Despite appearances, I don't think Beverley and corvus reasoning is remotely similar to each other.

For one thing, Beverley rejects denying the Antecedent as a valid logical step, while corvus calls it "basic logic".

And another is, I'm not sure Beverley is aware that Corvus believes existence is required for thought.

really interesting

oddly, though, the result only holds for people who are born blind, and not who go blind as adolescents or adults.

I guess results matter to me. If you have all sorts of abstract reasons why purely voluntary education is "good", but we have all these tangible reasons why involuntary education actually lowers crime rates, increases general happiness and life achievements etc, then I will choose the latter.

I would fear that completely voluntary education would have a lot of negative consequences. A lot of people in environments with gangs would drop out even sooner than the do now to join gangs, that kind of thing. Seems like a dangerous game to me.

So imagine tomorrow you are given the reins to education. You're not allowed to abolish government, or make any changes to any governmental system whatsoever, except for changes to education. What changes do you make that are an improvement over what we have?

One would think! Unless the parents were secret CIA operatives trying to hide the existence of the last remaining challenge to the power of the KGB in russia. You have an inheretence that Putin can't find out about, or he'll snuff out your life.

I'm *almost* certain that what's on your birth certificate is correct - I don't have any good reason to doubt it - but I'm also *almost* certain there are people in this world who are equally as sure as you are, and equally as justified, about what day they were born and, and who are *incorrect*. You probably aren't one of those people, but you could be!

I'm not suggesting you should behave as if you're not certain, of course. Don't go scream at your mom to tell you the truth of your Russian inheretence please.

Hold on, I should have added, IF you are playing by the rules of logic, and the original premise was valid and logical, then, if what I have read is correct, the 'not P, not Q' reasoning would not hold. — Beverley

I missed this the first time around. I apologize. I applaud you for reading the material on symbolic logic, even though you were unfamiliar with it, and coming to understand some operations of basic logic.

You are correct, if we are playing by the rules of logic, the 'not P, not Q' reasoning does not hold. And we ARE playinig by the rules of logic - if someone could use the rules of logic to prove the cogito entirely incorrect, then I personally would abandon it. Corvus tried to do so, but a step in his reasoning was going from 'if p then q' to 'if not p, then not q', which means that his particular line of reasoning was not the line of reasoning that would convince me to abandon it. There of course may be *another* line of reasoning, but not the one provided by Corvus.



We still don't have a single other person than Corvus who thinks that the 'Not P, then Not Q' line of reasoning is valid. We do have universities that say it's explicitly a fallacy.

I accept that you don't agree with cogito. I'm not trying to convince you of cogito.

You have expressed agreement with corvus reasoning - there are many people on this forum who see a problem in his reasoning, but you're the only one who thinks his reasoning is good, so we can talk about it.

His reasoning is based on going from "if I think, then I exist" to "if I don't think, then I don't exist". You've read the conversation apparently, so you can see him defending this throughout the pages - am I correct about that?

So the question many of us have is, where does "if I don't think, then I don't exist actually come from?"

Corvus has provided his logic for where it comes from. Where do you think it comes from? How do you, personally, Beverley, how do you go from "if I think then I exist" to "if I don't think then I don't exist"? Or, do you go to that at all? Perhaps you don't.

You've explained what Beverley thinks about it?

So it sounds like you're still not agreeing with what he just said, which is

Therefore if P-> Q, then Not P -> Not Q must hold. — Corvus

He's confirming it again - that denying the Antecedent is a part of his train of logic.

I want to make this clear, Beverley : I'm not overly concerned that you agree that the cogito is a bad argument. I'm concerned fundamentally with the reasoning used to get there. You said you agreed with Corvus reasoning, and this is a big part of corvus reasoning:

Therefore if P-> Q, then Not P -> Not Q must hold. — Corvus

I want to establish with you, before anything else, if this is a valid step in reasoning in your view. I'd like to be explicit about it, because if we can't get to the bottom of this, we can't get to the bottom of anything. Corvus says it's basic logic, and I agree, it's basic logic. If we can't get to the bottom of basic logic on a philosophy forum, what hope do we have to get to the bottom of anything?

And if you disagree with his logic there, that doesn't mean of course that you have to disagree with his conclusion. You can agree with his conclusion without agreeing with his reasons for getting there. If someone says "2+2 is 4 because I saw 5 guys jump Mickey mouse at Disney land", we can agree with their conclusion while still saying "your reasons for getting there are not good".

So would you mind trying to establish with me if its generally true to say "if P-> Q, then Not P -> Not Q must hold."? I would love to have this basic logic established, as it has so far been a fundamental part of Corvus reasoning to this point.

I would begin by questioning the soundness of accepting a principle such as the principle of parsimony. Why would a simpler theory be prima facie preferable? What virtues does it espouse over a more complex theory? — NotAristotle

This might be a completely wacky idea, but---

In the realm of the multiverse, simpler universes appear more commonly than more complex universes. This is true for multiverse ideas like Max Tegmark's Mathematical Universe or Stephen Wolfram's Ruliad - universes exist for all mathematical or computational structures. The reason simpler universes occur more often is because they occur in their simplest form, but then they re-occur because they can be re-specified in more verbose forms in more complex universes as well.

Obviously that's a completely speculative reason to believe in parsimony, but there's a way to make sense of it there.

He based his logic on the premise that you can jump from "p implies q" to "not p implies not q" in general. You can see him present the argument here.



He established that as the logical basis for jumping from "I think therefore I am" to "I don't think, therefore I am not."

You are agreeing with him and his reasoning, so I just want to establish unambiguously: do you think what he thinks, that for any "p implies q" type statement, "not p implies not q" must also be true? Do you agree with corvus on that one or disagree?

no. You cannot jump from 'I think therefore I am' to 'I do not think, therefore I do not exist'.

In general, you cannot jump from "p implies q" to "not p implies not q".

Do you believe you can jump from "p implies q" to "not p implies not q" in general?

"I exist" is an inference. "I must exist in order to think" might be an intuition, I'm not sure. I'm asking you what you think because I think you might be able to help me figure it out. I don't think you can help me without honestly expressing your own thoughts though, so that's what I want from you.

Would you please just honestly tell me, do you personally disagree with (a) your own existence, and/or (b) the idea that you wouldn't be able to think if you didn't exist? If you disagree with a and/or b, could you please try to clarify why?

if you find yourself no longer thinking, no longer doubting, or breathing, or you can’t find yourself anywhere anymore, you may have gone too far. — Fire Ologist

Or if you talk to some meditators, you've gone exactly where you should have. Though I'd agree with you, that's probably too far (except for a select few, who would probably benefit from mental non-existence - people for whom life is just complete needless suffering, for example, extreme chronic pain sufferers perhaps)

In specific they can choose someone well regarded by expert peers. — Bylaw

I think that would be a safe bet. Of course, the person bad at reasoning could only agree that that's a safe bet if one of the things he's bad at doesn't involve him completely discounting the expertise of others - if he's rejected even that, he's stuck in a limbo of bad reasoning forever. But if he has that - if he's capable of respecting the reasoning abilities of others, and of experts above all - then he stands a chance at discovering his own flaws and perhaps finding guidance to fix them.

He could even just delegate his thinking to another person. "I will believe whatever this person believes". If he's bad at reasoning, maybe he could resign himself to just stop trying, if that's possible. Probably not possible in his every day life, but maybe possible in the space of ideas - when he's pontificating on philosophy or science or whatever.

For one to think, one must exist. I think. Therefore, I exist.

The conclusion here of course isn't "Flannel Jesus exists", the "I" is a variable for the reader to place his own identity into it. This was a confusion that Corvus had - he would read the above and think I'm trying to prove to him that I exist. That's decidedly *not* the point of it - I'm sure you already know this, but I'm just making extra-sure. The conclusion I would want you to draw from it is not that "Flannel Jesus exists", but rather that Banno exists - and if Corvus was reading this, the conclusion I'd want him to draw is that Corvus exists. The "I" is a stand-in for whoever is doing the thinking - you do your own thinking, so you put your own identity into "I think therefore I am".

I've gone on about that for long enough, considering you probably already knew that, so that being said...

Would you please just honestly tell me, do you personally disagree with (a) your own existence, and/or (b) the idea that you wouldn't be able to think if you didn't exist? If you disagree with a and/or b, could you please try to clarify why?

If you want the Cogito to be the foundation of your enterprise, you will need more than intuition. — Banno

Which part of the reasoning process do you personally think is 'just an intuition'?

Of course.

Fascinating, this is the first I've heard of this test. Thanks for the link.

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. — Banno

In my conversation with Corvus, he himself has already agreed with the necessary intuition to agree with the Cogito - he has agreed that existence is required for thought.

If existence is required for thought, then "I think therefore I am" makes immediate sense, don't you think? If someone agrees that "I must exist in order to think", then the cogito becomes an obvious consequence.

I'm not trying to prove it to everyone, generally - mainly, I'm just pointing out that this guy's counter arguments do not hold. His main one is an explicit formal fallacy, denying the antecedent. It's a fallacy EVEN IF the cogito is incorrect - his conclusion being right or wrong is independent from his reasoning being explicitly wrong. The conclusion is of less interest to me than the reasoning used to get there.

Apprentice (verb). And for the mentor, a tried and true method of teaching — Bylaw

This thought occurred to me too, but with the following hesitancy: if this person knows he's bad at discovering truths and reasoning, how confident can he be that it's *true* that the person he's chosen as his mentor is *good* at reasoning? I mean, if this person is bad at reasoning it's probably pretty likely that just about ANY mentor might offer an improvement, but still, he might prefer to have a better mentor rather than a worse one - if his reasoning skills are compromised, it stands to reason that his ability to distinguish a mentor that's good at reasoning might also be compromised.

Yes, situations that give you real feedback that you have indeed made a mistake are amazing opportunities for learning. Unfortunately, it seems that in philosophy that "real tangible feedback of a mistake" is not always as accessible as it is in other circumstances.

To be honest, I've actually been thinking about this for at least months. Questioning myself has always been important to me - I would want to know if I was systematically bad at reasoning. I'm sure I'm wrong about many individual things, but am I systematically good or bad at the processes of reasoning? And if I were systematically bad, how could I know?

But you're right about the motivation - there was something in particular that brought this from just being a thing I've been thinking about, to making an actual thread about it. It's honestly an interesting case study. We can see it happening live! And I'm certain that my approach to it has NOT been optimal - certainly some things I've said that I'd like a do-over of.

We are emotional creatures who inherit most of our beliefs and capacities from the culture we are reared in. — Tom Storm

Some of us desire to not be so beholden to such limitations. Everyone is biased, yes, but I think it's pretty likely that, on average, people who TRY to be less biased probably ARE less biased. On average, of course, not universally - some people may try to be less biased and fail, for various reasons.

For example, it's not so unusual to find people who say "I was born into a culture where everyone believed such-and-such religion, and that anyone who doesn't believe that was damned. I realized that this theological lottery didn't make much sense, so I endeavoured to base my reasons for believing things on reasons other than the idea that I just happened to win the theological lottery by being born into this particular culture." I have a lot of respect for that thought process - where most people just accept those biases they inheret, *not everyone does*.

To disagree is not necessarily to identify a contradiction. It is harder to ignore a putative contradiction than it is to ignore a disagreement. — Leontiskos

That's sort of why I'm talking about systematic disagreements, rather than just raw disagreements. Like, if you believe in God, and maybe 80% of philosophers you come across disagree with you and 20% agree with you, that's not really a 'systematic disagreement', that's just normal disagreement within a contentious topic.

But, if one of your arguments for something you believe in is of a particular form, and *literally everyone* you come across says "this form of argument is fallacious, this step in your reasoning doesn't follow from your last step", then it's no longer just a standard disagreement on a contensious topic, it's something else. It's systematic.

Disagreement is to be expected, even when you have beliefs that are reasonable or even correct. Universal, or near-universal, systematic disagreement is presumably not.

Someone with understanding of both sides is in a much better position to adjudicate. It may be that that person never "gets out" of their bad reasoning, but we can for our part ignore them if they are unable to explain or understand. — NotAristotle

Someone bad at reasoning may see another person disagreeing with them, saying "this argument is poorly formed / fallacious", and decide that that person just doesn't understand their argument. "You just don't understand my argument" is an easy and readily available out for anything the poor-reasoner says.

it may be that reason can be instilled into this individual viz. interaction with other rational individuals. In that case, patiently correcting someone for their logical infelicities may be best. — NotAristotle

One can discover that they are bad at reasoning by bumping up against contradictions in their own thinking. This happens most obviously when others call them out on their contradictions — Leontiskos

Yes, this seems like an intuitive avenue to a discovery of one's own erroneous reasoning facilities to me as well, BUT it relies on one necessary premise that the person bad at reasoning must first accept - he must first accept that other reasoners systematically disagreeing with him about his reasoning is a sign that his reasoning is (or might be) wrong.

If they don't accept that premise in the first place - if one of the faults in their reasoning facilities is to completely ignore the possibility that other people systematically disagreeing with them might be a sign that those other people are correct and they themselves are incorrect - then this avenue of correction gets shut down. Do they become essentially stuck permanently thinking poorly, stuck with bad reasoning, if this avenue is shut down?

I suppose it's kind of recursive, this problem - if one of the benefits of being able to reason well, and use logic, is to find out what you're wrong about, then... what if you're wrong about logic and reason itself?

Don't pat yourself on the back too hard. True patience would actually involve *considering what the people you're talking to say*. You haven't begun to do that yet.

What you are saying always seemed so clear to me — Beverley

All of what he's been saying? Including his reasons for disagreeing with the cogito?

His central argument in this thread has been, if "I think therefore I am" is true, then it must also be true that not thinking implies not existing.

In other words, (p implies q) necessitates (not p implies not q).

Do you think this is good reasoning? For all p implies q, must it also be true that not p implies not q?

It doesn't need a logical ground — Lionino

Even if it did, he's already agreed with it prior in the thread. He agreed that someone has to exist in order to think. He just doesn't understand how that means "thinking -> existing".

Therefore I think therefore I am is a meaningless statement to the rest of the world — Corvus

This is the second time you've made it out like it's about other people - it's about yourself, not others.

It's "I think therefore I am", not "he thinks therefore he is".

https://en.m.wikipedia.org/wiki/Cogito,_ergo_sum

Descartes's statement became a fundamental element of Western philosophy, as it purported to provide a certain foundation for knowledge in the face of radical doubt. While other knowledge could be a figment of imagination, deception, or mistake, Descartes asserted that the very act of doubting one's own existence served—at minimum—as proof of the reality of one's own mind

Look at that last sentence - twice, it says "one's own". One's own existence, one's own mind. "I think therefore I am" is a statement for the speaker of that statement to understand as it pertains to himself, not to understand about someone else.

Your disagreements thus far have all been based on misunderstandings, misunderstandings of what the argument itself is about, and misunderstandings of basic logic like modus ponens.

I disagree with that. — Fire Ologist

Interesting.

He has told me that I'm incapable of understanding basic logic because I don't think (p implies q) implies (not p implies not q). I of course do not think that that means I don't understand basic logic, and I can't find a single source that agrees with him on that - and I've looked. He has looked to, and has come up short.

To the contrary, I think it's basic logic that you can't just jump from (p implies q) to (not p implies not q). I can find quite a lot of sources that agree with me on that.

if we're loose about what we mean by "certain" and don't mean "exactly 100% certain" then totally.

But if certain means perfectly 100% certain, no room for error, then it just seems immensely easy to think of things that could go wrong. One of my ex girlfriends had her middle name misspelled in her certificate - swapped a g for a j. If that's capable of happening, I find it very easy to imagine someone writing in a wrong date, swapping a 6 for a 5 perhaps.

And that's not even getting into the conspiratorial stuff.

If you feel certain, all the power to you. I just don't think so. I don't think it's fair to say, about this sort of thing, "there's absolutely no way anything on my birth certificate could be incorrect".

Here's what the real modus ponens looks like in the checker

https://www.umsu.de/trees/#((p~5q)~1p)~5q

That's affirming the Antecedent, which is how modus ponens really works.

Then we modify it to your denying the Antecedent variation

https://www.umsu.de/trees/#((p~5q)~1~3p)~5~3q

Invalid

If you want to use the logic checker correctly, here's how you do it. First I will demonstrate a valid argument, Modus Tollens

https://www.umsu.de/trees/#(p~5q)~5(~3q~5~3p)

Then, if we slightly modify it to your argument, which is that if you have p implies q, you can get not p implies not q, look at what happens

https://www.umsu.de/trees/#(p~5q)~5(~3p~5~3q)

Modus Tollens is a valid argument format. It is generalisable and applicable to any p implies q situation.

Denying the Antecedent is invalid. It is not generally true, it is not applicable to all p implies q situations. It is trivially easy for anybody to think of situations where it doesn't apply.

You have chickened out of every disagreement once it's starts looking like you might be wrong. Be brave. Look at the possibility that you might be wrong in the face. I dare you.