Blind Reasoning

[Cogito]

This may seem inappropriate... But is anyone else even slightly amused by this argument? I hope it keeps going...

[aleph_0]

For their sake, I hope this is a very bad joke indeed.

[intellectualammo]

So there must be one and only one thing that counts as victory. Get him to write Q.

Our friend may just be rightfully recalcitrant in not writing Q. I don't think that you can ever have Q as a conclusion, as in the modus ponens form, because it is the consequent of the conditional P --> Q and is inseparable from it's antecedent, P. What I view the modus ponens form doing, is trying to make our consequent Q a conclusion, when it cannot be done. It can't be separate, right?

This is the only way that I can see why he is not accepting/writing Q. Seen this way, if all the above is correct, then I couldn't write Q either, it's not just him, or some sort-of evasion on his part...

Al_zero, what do you think of this?

[aleph_0]

Why would you be unable to assert "Socrates is a mammal"?

Consider that I show the tortoise 'Socrates is a man' on a board, and 'If Socrates is a man then Socrates is a mammal' below it, and I say, "This is what it is to apply modus ponens:..." and I draw a line under the lowest sentence and write 'Socrates is a mammal'. That's what modus ponens means is simply that, in any situation where you have the two sentences of the above form, you write the consequent separately. The question of whether this preserves truth when put into symbol form has been in debate here, though I cannot for the life of me understand why, but it is clear as day that it does. And so the symbolization of any given sentence P, where it is stipulated that P is only a sentence of the true variety (for we must acknowledge that there are sentences which reflect reality and those which do not, and so the class of true statements is a perfectly intelligible class of things); and (speaking somewhat inaccurately) it is stipulated that P --> Q means that in all situations where P is true, Q is also true; and it is also stipulated that P --> Q is only a sentence of the true variety; and since the formalization of modus ponens in general is the practice of moving from the circumstance where P is true and P --> Q is true, Q is then derivable, and since the general conditions are met in this particular case, Q is then derivable.

I'm not sure how closely you have been following the conversation, but in post #14 of the other topic titled Blind Reasoning I gave another explanation of this fact in slightly less rigorous terms. If this has not been fully satisfying, you may want to check that out.

[Edit: Changed first sentence because I forgot to add in the antecedent of the second single-quoted sentence.]

Edited November 28, 2006 by aleph_0