And much debate has nothing to do with deducing conclusions from an agreed-upon set of hypotheses at all. A lot of it is about offering different sets of hypot

And much debate has nothing to do with deducing conclusions from an agreed-upon set of hypotheses at all. A lot of it is about offering different sets of hypotheses and evaluative criteria, and attempting to convince others to adopt the starting point of your reasoning, not its final conclusion. There's also a lot of useful metadata that gets communicated via "fallacious" argumentation: the intentions and credibility of the speaker, alignment of incentives, presence of alterior motives, etc. This is all entirely appropriate, especially - as in politics - when the debate is about an ought rather than an is.