His view of the condition of truth being found outside of what 'belonged' to oneself was brought together with needing to make decisions that shaped what life will be. Our ability is directly involved with those choices. — Paine

He considered as absurd the philosophical and theological attempts to prove/disprove the existence/nonexistence of God. Instead, the commitment to live an authentic Christian life must be rooted in a "leap of faith." And so one who lives an authentic Christian life is the Knight of Faith. — Arne

Great points. Thanks for your replies. :cool: :up:

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. — Banno

Sure, good point.  They disputed that Not P -> Not Q doesn't make sense. But the logic checker says it is valid.

(p→q)∨(¬p→¬q)
(P -> Q) = -P or Q (P. Bogart)

We know and they even admit that Not Q = False
So it must be P -> Q = Not P or Not Q
P-> Q = False (proves I think therefore I am, is false).

Because Cogito is a psychological statement or intuition, it is very awkward to prove its validity using first order logic.

It is like a psychological statement, I feel happy, therefore I dance.
The statement is an obscurity itself.  Who is "I"? And what does "I" feel happy about? We don't know.

The same goes with Cogito ergo sum. I think therefore I am. Who is the "I"? and What is the content and object of "think" in there. It is unclear. The only "I" know, is my "I", but I think I am doesn't warrant I am. Rather, what I see, feel, sense, remember and reason is a warrant for my existence. And it is absolute a private state of mentality.

We would never know anything about the state or nature of Cogito, who it belongs to or what the Cogito was about.

Perhaps for this type of purely psychological statement logical analysis, it would be better to use Kripke frame,  Epistemic or Intentional Logic, and check for its validity.  It would turn out to be invalid for sure.

Just was suggesting a would-be better formula. Not biting your hands at all.
My point was the content of Not Q was FALSE, therefore the original assumption P -> Q is False.
The 3 dualists have been havering with their muddled examples which didn't make any sense at all.
I agree cogito is not a logical statement, and it looks doubtful if it is even an inference.

He's been called the Grandfather of existentialism. He drew attention away from grand project building (like Hegel) to the experience of being alive: to that 'quality of being that comes to rest in the sanctuary of the form.' — frank

He had all the symptoms. His primary concern was on the existence of the individual. Anxiety, dread, authenticity. . . . He was a significant influence on Heidegger. — Arne

K. seem to have had close connection to Christianity and God in many of his writings. How does his concept of God fit into existentialism?

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

Your formula seems incorrect. This is the correct one.

Cool, this exactly Descartes' argument, but put more poorly. — Lionino

Descartes said "He thinks, therefore he is." What are you talking about?
Thinking is not totality of mind. Thinking also has objects and contents. Descartes didn't even specify what they were. Hence it wasn't even a logical statement. As you admitted before, it was an inference.

Thanks for wasting everybody's time. — Lionino

I have been only trying to reply to your questions and posts.
Everything you say seems not reflecting the reality or facts.

So why did you even quote him? — Lionino

To get some ideas. Did you think I quoted him because he was a god? blimey :roll:

This makes no sense. It is not a coherent thought. — Lionino

Could it be a psychological block somewhere in the thought?

IOW if I look at many of your posts it seems like you are saying the rule shows that it's false. But the moment you indicate that it works 'in this case' (but not in others), it seems to me, this is directly acknowledgement that it's not the rule. It's a specific situation or a specific condition, for example the 'if and only if case' special condition. — Bylaw

But rules are for us to apply them into the individual cases. Rules don't exist just for rules themselves, or for its own sake of just existing as rules. When you are going through the rules inspecting the corresponding real life cases, you can see the truth or false values by comparing them with the reality in the world, or the state of objects or situations.

Having said that, I agree with your point, that this particular case would have done with more stringent conditionals on the premise and also the assumptions.

The bottom line is that, Logic is not the core problem here. Logic was introduced to help clarifying the main point Cogito. Unfortunately it didn't seem to help much in doing so. As I said in the other thread, sometimes psychological bias seem to override logical arguments.

Cogito could have been not a statement that can be proved logically first place. Because it was never a logical statement. So, if we agree that Cogito is an epistemological issue, then it still is absurd to say Cogito necessitates existence. It would be rather perception, memories, imagination and sensations as well as reasoning and all the rest of the total mentality which grant one's own existence, I believe.

:rofl: :rofl: :rofl: So you are disagreeing with P Bogart, who you yourself quoted. That's crazy. — Lionino

This is exactly the point I was making with misuse of Logic. P Bogart is not a math god. He is just a math teacher.

At Not P --> Not Q, if you were sensible, you would have inspected the content, which was FALSE.
Because it is FALSE the assumption, P->Q must be FALSE. You are guilty of the misuse of Logic.

You seem to be naively following the symbols as if they were some message from God.
You must inspect the contents of the symbols to decide for truth values as you keep progressing your reasoning and inferencing mate.

0 – 0 – 1 "I don't think and I am not" holds P → Q — Lionino

I don't think and I am not is FALSE.
so P -> Q is false at that point.

The evidence that you are psychologically biased is based on the fact that, you don't even accept my proposition that we can agree to disagree, and end the discussion. Because obviously no matter what logic and explanations were offered to you, you cannot see it, or accept it. The only way for the closure would be we agree to disagree. That is a fair solution. But you refuse to accept it.

OK, I was under the impression you were arguing with only the general rule. IOW positing a general rule that generally is considered false and the examples I and others have given, I think show it's not a good rule. — Bylaw

Yes, but your example and the other's examples are the case of categorical mistake. This is the problem with the symbolic classical logic. Because it uses variables instead of the real objects and cases in the world, they think they can use any irrelevant items and cases into the variables, which looks like the general rules doesn't make sense. That is why sometimes you must investigate the content in the propositions to see if they make sense.

But your point is good in that it reveals the problems with the misuse of the logic.

Your example, bank robbery has nothing to do with rape the criminal committed. They are totally separate matter. And yet, the criminal was trying to distort the truth as if they were the same category of crimes. They are different category of crimes. It is like saying

Socrates is a man, therefore he is mortal.
A dog is not a man, therefore he is immortal.

You swapped over Socrates with a dog. That is illegal in logical arguments.

And, hey, post a picture of the textbooks. If it's there, that will surprise people and might move things forward. — Bylaw

I am no longer communicating with the folks who appear to be psychologically biased on this topic.

Oh, and this isn't because I buy or like the cogito. I actually don't. — Bylaw

That's cool. :up:

Fully agreed — flannel jesus

Good :nerd:

I agree with your idea that language is a tool to communicate, and it can be unclear at times for philosophical discussions.  But we also have  Formal Logic which can aid in clarifying the obscure ideas, statements or propositions.

But at times, Formal Logic can also present ambiguous conclusions due to its limitations. Hence it is good to have both tools, and use them together when one is lacking in the clarification process.
This is especially the case with the classic symbolic logic.  It can sometimes mislead the folks or be abused for presenting illogical sophistry as truth.  That is the reason why there are so many different types of Logics available for us to use e.g. Modal Logic, Fuzzy Logic, Epistemic, Dynamic, Intentional, Institutional, Description Logic .... etc.

Another point that you must note is that, Logic is not an effective tool for those folks who are psychologically motivated to push their own ideas to other folks.  For them logical arguments and proofs would mean nothing for changing their biased views on certain ideas they wanted to push to other folks.  They won't accept logical truths as truths.  They will keep denying verified and proved truths as fallacies.

Reasonings and Logical proofs are only effective for those folks who are authentic and willing to accept truths as truths.

For your question do we need a unified language in Philosophy? I would say No. It won't make difference what language or formal logic you use. If some folks are psychologically biased on something or some ideas, then no logic, no reasoning and explanation can change his views or enable them the point. IE psychology overrides reasoning in philosophy in some cases.

I agree. For Sartre, individual existence is freedom. For Heidegger, individual existence is being-in-the-world. For Nietzsche, individual existence is will to power. — Arne

Was Kierkegaard an existentialist? In what sense yes or no?

Destruction is purely physical, whereas violence is physical plus psychological.
Therefore attributing violence to the natural disasters sounds absurd.
Violence can only be attributed to the agents with psychological motives and sufferings.
Violence can happen without physical destruction e.g. in mental level.

I don't see any possible relevance or link between art and violence.
Likewise, I can't see any link between art and destruction. They are not relevant in any shape of forms.

Of course, there can be situations where denying the antecedent can also be true. But if it is presented as a logical necessity, it doesn't hold. It's not enough. Throw in an if and only if, and it can work, but that's a different condition. — Bylaw

Good point. I am not going to deny your point straight away. I wouldn't be that rude.
But it seems that you talking about again totally different case in your example. Why it is irrelevant, if you want know, then let me know.

I looked at one of my old textbook called "Discrete Mathematics" by P Bogart.
It says, P --> Q is equal to ¬P V Q.
This makes sense, and seems to prove my logic was correct.
I think therefore I am is unsound.

I thought our discussion had been over about 10 pages ago. You kept on hounding me with the same daft questions and irrelevant comments for some reason. It just seems to me some obsessive troll you are after. Nothing more to add, and nothing more to discuss with you for this particular topic, afraid. Bye.

Obviously your syntactic confusion has been adding to the whole mix up. Good night.

what in the world are you talking about? — flannel jesus

You are totally ignoring the plant you were talking about in the proposition, and suddenly starting to making random inference of holding some other plant. Do you not even know what you were talking about?

But you are not holding the plant. You could be holding a plant.
You are not even able to difference between "a" and "the".

I haven't failed to find the book. I didn't even try to look at any book.

P->Q then
Not P -> Not Q

Why is this fallacy?

As I made clear already I am not going to flick through a Logic book to whatever ... no. There are more important thing to do in life.

If you cannot see my point in the written expressions, then there is no point I am afraid.

P: I think therefore I am. (This is the one you want to prove correct or not).
Q: I don't think therefore I am not. (This is implied from P logically oK???)
So, P ---> Q

But you know Not Q
Therefore Not P

It is so clear, what is it that you can't see ?

It is not MP or MT which is important here. They are just tools.
You seem to making out as if MP MT are some end point human race must achieve.

The core problem is to prove or disprove "Cogito Ergo Sum." is logically sound.
For that, normally folks wouldn't even need any Logic.

I only introduced the simplest Logic because you seem to be having difficulty in understanding anything on proving. But for some reason, you seem to be excited and obsessed with the definition of MP.

Well, if you cannot even understand what the core problem is about, what is the point of you learning about MP or MT or the rest of Logic? Please tell me what is the point you don't see in my post above, and I will try to explain it to you again if it looks any worthwhile.

Nope. You are wrong in your unfounded presumption again. I am not going to take out my logic books on my relaxing weekend time, just to prove what is self evidently true.

The explanation above in my post above is clear enough for this simple point for anyone to understand what it means. I hinted you to read some proper textbooks instead of keep getting confused based on ChatGPT's nonsensical info.

The core problem we were trying to prove is so simple and clear. Why do you try to make it complicated introducing the irrelevant points into it?

Post the pictures — Lionino

I cannot find the page relevant to this point in my logic books. I came home, sat down at the desk, and reviewed the whole point again. I still feel that Cogito Ergo Sum seems logically not sound.

P = I think, therefore I exist.
Q = I don't think, therefore I don't exist.

P - > Q
Not Q (Q is FALSE)
therefore Not P (P is FALSE)

One's own existence is known by perception and sensation rather than just thought, no? Surely you must keep existing even when not thinking. Is this is the case, then I think therefore I am is not logically sound.

Holy shit. Obviously nobody said that. That doesn't even make sense. "I think therefore I am" is an inference. How can an inference be the only way for something to exist? — Lionino

Exactly :nerd: No wonder it didn't sound tightly logical necessity.

Is this you confirming that you won't post the pictures if they don't confirm your beliefs? I truly hope that you can be better than that — flannel jesus

I am trying to focus on the discussion with without getting interrupted by the unusual requests and irrelevant posts.

Please save this argument for after you post the pictures from your textbook. Your argument will hold more weight then - or it will disintegrate, depending on what's in the book. — flannel jesus

Sorry but I am discussing this point with . Will get back to you after our discussion, if there is any more point for us to discuss on this particular point. If I don't, then you know the answer.

No it doesn't prove that. Your next move is to say "Why not". Because burden of proof is not on me. — Lionino

I don't think you showed any arguments for it doesn't prove that, did you?

Obviously, because you can't recall what you said 1 page ago, you will say those two are different. But: — Lionino

Classic symbolic logic works by showing how the arguments transit from one to the other mainly using the variables. Sometimes you would introduce negations, AND, OR connectives in the process of proving. But in the process, if you noticed the critical point where it disproves the core points, then it will deduce the conclusion from the statement which is obviously true or false. This is the way the logical proving works. You seem to be totally ignorant of how the proving procedure works. It is like those folks who are into the habitual copying and pasting truth tables and some symbols in the internet, and insist that is the only way MP works what have you.

If you say, you think therefore you are, is the only way for you exist, then when you are not thinking, you stop existing. That is what you mean logically. Don't you find that absurd?
Do you stop existing, when you are asleep, or watching movies or listening to the music with no thoughts?

How about the walls in your room. The wall don't think. Does it mean they don't exist?

Please also understand the core problem here was proving whether "I think therefore I am." is logically correct. All the rest was just introduced as a process for the proof.
Your insisting on requesting photographic evidence of the textbook ... etc, sounds very bizarre to me.

If you can't see the simplest logical proof shown to you with the explanation for the point, then that is fair enough. There is really nothing anyone can do about that to change your belief.

No, it is nothing to be sad about. People disagree in the real world, and you must learn to accept it.

We agree to disagree on the point, and that is fine by me. I really do hope to see you understanding the points though. But if not, so be it.

I have given you the full proof using both symbolic logic and ordinary language. If you can't see it, then that is fine. I don't feel there is a point for any more discussion here on this particular point.

I don't think it needs any more time wasting mate.

You have admitted that When you don't think, you don't exist is incorrect.
That proves, When you think, you exist is also logically incorrect.
We didn't even have to go into the symbolic logic.
Why is it so hard to see it?

All I can say is, if you are that bothered with something, please read my post again for proving why "Cogito ergo sum" is logically incorrect.

You obviously don't even understand what the core problem is. The core problem is proving "Cogito ergo sum" is correct or incorrect.

It shows you are also one of the copy-paste internet info brigade without even knowing what it is, but not even knowing what we are trying to prove here.

Except for Stanford University and Oxford University, for starters. — flannel jesus

Now it gives me an impression FJ is a robot machine set up for keep replying automatically without even knowing what it is talking about. :roll: :chin:

You think therefore you exist? -> T (Assumption)
P -> Q = T (assumption)

When you stopped thinking, you don't exist? (jesus has admitted it is incorrect) -> F
Not P > Not Q  => F
T F -> F
P -> Q = F
Therefore you think therefore you exist is FALSE.

Please note T F are truth values of the propositions.They are not  propositions themselves.
Well, this is the last time I am trying to make you understand.  If you still can't, then I don't think there is hope.   It is shocking that 3 of yous are all in the same cave of confusion.  No one seems to be able to dig yous out the cave.

I shall give a try as per time permits.