yeah I edited my post as you were writing that, I realize that's what you mean

So (B∨¬B) is False, it is always the case that ¬B. — Lionino

I just saw this in your post above and classically that's not how logic goes. B v ~B is true even if we know the answer is ~B

I kinda see what you were going for but I don't think the symbolic logic application made it work properly, which is I guess what you're saying here

https://thephilosophyforum.com/discussion/comment/917298

cool program dude

Honestly it just doesn't seem like he gets it. He says the debate remains, but to everyone else it's really clear.

A sometimes tells the truth, but he's lying in this case. No ambiguity about the answer, it's clearly solvable in just a minute.

I'm personally amazed that he's made such a simple riddle last 3 pages, when nobody else has any question about what the answer is.

this is no general trump conversation, this is the highest profile and closest assassination attempt in a long ass time! It deserves its own thread.

However, reading (A implies notB) as "something other than B (caveat: also) follows from A". would be consistent with "B follows from A", because it would not deny that B also follows from A. — Janus

Yeah that's a good explanation for why it intuitively makes sense that they're a contradiction.

Consider this as an intuitive explanation for why they aren't a contradiction:

A implies B can be rephrased as (not A or B)
A implies not B can be rephrased as (not A or not B)

Do you think (not A or B) and (not A or not B) contradict?

You edited your posts after reading the arguments of Michael and Igitur :lol: — javi2541997

For the record, I did in fact edit exactly one post, but I edited it within a minute of making it and it had nothing to do with the arguments of Michael and Igtur - I had already made my initial answer, which was entirely the same as theirs, back at the very start of page 1.

The only post I edited was this one: https://thephilosophyforum.com/discussion/comment/917024 I slightly misworded something, and I edited it very shortly after posting.

yeah, scenario 1 is the more obvious one, scenario 3 was what you came up with with the alternative interpretation of sometimes, and scenario 2 is what I was offering as another alternative.

just to be fully clear:

You're saying "I sometimes tell the truth" and "I always tell the truth" can be simultaneously true - which I brought up in the second comment in this thread, I get the idea.

You're saying, that means A and B could both always tell the truth, and C always lies - that's good, that's one possibility.

Another possibility the is, A sometimes tells the truth and B always tells the truth. Test out the validity of everyone's statements in that case and let me know what you think.

yes I'm actually talking about the same interpretation, and what I'm saying is a possibility within that interpretation

Or one of a and B sometimes, and the other one always tells the truth

I didn't edit my posts. What edit do you think I made?

ok you must be trolling at this point

The answer is apparently obvious to everyone but you.

Because you claim A can’t be a liar emphatically. — javi2541997

I think you're confused about what I've claimed. I've only claimed he can't be THE liar, as in, the one who always lies. He can lie, I've said that explicitly

Person c always tells the truth, and he says B is the liar. Therefore a can't be the liar. I can't tell if you're trolling.

A can sometimes tell lies, but he can't be the person who always lies.

Am I missing something in that attempt to use logic? — javi2541997

Yes, you're overcomplicating something very simple. C tells the truth. C says B is the liar. Therefore, B is the liar.

But I was wondering what happened to A. — javi2541997

You keep asking this, and everyone else keeps giving the same answer. A sometimes tells the truth.

Some claim he is ambiguous, others he is contradictory. — javi2541997

Who claims these things? As far as I can tell, everyone here except you has understood that b must be the liar. Who else do you see claiming a might be the liar?

I don't know why you're defending that. If C always tells the truth, and C says B always lies, then B always lies.

That seems pretty simple and straight forward to me. Which part of that logic do you disagree with?

But that's not the context. A doesn't always tell the truth. So... why are you saying that's the context? We know he can't be the one who always tells the truth, because that would lead to a contradiction.

No, B is the ambiguous person given the ambiguity of the phrase "I sometimes tell the truth". — Michael

He's using unclear wording, but when he says "ambiguous person" he means "the person who sometimes tells the truth". He doesn't mean "the person whose role is ambiguous".

according what context? No b couldn't

you've just laid out two scenarios we already know aren't the case. I'm not really sure what the point of assuming they are the truth tellers, when we already know they can't be the truth teller.

Assuming either one of them is the truth teller leads to contradiction, so we don't.

do you think it could be some other way?

I've been saying that consistently since my second post in this thread, yeah

Then B is always false and ambiguous — javi2541997

No, just false

But what happens to A? — javi2541997

He sometimes lies, and sometimes tells the truth.

if we know c is the truth teller, and c says b is the liar, then b is the liar. Easy as that.

A sometimes tells the truth, and his statement in this riddle just happens to be a lie. Presumably one can imagine a has told the truth at some other occasion.

okay, then if they're mutually exclusive, we can use the following logic:

B definitely CANNOT be the guy who always tells the truth, since that would make Bs statement about himself a lie

A definitely CANNOT be the guy who always tells the truth, since that would mean B always tells the truth, which we know is false

That only leaves C as the guy who always tells the truth

The rest naturally follows.

I'm not sure you answered my question. Can you give me a yes or no?

But if "b always tells the truth" and "b sometimes tells the truth" are interpreted to be mutually exclusive statements, the riddle has an immediate solution.

C tells the truth
B is the liar
A sometimes tells the truth

If they aren't mutually exclusive there's another possible answer (maybe more than one)

Person A claims person B always tells the truth.
Person B claims person B (himself) sometimes tells the truth.
Person C claims person B always lies.


Secondly, I want to solve this riddle. Who is the liar? — javi2541997

When person B says he "sometimes tells the truth", is that consistent with the statement "person B always tells the truth"? I just want to get that question clarified first, because it could be a weird technicality - when he says he sometimes tells the truth, is he saying he's definitely not the guy who always tells the truth?

Because there's an interpretation of "sometimes" that's consistent with "always". If "some" just means more than one, then "always" counts as a possible validation of "sometimes".

I'm not saying "the material conditional in Boolean logic used for computing is nonsensical".

The consequent follows from the premise in the implication, (A -> B)

You think when I use the word 'follow', and completely understandably, I mean "this thing is true". As in, I'm saying "B is true" period.

I'm not.

"follow" can also just be a synonym for implication. A -> B, From A follows B. If you assert A, B follows.

I can say "A -> B" without asserting B, and in the same vein, I can say "From A follows B" without asserting B. Because they're just different ways of phrasing the same thing.

I'm not asserting B. I'm asserting A -> B. You have to see the difference to understand. When you understand how I can assert A -> B without asserting B, you can understand how I can say "From A follows B", without me saying "B is true".

no - the consequent can only be affirmed as true IF the antecedent is first affirmed as true. It's THAT that is not the case here.

I'm not affirming the antecedent, so I'm not affirming the consequent.

I don't know what you think I'm saying, but I feel like you're misunderstanding it.

Of course I agree that we can't conclude B and notB. The fact that you're saying that makes me think you've misunderstood what I said.

You're certainly not alone in thinking that,

But I personally think it's not a coincidence that "from falsehood, anything follows" perfectly mirrors how, if you phrase "A -> B" as "from A follows B", then if A is false, you can say "A -> anything", from A anything follows.

I don't think that's a coincidence at all. I think the principle of explosion is actually really relevant here. But I understand that not everyone sees it that way.

Right, I do have some familiarity with logic gates. Are any of those useful logic paths nonsensical? Genuine question... — Janus

Well... yes, kind of.

From falsehood, anything follows. Have you ever heard of this? This example before us is a great example of that.

You think if a then b, and if a then not b contradict each other.

Many other posters think they don't contradict each other, BUT with the caveat that if they're both valid statements, A must be false.

If a is false, and "from falsehood, anything follows", then (if a, then anything) fits. Replace anything with b, replace it with not b, replace it with a snail with a tophat, replace it with à̶̙̦͔́̀b̴͈̼̞̓͘y̵̝̣̳̲̟̤͑̏̈́͝ş̷̭̼͖͓̼̈̿̈́͐͐̃̕ș̶̡̲̘̯́́̋̄͘͜ä̵̉̓͊̋͜l̸̯͛̀̒̕ ̷̞͎͔̱͛̕d̴̪̬̻̠͕̋̃͗̾̉ẹ̴̪̭̌̒͝ś̷̢̢̢͔͉͎̄̿p̸̨͎̘̼̬̼͇̓͌̊ā̵̢̤̗͌i̴̡̤̹̘̰̿͜͝r̴͉͙̣̍̂̈́̓̄̚...

As long as A is false, "if a then anything" obtains. You can verify this with the truth table. And this is where your sense of nonsense comes in. Do you see?

Yes, I think I have lost this debate to Tarskian. — fishfry

You haven't lost any debate, you just made a post with some mistakes. You seem ready to acknowledge them, which is winning in my book.

The sentence, Gödel proves the lack of determinism of deterministic systems, even sounds contradictory. — Tarskian

It's kind of hilarious, it seems like you're using this as an example of some unavaoidable language landmine just about anybody could walk into, but... it's not, it's just another landmine YOU personally chose to walk into.

Like, we're in a sitcom and you see a landmine on the ground and you just actively, knowingly step right on it, and your leg blows off a hundred yards away, and you look right in the camera and the Curb Your Enthusiasm music plays and you say "Damn, these landmines are so hard to avoid."

They... aren't that hard to avoid. You're literally not trying.

Looks like the answer to both is, you.

The sentence, Gödel proves the lack of determinism of deterministic systems, even sounds contradictory. — Tarskian

And who came up with that sentence? Typed that into google, no hits. Is that one of yours?