The veil of ignorance: great thought experiment

John Rawls

John Rawls

What if we could get together to form a new kind of society … and we did not even know who we would be in that society?

This is a famous thought experiment, proposed by the Harvard philosopher John Rawls in his 1971 book, Theory of Justice.

Rawls was trying to justify democracy as fair as opposed to merely utilitarian (ie, “the greatest good of the greatest number”). How would we go about deciding what is fair? By imagining a situation that has never existed, and indeed can never exist.

Rawls called that situation the “original position”:

No one knows his place in society, his class position or social status, nor does anyone know his fortune in the distribution of natural assets and abilities, his intelligence, strength, and the like. I shall even assume that the parties do not know their conceptions of the good or their special psychological propensities. The principles of justice are chosen behind a veil of ignorance.

You have probably already grasped the power of the experiment. Normally, we think of justice with ourselves in mind. A single black mom in a public-housing project will have a very different view than a start-up entrepreneur in Silicon Valley or a trustafarian in prep school or a prisoner or …. you get the point.

But if we don’t know whether we will be tall or short, male or female, smart or dumb, lazy or ambitious and all the rest of it, we have to test every principle against the possibility that we might be the least advantaged member of society with respect to it.

A simple example: Slavery in 19th-century America.

Slave owners considered America free and fair and were prepared to go to war for that “freedom”. That’s because the slave owners assumed that they were, well, slave owners. Using purely utilitarian reasoning, they might have concluded that slavery produced the maximum pleasure of the greatest number of people (ie, the white majority) and was therefore right.

But if they had played Rawls’ thought experiment, they would have had to imagine that they might instead be slaves. Suddenly, slavery no longer looks so good.

Getting liberté, egalité, fraternité onto one flag


Now, some of you might remember that, back in April, I tried to figure out whether freedom and equality could ever coexist, as the naked-boobed Marianne (pictured) was clearly hoping. In that post, I was thinking about biology. But perhaps the answer lies in Rawls’ thought experiment.

As we imagine a society without knowing what role we have in it, we will certainly agree that it should be free, and that we should not sacrifice that freedom by forcing everybody to be equal.

But that leaves us having to imagine inequality, and, thanks to our veil of ignorance, we might be the ones ending up with the least (wealth, opportunity, beauty, power…). So how can we agree to inequality that is fair?

The answer is

  • First, that inequality must benefit even the least advantaged member of society (though obviously not in the same proportion). So we do not mind that the Sergey and Larry at Google get astronomically rich because even a single black mom in a public-housing project can now google where to get her baby a flu shot.
  • Second, that the cushy positions in society must be open to all.

Intelligence and talent, for those playing the thought experiment rigorously, would thus cease being mere boons for the individuals that are lucky to have them and instead become social resources that help even those who don’t have them.

I can immediately think of lots of things that we still would not agree on–inheritance taxes, say. But Rawls’ thought experiment definitely introduces even a certain amount of fraternité into the equation. Marianne would love him. For the power of this experiment, I’m hereby including Rawls in my pantheon of great thinkers.

Einstein’s unfinished thought experiment

Mark Anderson

Mark Anderson

As you know, I am fascinated by many aspects of Albert Einstein, and one of them is his habit of doing thought experiments. We don’t do those enough!

In Einstein’s case, he mused (picture him day dreaming) about things such as elevators falling through space and painters inside of them, about two-dimensional beetles crawling around three-dimensional wires, and so on.

But his most famous thought experiment has always bothered me. So I was delighted that Mark Anderson, a physicist who writes the Strategic News Service, which offers trend-spotting analysis, echoes my frustration in a recent newsletter. Here he goes:

The most famous scientific anecdote of all time remains half-done, unfinished, although countless authors have told the story of Albert Einstein as though it makes sense. Here is how the “thought experiment” goes: when he was 16 or so, Einstein decided that he needed to travel alongside light to understand its nature. (Drum roll.) In this way, he came to understand Special Relativity, a bit later in life. Wow.

There’s only one problem with this apocryphal story: Special (and General) Relativity talk about time and space. They don’t say a word about light, except as it responds to gravitational force.

So, none of us knows what Einstein saw (or did not see) of the light itself, as he (illegally) screamed along at the speed of light, looking sideways…

Well, I have been doing this thought experiment for a while now, without success. (That is not surprising since I opted out of physics as soon as I could in high school.) Here, by the way, is a cool illustration of it.

It always seemed to me that if I were looking sideways at a wave-like quantum of light going at the same speed, it should not even “exist”. Mark seems to think the same thing:

Waves, at their deepest origins, are relative. If you stand at the shore, in they come. But if you fly along with one, like a seagull – say, at the crest of a traveling wave – there is no motion at all; there is no wave.

Having said that, I remind myself, through the haze of my confusion about such matters, that Einstein’s Relativity ended up being about time as much as space.

So perhaps what happens to a light-beam rider is that time … stops. Which is, ironically, exactly what happened when I opened my email inbox this morning.

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