Reductio ad absurdum as Legal Argument

By means of the reductio ad absurdum or apagogical argument a thesis is argued showing that its denial has absurd implications because it leads to a contradiction. The argument has different variations, and it is more or less conclusive, depending on its inner logic and on the justification of the premise whose denial is regarded as absurd. This paper discusses the typology and some of the specific problems shown by this argument in legal reasoning, particularly its logical nature, its relation with the ideal of coherence or the legal order, its vicinity with consequentialist arguments and its emotive and potentially fallacious character. Moreover, several examples of use of the argument in the motivation of legal decisions are offered and classified.