Reducto ad absurdum
The process - much beloved of stand-up comics and newspaper columnists - in which a proposition is disproven by following its implications logically to an absurd conclusion. Basically, going "what's going to be next, eh?" after a controversial or divisive suggestion is made. For example, the way that The Last Kiss attempted to persuade the audience to sympathise with male characters who abandon pregnant partners and have affairs with 23-year-old students led to Mark Kermode asking if a movie was on the way that would try and make us feel sorry for a serial killer because it was just someone dealing with a crisis.
(In actual fact that movie already exists, and it is called Driller Killer.)