(also known as: reductio ad absurdum [misuse of], slippery slope fallacy [form of])
Description: Erroneously attempting to make a reasonable argument into an absurd one, by taking the argument to the extremes.
If X is true, then Y must also be true (where Y is the extreme of X)
There is no way those Girl Scouts could have sold all those cases of cookies in one hour. If they did, they would have to make $500 in one hour, which, based on an 8 hour day is over a million dollars a year. That is more than most lawyers, doctors, and successful business people make!
Explanation: The Girl Scouts worked just for one hour -- not 40 per week for a year. Suggesting the extreme leads to an absurd conclusion; that Girl Scouts are among the highest paid people in the world. Not to mention, there is a whole troop of them doing the work, not just one girl.
Don’t forget God’s commandment, “thou shall not kill”. By using mouthwash, you are killing 99.9% of the germs that cause bad breath. Prepare for Hell.
Explanation: It is unlikely that God had mouthwash on his mind when issuing that commandment, but if he did, we’re all screwed (at least those of us with fresh breath).
Exception: This fallacy is a misuse of one of the greatest techniques in argumentation, reductio ad absurdum, or reducing the argument to the absurd. The difference is where the absurdity actually is -- in the argument or in the reasoning of the one trying to show the argument is absurd.
Here is an example of an argument that is proven false by reducing to the absurd, legitimately.
Big Tony: The more you exercise, the stronger you will get!
Nerdy Ned: Actually, if you just kept exercising and never stopped, you would eventually drop dead. There is a limit to how much exercise you should get.
Tip: People very often say stupid things. Sometimes it is easy to reduce their arguments to absurdity, but remember, in most cases, your goal should be diplomacy, not making the other person look foolish. Especially when dealing with your spouse -- unless you really like sleeping on the couch.