When it comes to "armchair economics," a popular and effective technique is the reductio ad absurdum. Rather than attacking a view head-on, it is often simpler to take the argument to its logical conclusion, at which point its inherent fallacy is obvious (or at least, should be obvious).

Robert Murphy likes to use a reductio ad absurdum when it comes to international trade, and the widespread fear of "cheap imports." When arguing with someone along these lines, he first asks, "So are you saying that it would it be better for the US if foreigners shipped us expensive imports?" This usually causes some hesitation. Then he follows up with what is, in his opinion, a zinger: "So if cheap imports are bad, does that mean foreigners would really be hurting us if they shipped us goods for free?" This question makes something click for many people, because no matter how much they've read about domestic job destruction, they still harken back to the childhood truth that it is good to receive presents.

A recent article in The Observer forced him to go back to the drawing board. Click here to read the story.

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