I am looking for a phrase or idiom that means roughly like "reductio ad absurdum". Specifically, taking an otherwise logical argument to irrational length, that it starts to look logically absurd.

The intent is to get the meaning out in a more understandable way without using too many words and also not to use latinzed phrases as my audiences are not versed with it. I am not sure if "Overkill an argument" can be used in such situations.

  • Who is your audience? Teenagers? Maths graduates? Sociologists? Native speakers of English?
    – James K
    Commented Apr 8, 2020 at 8:59
  • I'm voting to close this question as off-topic because obviously if English did have a common equivalent to “reductio ad absurdum”, we wouldn't all be using that Latin phrase. Commented Apr 8, 2020 at 16:54

2 Answers 2


In mathematics "Proof by contradiction" is a more modern way of saying "reductio ad absurdum"

You can also just use "... which is absurd!" You can just use a literal translation.

However if you want the full flavour of the Latin phrase, then just use it. It is quite common to use Latin expressions in English, E.g. "Quid pro quo" or "et cetera" (and e.g. is also Latin).

An audience that is aware of the various types of logical proof is more than likely to know the Latin phrase. If they don't know the Latin phrase, they you are going to have to explain "proof by contradiction" anyway. So you may as well just explain the Latin phrase (which is pretty easy, because the words are clearly recognisable from their English cognates.)

  • I think there's a different focus on the usage of "Proof by contradiction" and the common usage of "Reductio ad absurdum", where people commonly use to mean that it's being applied fallaciously. (vs Proof by contradiction, as a (valid) technique to say that if Not X is impossible, X is true.) Commented Apr 8, 2020 at 11:08
  • Reductio ad absurdum is a valid method of reasoning. If you are using it to mean some kind of fallacy then you are mis-using the phrase. logicallyfallacious.com/logicalfallacies/Reductio-ad-Absurdum
    – James K
    Commented Apr 8, 2020 at 11:13

Take a look at slippery slope and straw man arguments. These are types of (fallacious) arguments where someone takes an idea to an absurd extreme in order to discredit the idea. Is that what you are looking for?

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