deny the right of the disjunct - which they have done.

I simply fed what you said in the quote above into the tree proof generator, verbatim.

But go ahead and bite the hand that feeds you. I am agreeing with your more general point that the validity of the cogito is questionable - indeed, it is questionable if the cogito is an inference. Your interlocutors seem to think that it is logically undeniable. Let them show us how.

In symbolic classic logic, the contents don't matter. It works purely on the format.
So if you say,
P-> Q
Not P
Then it must be Not Q

There is no way Not P, and it is still Q. — Corvus

Corvus' argument here is of course invalid - tragic that this should need saying.

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.

One needs to get inside the existential quantification if one is going to show validity. That is not an easy task.

Try it for yourself, see if you can avoid circularity.

Hence the common reading of the Cogito as an intuition rather than as an inference.

I don't think there is much point in taking up the discussion. It's too far gone.

But I insist on giving more weight to 1.1 over the first half of 2.021, misconstrued.

Consider also

2.0231 The substance of the world can only determine a form, and not any material properties. For it is only by means of propositions that material properties are represented—only by the configuration of objects that they are produced.

Facts set out the configuration of objects. Nothing can be said about objects apart from how they are configured - the facts; Attempting to say something about objects apart from their configuration is attempting to say what instead must be shown. There is nothing much that can be said about objects per se; they are instead shown in their configuration and presumed by the facts.

It has also to be understood that the Argument for Substance is rejected in PI. See especially §60-64.

In the place of some ultimate analysis of substance, or of logical atoms, or of ultimate simples, is left the various games we might play, and what we are doing in each case. What is foundational depends on the task at hand - forget about meaning, and look to use.

To understand Wittgenstein with any depth one must read the Tractatus and the PI side by side.

I'll leave you to it. But the answer to the OP is that from the perspective of the Tractatus, nothing can be said about substance or atomic objects; one can speak only of their configuration. And yes, this doesn't work, hence the Investigations.

...all muddle... — schopenhauer1

Yep. Folk hereabouts have missed Tractatus 1.1. They are trying to understand of the Tractatus as founded on objects, when it is founded on facts.

This is the worst thread so far on Wittgenstein. Quite an accomplishment.

The power of the factual is immense and prevents us from taking on other perspectives. — Wolfgang

Yep, truth keeps getting in the way.

Probability, not Certainty — Gnomon

So you are now saying Bayesian inference is only probably correct...?

To say you know something implies a commitment to something being true, and for me that implies certainty — Lionino

Good for you. If something is known, then one can conclude that it is true.

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. — Lionino

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

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

That is to say, it would be a matter of empirical investigation to find out, both what the constituents of a thought are and how they are related to the ‘objects’ occurring in facts, that is to say, to the objects designated by the ‘names’ in language. — Summary, p. 28

What the objects are is "a matter of empirical investigation to find out", not an issue to be addressed in The Tractatus. It is irrelevant to the work at hand. As I said, what an atomic object is, as Anscombe argues, unimportant to the argument in the Tractatus as presented.

Immediately, Anscombe adds:

That this is fantastically untrue is shewn by any serious investigation into epistemology, such as Wittgenstein made in Philosophical Investigations. But it is fair to say that at the time when he wrote the Tractatus, Wittgenstein pretended that epistemology had nothing to do with the foundations of logic and the theory of meaning, with which he was concerned. The passage about the ‘elucidation’ of names, where he says that one must be ‘acquainted’ with their objects, gives him the lie. — op cit.

Now it remains unclear to me what you are claiming, but I don't much care.

If you or suppose Wittgenstein to be arguing that the world is made of objects, that objects are the fundamental building blocks in the Tractatus, you have badly misunderstood what is being argued.

That's a nice little cage you have built for yourself.

Maybe see https://thephilosophyforum.com/discussion/comment/826747

So the dog knows that it is raining, even though the dog cannot say that it is raining. The content of the dog's knowledge is given by "it is raining", even though the object of it's knowledge is not the proposition that it is raining, but the rain.

Subtle, easily misconstrued, but important.

Yep. That was my point ). What animals know can be put into a proposition. The content of an item of knowledge can always be put into a proposition.


Knowledge is propositional.

First off, what you referred to was not about simple objects: — Fooloso4

That was what I was talking about.

I've no clear idea of what you are talking about, if not objects. Here is where you joined my part of the conversation:

Does Anscombe mention a single simple object? The claim that language demands it is not the same as actually identifying either a simple object or a simple name. — Fooloso4

That sentence appears to me to be about objects.

You are all over the place.

What an atomic object is, as Anscombe argues, is unimportant to the argument in the Tractatus as presented. I'm arguing along with Copi and Anscombe that names refer to particulars, along the lines of individual variables in modern logic. Further I think that the way in which simples are viewed is one of the main changes between the Tractatus and the PI.

But the vital thing here, which permeates all of Wittgenstein's work, is that the world is not made of objects but of facts.

That's the view that I, and I think @Sam26, are setting out. And again, while your tone suggests that you adamantly disagree with me, I really do not know what it is you are suggesting, and hence how you agree or disagree with what I have said.

So unless you are able to explain what it is you are saying in a way that is comprehensible, I do not see how this conversation might proceed.

Hu?

Nuh, best leave it.

Animals know things, but what kinds of beliefs do they have? Certainly not propositional. — RogueAI

So can you tell us, without putting it in a proposition, something some animal knows?

You are only as certain as how much you can convince yourself of certainty. — Beverley

Yep, certainty is a form of belief, not of truth. One can be certain of whatever one choses. Or doubt whatever they like.

What I am pointing to is simply the performative contradiction in folk expressing such certainty in their doubt.

twisting language — Beverley

You mean using logic?

I was more a Samuel Becket sort.

We can start from wherever we want. — Lionino

Yep.

That's much better than the incoherent claim that we know nothing, or its inane sibling, that there are no true statements. It has a huge pop status, a mark of rebellion, sticking it to the man, talking truth to power, and so on.

But it undermines itself.

Doubt and certainty are twins, you don't get one without the other.

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

Certainty is absurd! — Chet Hawkins

Again, why are you so adamant about this?

Lakatos?

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

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

In the post above, ( ) where you quote my comment about simple objects and then go on to reply to it as if it were about elementary propositions.

...copies of Being and Nothingness and Camus' The Outsider... — Tom Storm

Candyland sums up their relation... Camus was not an existentialist.

Just edited my previous post, as is my want.

I remember the crowds lining the street when Sartre died.

Were they being ironic?

Existentialism only works until you take it seriously.

Your bad faith is showing...


You have to decide for yourself, not just give me the nod... :wink:

Did I say or imply otherwise? Why bring this up? — Fooloso4

Because you seemed to me not to be differentiating between atomic objects and elementary propositions.

So you are certain of that formula?

Knowledge is delusional because it implies knowing which is impossible. — Chet Hawkins

And you know this to be so?

Exactly. Further showing how nothing is set in stone. — Lionino

This is said without irony?

:lol:

Can one call oneself an existentialist without irony? — Tom Storm

Well, what do you think? :wink:

You get to decide.

You have to explain what exactly you meant by know to have a good definition. — Abhiram

Justified true belief?

Subjective experience is there we know it. — Abhiram

Whatever "it" is. Our knowledge is not limited to subjective experience. For example, that you answered my post demonstrates that you know you are a participant in a social organisation that spans the globe...

The mooted hegemony of subjective experience is a philosophical conceit, nothing more.

To be blunt - my specialist area - those who have answered "yes" to the question in the OP have thereby shown that they have not understood existentialism.

Ok, but elementary propositions are not atomic objects.

See also the last whole paragraph on p.27. "The theory of knowledge is the philosophy of psychology.

I'll leave you to your musings.

Can you prove there can’t be a perfect definition of existentialism? — Rob J Kennedy

The essence of existentialism...?

Something's amiss here.

We cannot know about anything for sure. Definitely not 100%. Only thing we can be sure of is the subjective experience we have. — Abhiram

...so we know our subjective experiences for sure, and hence there is something that we know for sure, and so it is not true that we cannot know about anything for sure.

you have to at least conceptually recognize both phenomenal awareness and object awareness. — hypericin

Coming back in after not reading the diatribe since my last, we do indeed recognise the difference between dreaming of eating a steak and eating a steak. that's why we have words like "dream", "hallucination", "illusion".

It follows that we can tell when we are seeing things and when we are not.

And hence, that we on occasion see things.

You seem to be arguing the realist case.

Perhaps this is how one should think about these objects. The analysis of language demands that there are elementary propositions. These elementary propositions are about possible atomic facts, consisting in combinations of names. These names name elementary objects

Of course this is muddled, hence the PI.

Does Anscombe mention a single simple object? — Fooloso4

I doubt it. Look for yourself. That there are such things is implied by the structure of language Wittgenstein develops. What they are is irrelevant. See p. 28 op.cit - I can't easily quote from it here. What they are is an issue for psychology.

And this is what was later rejected in the PI. Anscombe does not mince words and is not protective of the Wittgenstein of the Tractatus.

But what elementary propositions are not, is simple observation statements.

Sorry - elementary propositions - Popper used "atomic propositions" and I was reading his account in Anscombe.

This is too fast for sufficient care.

(I had written that before your last post... yes, I'm going for a walk.)

1. Fact can either be the case or not be the case. — 013zen

No. If you had said "possible facts can either be the case or not be the case", I would agree. All facts are the case.

Then followed with

In the event that it is the case, a certain set of atomic facts obtain. In the event of a possible fact not being the case, a certain set of atomic facts do not obtain.

Not at all.

I haven't read the replies here in detail, focusing on your posts instead. My interest is in the change between Tract and PI. In Tract, objects and atomic propositions are taken as essential, I suspect as the result of a transcendental argument: without these, language could not work; language works; therefore there must be objects and atomic propositions.

But this is rejected in PI, replaced by meaning as use, and simples as whatever is needed for the language game.

:smile:

We are writing over each other.

An excellent few pages. Well done. Still think you should put it into WIki...