For Fun

Reductio ad Absurdum

June 30, 2009

Do you remember debating current moral issues in social studies class in high school? It consisted of a question starting with "to what extent should" or "be it resolved that", and asking students to put forth their opinions on the subject.

I always took great enjoyment out of these questions. It was exciting to take a controversial moral issue, boil it down to its fundamental point, and then devise a general moral rule that, if followed, would resolve not only the issue at hand, but also other issues that share the same fundamental problem.

Or at least, that's how I approached these questions. And it was thrilling to debate these issues with friends that had a similar approach. Sometimes my friends and I would disagree over what the fundamental problem was. And other times, we would agree on the problem but disagree on what principle would resolve it. I remember having many debates like these that stretched well into the night.

However, as much as I enjoyed these questions, there was another class of people that simply were not interesting to debate with. The teacher was almost inevitably one of them. There was always a point in the debate where it became impossible to bring up any more arguments, and the conversation would suddenly die. I finally realize that "reductio ad absurdum", or rather the rejection of it, is the cause of it.

Reductio ad absurdum, means "to reduce to absurdity". And while I see it as a valid reasoning tool, it is generally taught in school as a logical fallacy. For example, if I were to make the statement "all wrongdoing should be punishable by death", then you could make the retort "then by your reasoning, a child who fibs to his parents should be sentenced to death". You have successfully argued against my statement by demonstrating that my rule, if applied consistently, leads to absurd conclusions. Realizing the absurdity of my statement, I would be forced either to retract my statement, or specify the bounds and conditions on when my statement would apply.

However, I was frustrated to discover that this method of reasoning was not acceptable in school. Whenever I challenged my teacher on his statements, the reply would invariably be some form of "well you can't simplify it that far", or "it's not black and white like you make it sound", or "you have to use your own judgement. You must judge on a case by case basis".

Let us analyze exactly what "judging on a case by case basis using your own judgement" means. It means that the rule does not apply in all circumstances, each case could be different. And also that there isn't even a rule for judging when it can and cannot be applied, that you must rely on your own "judgement". Well, what if my "judgement" doesn't agree with your "judgement". Who should we listen to? Well, in North America, we side with the view that's been around for longer, known in legal terms as the "Law of Precedent". Or we side with whomever shouts louder (ie. the Squeaky Wheel Syndrome). Or we side with the better looking (contrast the fight for the preservation of Panda bears versus the preservation of Hirudo leeches). So "using your own judgement" essentially amounts to no rule at all. The moral rule may be followed when it is convenient, and handily dismissed when it isn't. By allowing your own judgement as a clause, the rule is no longer a regulator of your actions, but a justification of your actions.

And of course, this is also why the debate dies at this point. By rejecting reductio ad absurdum as a valid argument, by stating that it's perfectly alright to have a rule with unknown, unpredictable, and disputable exceptions is synonymous with declaring that logic and reasoning is invalid. And how could anyone hold a logical debate without reason?


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