reductio ad absurdum
noun /rɪˌdʌktiəʊ æd æbˈsɜːdəm/
/rɪˌdʌktiəʊ æd æbˈsɜːrdəm/
[uncountable, countable] (from Latin, philosophy)- a method of proving that something is not true by showing that its result is not logical or sensibleWord OriginLatin, literally ‘reduction to the absurd’.