Rawls’s Argument for the Two Principles

Rawls’s official argument is that the parties in the original position would prefer his principles of justice to utilitarianism. Since the decision by the parties in the original position is guaranteed to be fair, Rawls maintains, the fact that they favor his principles shows that those are the principles of justice.

Today we discussed Rawls’s case for thinking that the parties would choose his principles. Next time, we will talk about his reasons for thinking they would reject utilitarianism.

In the end, the two days come to pretty much the same thing: his case for thinking the parties would take his principles is that they would prefer them to utilitarianism.

Choosing the best worst

The core of Rawls’s case is that the parties will prefer his principles over utilitarianism if they look at the worst possible outcome under each set of rules. That is, they should compare social systems by looking at the worst possible lives under them and choose the system with the best worst outcome. This is the essence of the so-called maximin rule.

To make his argument work, he needs to explain why the parties should give that much weight to the worst possible outcome. Why shouldn’t they take all of the other outcomes into account too? After all, we do not normally make decisions based solely on comparisons between the worst possibilities of the alternative courses of action we are faced with.

Rawls maintains there are three features of the decision to be made by the parties in the original position that make it rational for them to focus on the worst possible outcome.

  1. They cannot estimate the probabilities of being in any particular social position: they don’t know how likely it is that they are in the worst position, the middle, or the top.
  2. They do not care very much about getting more than they could get in the worst position in a society governed by Rawls’s principles.
  3. They find the worst position in a society governed by utilitarianism to be unacceptable.

I said we would talk about the point about probabilities next time.

I also said that I did not know how we could determine whether the second point is true. Rawls himself says that he will supply the argument for this conclusion in a subsequent part of his book. Since it is very long and relies on detailed psychological theories, we do not have the time to assess it.

My own opinion is that the parties cannot really know that the people they represent do not care much about getting more than they could get in the worst position in a society governed by his rules. There are lots of people who want lots of different things in this world. Maybe you think anything less than a state religion is intolerable; people are willing to blow themselves up for this reason, after all. Or maybe you want to be an entrepreneur who would chafe under the restrictions on economic liberty in a Rawlsian society. Everyone does care about having more than the minimum, after all. Who is to say that many people do not care a lot, especially if they think that, but for the rules of society, they could make their standard of living significantly higher?

The third point

Rawls’s best argument, in my opinion, is that the parties know the people they represent would find the worst possible outcomes under utilitarianism unacceptable but that they would not find the worst possible outcomes under Rawls’s principles unacceptable.

The point is pretty simple. Utilitarianism could allow almost anything: slavery, medical experiments, summary executions, you name it. If it could be needed to bring about the greatest overall good, utilitarianism would have to be for it. So the worst possible outcome under utilitarianism is pretty icky. By comparison, the worst possible outcome under Rawls’s principles is pretty nice: extensive protection of personal liberty, equal opportunity, and a significant guaranteed income.

Given that the choice is between utilitarianism and Rawls’s principles, why run the risk of being made a slave, a subject of medical experiments, or the rest? That’s a pretty good question, in my opinion.

We will, obviously, return to this next time. One thing to think about is why utilitarianism would ever allow slavery or the other horrible stuff. What does life have to be like for that to be an option for a utilitarian?

Key concepts

  1. Why Rawls says the parties in the original position would focus on the worst possible outcomes.
  2. Why he thinks they would prefer his principles to utilitarianism.


Rawls, John. 1999. A Theory of Justice. Revised edition. Cambridge: Harvard University Press.


There was a handout for this class: 24.RawlsTwoPrinciples.handout.pdf