Posted: May 14, 2019 10:28 pm
TopCat wrote:If "Motte, hence Bailey" is false, then am I right that it doesn't follow that "Not Bailey, hence Not Motte"? I looked up Modus Tollens, which says:
If A, then B
Not B
Therefore not A.
However if B doesn't follow from A, then Not B doesn't (on its own) imply Not A.
In other words, just because they distract attention with an easily debunked Bailey, doesn't mean in itself that their Motte is also unsound. So it needs to be separately debunked?
I'm not an accomplished logician, so happy to be schooled here.
No, you are quite correct. However, that's kind of the point in it as a rhetorical strategy. The two propositions are only linked in the most superficial way; not in a way that would satisfy formal logic. Essentially, it's like a bait and switch. Non-acceptance of the desirable argument (the bailey) doesn't infer denial of the sound position (the motte) - that's really just a rhetorical flourish used by the proponent to either stump their interlocutor, or mislead an agreeable audience.
You could thereby deny that the two are linked - deconstruct the notional connection between the two, which would be fine. But then you're also actually being drawn into a tangential discussion which basically means the device has worked to some degree, and if you're not careful and precise, could give the proponent something to work with to continue that misdirection.
Alternatively, you can simply ransack the desirable ground, loot it for all it's worth. Basically mug them of all the ground they wanted to hold and draw them into sallying back out again.