In an argumentation where speaker A suggests an idea, we sometimes encounter this kind of fallacious proof from speaker B that speaker A's idea is bad (a very common form is known as passive-agressive behaviour of speaker B):
— I think that P is true.
— Yes but then it would make Q true. And you see, since Q is true, then [... long discussion... ] ... then it's absurd. Thus P is a bad idea.
in such situations, speaker B usually goes very briefly on the the fallicious implication
P => Q...
... but speaker B spends lots of time to describe how Q is bad, and thus the initial idea should be rejected.
What is the name of this kind of unpleasant proof?
This is usually disappointing for at least three reasons:
- speaker A who generally didn't imply Q at all in his idea, sees the debate moving from discussion about P to a discussion about Q's drawbacks (even if, in an objective manner, P and Q are not really linked-to-each-other).
- speaker A has the burden of proving that P and Q are unlinked, and the debate has then moved to something else than the original idea P
- in such situations, anyone could be easily fooled by speaker B (except speaker A who studied the initial idea in detail and has the big picture in mind)
TL;DR: is there a name for this: speaker A suggests an idea P, speaker B fallaciously moves from P to Q, and demonstrate how Q is bad, instead of refuting P directly?