Nicholas Ferreira

This is the author's justification for the second and third premises (which is in the full paper linked above): Maybe this can clarify a little. Yes, ...

Thanks for mentioning that. How does it implies the existence of anything? Premise 2 simply says that for any x, if x should be done, then x can be do...

Well, the inferences made by the author aren't explicit, so I made a proof (which is kinda big) of of it and I changed 4 to "I believe in anything a"....

Oh, sorry, I forgot that. It means minimal free will. "The minimal free will thesis (MFT) holds that at least some of the time, someone has more than ...

Hmm, think I got it. So you are talking about a necessary condition, right? If P is a necessary condition to Q, then if you have Q, you also have P, b...

But you didn't say that non-condition is a condition. Your statement was "The state of being unconditional is itself a condition". Here, "condition" a...

Hmm, it's a hard sentence to translate... I thought that using definite descriptions we could have something like K((?x)(Sx?¬Cx)), with K(x) standing ...

Since 'a' is an individual, your use of negation is not the same as the negation of natural deduction, since the latter is a truth-functional operator...

Sure, but how would you define ?A without using ? or accessibility? In both cases the circularity would appear again.

Well, ok, but I couldn't find a precise formal definition/explication of 'possible' and 'accessible' without being required to already know one of thi...

So what it means for a world to be accessible to another?

He explains both concepts, as I said before. And he uses possibility to explain the accessibility relation.

No, I understand what it means for a proposition to be possible. The whole point is that Kripke explains it in terms of a concept (accessibility) whic...

Well, I don't think I've conflated accessible and possible, for me it's very clear the difference, and I agree with everything you said. But I still c...

Yes, in natural language it's ok to state that. But I want to know if ithere is any way of formalising that using logical or set-theoretical language.

Well, with ?p(p?¬p) I say that p?¬p is true for every proposition, because p is a variable, not a specific proposition, while ?(p?¬p) says that "p?¬p"...

I think a more adequate formalization would be ?x?y(?(Gyx??z(¬Gyz?z?x))), that it, for any x and y, is possible that (y is good for x and there exists...

Yeah, you're right, this is true. But, for Frege, the statement "the difference between A and B does not subsist" wouldn't be neither true nor false, ...

Oh, I thought it could be the case, but since english isn't my native language, I used a translator and thought that "begat" could be applied to both ...

Oh, yeah, misstype. Thanks!

Well, the problem is at the inference from 3 to 4. The contrapositive of a statement has its antecedent and consequent inverted and flipped. Therefore...

"Introduction to Logic", Irving M. Copi. - It was the very first logic book I read. It's kinda old, and treat some subjects like basic logic, language...

That's what I'm talking about! I just woke up, so I'll do some things and se your reply calmy later. Thanks for answering! Yeah, as I said before, I j...

Hmm, you are right, I expressed myself in the wrong way. Thanks!

Of course, but you were saying about the consequent only, not about the entire implication. That is why I said that in "P?Q", "Q", alone, permits "¬Q"...

I think I already answered it, but feelings and this kind of thing are something that were developed through the evolution of the species. I don't kno...

But why would the conclusion need to explicit something that already has been said in the premise? I mean, in "P?Q", for instance, if you analyze only...

Wtf are you doing on this forum? This is said in the antecedent, not in the conclusion. Maybe this image can help the visualization. https://image.prn...

If you had read what I said you would notice that the title isn't anything than a flashy title. Why does the conclusion permits "(x or y) or (x & y) t...

Are you reading anything i'm writing? I said at least twice that the "1+1=2" is absolutelly irrelevant to what i'm proposing, it's just a detail. The ...

Are you really saying that "(((?x)(Fx • ?(?y)(?y=x • Fy)) • (?x)(Gx • ?(?y)(?y=x • Gy))) • ?(?x)(Fx • Gx)) ? (?x)(?y)(((Fx ? Gx) • (Fy ? Gy)) • (?x=y ...

But you example was about bachelors. Anyway, it doesn't matter, the logical formula in question have variables, and I still not understanding the reas...

Well, I guess you are confunding logic tautologies with linguistic tautologies. In logic, a tautology is a formula, or a truth-function, that returns ...

Why not?. Monozygotic twins are genetically identical, at least during the early development (which doesn't necessarily have to do with the two twins ...

I don't even know what are you talking about. I'm leaving the post for those who want to test, and possibly improve, their logical capacity. Thanks fo...

Do you ask your teacher the reason to prove something on a test? Man, it's a challenge, I'm assuming that people who frequent this section of logic an...

Lol, what about interpretation? I'm not talking about mathematics foundings here neither about some philosophical trip. Actually, it doesn't matter if...

Of course it could exists, but as I said, infering it from the fact that science aparently can't explain this or that is a logical jump. And differenc...

First, humans cannot be reduced to a DNA code or something like this. The fact that monozygotic twins are genetically identical doesn't have to do wit...

Well... No. As you quoted, if A is false, nothing is said about B. But you need to notice that it is a existential claim. You are treating it like as ...

But the second premise in the argument II does not excludes the existence of robbers not being american. It says only that exists at least one robber ...

(?x) means "to all x", (?x) means "there exists an x", "?" means "implies" and "?" means "and". So, for instance, the first conclusion (?x) would be r...

Oh, of course. Ax := "x is american" Ex := "x speak english" Rx := "x is robber"

Well, you are just saying that truth is everything that isn't non-truth, which is circular, and as you said, even if it's a good definiton, you would ...

I don't know if I got it. Why isn't your example fallacious? I mean, why from "We like to be happy and not suffer" you can deduce "We ought to make pe...

I declared it to be both? I just said that AvB can be an "is" statement or an "ought" statement, then I showed an argument to be considered in each ca...

Nice, thanks for the explanation and the recomendation. I'm downloading the book and I'll read it. I read the summary and it seems to be very good. Ph...

Thank you for answering! I'll read the links you sent. Do you have any recomendation for me to go deeper on propositional logic (and also, what does "...

Hello. Well, in the books I read it didn't talk about this difference, and it seems, to me, that they are logically the same thing. But, intuitively, ...

Thank you! I totally forgot about making assumptions in the argument to build the proof. I took the way you made the first proof and modified a little...