It is the most mysterious answer I have heard in the forum, I am afraid. :DBecause it is obvious. — Lionino
No Lion. Posting picture of a logic book is not a philosophical process. It is unnecessary. Our linguistic discussions and reasonings should be able to lead us to some sort of conclusion. I was going to explain everything again in detail, if you only let us know what you meant by you said thousands of times, but you were again telling untruths there.No. Go post that picture of a logic book you were talking about. And also translate my phrase to propositional logic. — Lionino
I cannot make the folks to see the light, who are determined not to see it. — Corvus
I would love to know who he can make see the light. One person who thinks (a -> b) leads to (~a -> ~b) as a general rule. I'd love to have a conversation with that person. — flannel jesus
It is not a general rule at all. — Corvus
Oh, fascinating. That's not what it sounded like when you called it Modus Ponens, because Modus Ponens is indeed a general rule. — flannel jesus
So you don't think it's a general rule, meaning you think there are scenarios where you can have an implication, a implies b, and yet not have the implication of (not a implies not b), is that right? — flannel jesus
t's a shock to me that you call it modus ponens, which is a general rule, and then say now that it's not a general rule, without ever explicitly acknowledging that the thing your'e doing is in fact not modus ponens. — flannel jesus
a -> b) -> (~a -> ~b) is not modus ponens, we can both agree on that now. Fantastic progress. — flannel jesus
(~a -> ~b) is an assertion or inference against (a -> b) — Corvus
One of the ways it can be done is applying the contradictions to (a -> b), — Corvus
One of the ways it can be done is applying the contradictions to (a -> b), and check if it is true or false with the reality. — Corvus
It is not, these two are not mutually contradictory. One translates to (a∨¬b) and the other to (¬a∨b). Both are true if a and b are true. — Lionino
A→B ↔ ¬A∨B
¬A∨B ↔ B∨¬A
B∨¬A ↔ ¬B→¬A = ¬A -> ¬B ? — Corvus
If this proof were valid, A→B would always imply ¬A → ¬B - that's what I call a "general rule". — flannel jesus
So here already, it is clear that you have mistaken the very start of the point (a -> b) leads to (~a -> ~b) as a general rule. It is not a general rule at all. — Corvus
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