“If people stand still on escalators, then why don’t they stand still on stairs?”

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Evolutionary psychologists offer some fairly odd accounts of the intersection between gender and behavior, see e.g. this, this and this, but when it comes to getting things utterly, ridiculously wrong, economists can sometimes give them a run for the money, which is why this essay in Slate by Steven E. Landsberg from August of 2002 is so wonderfully hilarious. Below is an excerpt:

…If people stand still on escalators, then why don’t they stand still on stairs?

It was observed early on that if you stand still on stairs, you’ll never get anywhere. But for reasons I can no longer entirely reconstruct, that explanation was dismissed as overly simplistic. Soon the search for a deeper theory was under way. Within a few days, blackboards all over the economics building were covered with graphs and equations. Research projects were temporarily shelved while we tackled the escalator puzzle, which had taken on the dimensions of a profound and perhaps insurmountable challenge to economic theory.

For those of us who were too dense to see what all the fuss was about, one of our colleagues spelled out the paradox: Taking a step has a certain cost, in terms of energy expended. That cost is the same whether you’re on the stairs or on the escalator. And taking a step has a certain benefit:it gets you one foot closer to where you’re going. That benefit is the same whether you’re on the stairs or on the escalator. If the costs are the same in each place and the benefits are the same in each place, then the decision to step or not to step should be the same in each place.

In other words, a step either is or is not worth the effort, and whatever calculation tells you to walk (or not) on the escalator should tell you to do exactly the same thing on the stairs.

And so one of the world’s top economics departments entered a state of near paralysis. Theories were presented, considered, and rejected; I will spare their inventors (including myself) the embarrassment of having those theories recounted here. Suffice it to say that each theory centered around one or another cockamamie reason why “marginal analysis”:the weighing of costs and benefits associated with taking a single step:might not apply in this situation.

For a bunch of economists, that’s a pretty radical position since we use marginal analysis to explain how people choose everything from the lengths of their workdays to the number of chocolate-chip cookies they have for lunch. (What is the cost, in terms, say, of calories, of one additional cookie? What is the benefit, in terms of deliciousness? If the benefit exceeds the cost, have another! Otherwise, it’s time to stop.) …

Via Yet Another Sheep, where a competeing solution to the condundrum posed in the title of this post is offered.
–Ann Bartow

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