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Richard Fulmer's avatar

“Sometimes it is simply better to make a rule”

Economist Mike Munger has an amusing thought experiment that demonstrates your point.

Imagine that you’re driving through a small town and you get pulled over by a police officer for driving through a green light. The officer explains that, in this town, people take social justice seriously, and they’ve realized that traffic lights are unfair.

Someone having to wait for a red light to change may have far more an urgent need to get through the intersection than the people sailing through on green. The townspeople have therefore decided that everyone must stop at every traffic light regardless of the color and compare their needs. The person that everyone agrees has with the most urgent need will go through the intersection first.

Munger, while admitting that traffic lights are arbitrary and, therefore, unjust, observed that they speed traffic flow for everyone. Having to stop at every light and discuss who should go first would make travel slower for everyone, including those with the greatest need.

While this experiment is silly, it actually has a practical application. In Hawaii, there are narrow roads with one-lane bridges (e.g., the “road to Hana”). The “fair” way to cross each bridge is to let one northbound car cross, then a southbound car, then another northbound car, and so on. The problem is that this scheme, while more fair, is very slow. An unwritten rule has evolved that speeds traffic considerably. Instead of alternating cars crossing, alternating *lines* of cars cross. A whole line of north or southbound cars cross the bridge at one time, while the cars on the other side wait their turn. Less “just,” but much faster.

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ssri's avatar

On a 1990's trip from the US to England, we had occasion to witness a similar situation, but with an automated scheme for controlling the traffic flow so groups of vehicles could use the single available lane in turn. Instead of two humans with radios and Stop/Slow-Go signs at each end of the controlled passage, they set up red/green traffic lights on a timer. I found that to be a marvelous idea, instead of wasting money on two people doing altogether too simple a task.

I am sure there are situations where this approach is suboptimal, but it seemed to work very well when I saw it in operation.

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dmm's avatar

In other words, ‘to everyone according to their need’. Seems I’ve heard that somewhere before...

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