Banno

Good. So you agree that, since for you it is not an argument, then it is not a valid argument. Now, if it is not a valid argument, then it cannot be a...

Here's the point: "I think, therefore I am" is not a valid argument if it is understood as p?q. Even you must see that.

No. That is not what I said.

Oh, Flannel. https://www.umsu.de/trees/#p~5q I'll leave you to it.

Think about truth tables. A tautology will be true, regardless of the values assigned to the propositional variables. That is, tautologies are valid; ...

If you won't accept such basic stuff, there's not a lot of point in discussing logic with you.

Validity is more formerly defined together with satisfaction and contradiction. An expression is satisfiable if at least one interpretation makes the ...

, continuing... If we agree that the argument quoted is not the Cogito, then do we agree that it is also not a proof of the Cogito? That as such, it w...

Well, yes, you are repeating yourself. But if you think that "p?q" is not invalid, then let that be an end to the discussion. So, do we agree that "p?...

Any time now, one of you can mention that Descartes held that issues clearly and distinctly perceived are indubitable. That'd at least move the topic ...

So are you, in a somewhat constipated fashion, saying that the cogito is not an inference, but an intuition? Fine. But it is not clear why an intuitio...

Just to be sure, this: ...is not a proof of the Cogito. As has been pointed out, it can't be, because it assumes the Cogito on line one. Nor is it the...

And still you kick. Even I give up after a page or two.

:roll: What fallacy did you mean?

Oh, I see - you just wanted to join in the kick fest. What fallacy?

Here's the Cogito: Cogito: I think ? I exist Here is a mooted proof that I exist, from various corespondents... 1. I think ? I exist. (Cogito, assumpt...

Yep. True, but invalid.

Are there assignments of true and false for which it is false? Yes. Hence it is invalid.

https://www.umsu.de/trees/#p

I now sincerely regret having become involved in this discussion.

A formula is valid only if it is true for all assignments to its terms. Here's the truth table for implication: https://i.stack.imgur.com/KiJ8A.png p?...

But p?q is invalid. From p it does not follow that q. Are you sure you understand validity?

So... (((p?q) ? (~p?~q))?q)?~(p?q) or (((p?q)?(¬p?¬q))?q)?¬(p?q) Still invalid.

The inference is invalid. logic does not show that if 'I think therefore I am' is true, then 'I do not think, therefore I do not exist' must also be t...

((p?q)&p)?q is valid, and on one line. But if one denies p, then the argument does not bind one to q. And I ought correct myself, or at least finesse ...

Go on, set out your reductio. Line 1 is invalid (edit: it is valid in S5). Again, you presume your conclusion.

Is that what you wanted to show? That's not the cogito.

It means "get on with it".

:roll: It is valid.

Mind your p's and q's. What are they?

Well, it seems from the length of this thread, that one can doubt that, too.

Consider this: we know things despite not being "100% certain".

Ok, so from what is it to be inferred? And if the answer is "I think", then how is the inference valid?

I've set out my view. The project here, to find something indubitable, is the source of the problem. Just as we can require reasons to believe, we can...

A better account than others have provided. Can you doubt that you are now reading my reply? Point being, at the level you want to work, there are qui...

All, can you see that the Cogito does not provide the certainty you crave?

Notice the presumption in that? Consider again Russell's objection - There is thinking occurring, but what is the "I"? The other reading, which you mi...

Why? p?q is not a valid argument. Move past attacking Corvus ad nauseam, we agree that he does not show the Cogito to be invalid. But can you show it ...

Can you show that the Cogito is a valid inference? Can you set out it's logical structure, so that we can see why we ought accept it's conclusion, if ...

What you call "the complete argument" is obviously circular. Hardly convincing. You assume your conclusion in the first line of your argument. You are...

So it's an intuition. Is that sufficient for the foundation of knowledge? No. If someone has an intuition that folk born under Pisces are natural lead...

(p?q)?(¬p?¬q) is invalid. No, it's invalid. It can still be true under some interpretation. It can also be false under some other interpretation. But ...

:chin: p?q, q?t ? p?t. is the Hypothetical Syllogism.

You wrote 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 wi...

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 ...

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 2.0...

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. Thi...

Yep, truth keeps getting in the way.

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