Nothing says that we may not substitute A for φ and ~A for ψ. Hence, we may. Indeed, that's kinda the point.
But this is trivial stuff! Why don't you already know this? — Banno
No, it's the DEFINITION of 'modus ponens'. — TonesInDeepFreeze
Modus ponens doesn't require that a conditional is not contradictory, nor that the "major" premise (which must be a conditional) is not contradictory, nor that the "minor" premise (which might or might not itself be a conditional) is not contradictory, nor that the premises together are not contradictory — TonesInDeepFreeze
You're confused. I'm not "equating" A -> ~A to A -> B.
Let P and Q be metavariables over formulas. Then modus ponens is any argument of the form:'
P -> Q
P
therefore Q
Instantiate P to A. Instantiate Q to ~A. There is no restriction against such an instatiation.
So
A -> ~A
A
therefore ~A
is an instance of modus ponens. — TonesInDeepFreeze
It's where you disagree with the definition of 'modus ponens'. — TonesInDeepFreeze
If P is false, then P -> ~P is true. — TonesInDeepFreeze
Then you'd argue incorrectly — TonesInDeepFreeze
That's wrong.
If A is false then "If A is true then A is false" is true. — TonesInDeepFreeze
It's a valid argument with a necessarily false premise and so is necessarily unsound. — Michael
But my point is that one of the ways doesn't require appealing to explosion or even contradiction since the argument is in the form of modus ponens. — TonesInDeepFreeze
If so, can you say which premise is false and why? — NotAristotle
3 follows from 1 and 2 by modus ponens. — TonesInDeepFreeze
1. A -> not-A
2. A
Therefore,
3. not-A. — NotAristotle
I’m posting that video here because I think it challenges us to re-consider what constitutes language. To what extent is an immediate relationship with our non-human surroundings a language? — Joshs
There is no purpose. — Michael
So we accept that not only is a zygote's "right to life" not absolute but also that their lives are worth less than other things (even things other than something's life). We might disagree with how little/much a zygote's life is worth, but at the very least we must accept that "we ought not terminate a pregnancy because the zygote has an absolute/overriding right to life" is false. — Michael
A lot of people I have encountered who pontificate about the 'sacredness of human life' are simple hypocrites. They're quite comfortable with capital punishment and don't seem to mind if the poor die in vast numbers through lack of affordable services. — Tom Storm
That presents the opportunity to explain that the life of a zygote has less moral weight than the woman's bodily autonomy. — Michael
As the article notes, it seems a lot like the electoral college system. I place both of them under the classification of “seemed like a good idea at the time.” — T Clark
Referendum and initiative SOMETIMES lead to very bad law, and sometimes to very good law. — BC
You have this "democracy" now, and in fact, the President and expesically the Senate use their powers for serving the financial aristocracy ("300 familities"), they have the full power and do not allow other people to become their competitorr; and it is becomes clear that smart people are not allowed to become presidents in US, because a smart president can become a threat for the power and money of these people. — Linkey
Natural rights are enforced by nature, but not necessarily in a timely fashion — frank
Antigone was Jewish? You learn something every day. — Banno
For what it's worth, Jewish law:
Scientists in the study of human origins place a lot of significance to burial of the dead. I've never thought through what that really means. — frank
am asking you why you believe that a zygote does not have the same fundamental right to not be killed when innocent like a woman does; and you refuse to engage — Bob Ross
Bob Ross has dragged the discussion back to essentialism again. "It's human, so you mustn't kill it", ignoring capital punishment and war and euthanasia. — Banno
Crop milk isn't from a maary gland. — Benkei
even bachelors are not as analytic as we like to pretend it is. But hey, everything frays at the edges of language. I'm not too worried about it. — Benkei