The only things I know about basketball are that Wilt Chamberlain was seven feet tall and that he scored a hundred points when he led the Philadelphia Warriors to victory over the New York Knicks in 1962. I know these facts because Chamberlain is a central figure in the seminal work Anarchy, State and Utopia by the American political philosopher Robert Nozick.

Nozick invites us to imagine a world that we think is perfectly just. But then Chamberlain appears, and we all have the opportunity to watch him play. Chamberlain insists that he will only take to the court if everyone puts 25c in a special box marked “for Wilt Chamberlain”. Over a season, a million fans consider 25 cents a small price to pay for this pleasure, and so his box contains a quarter of a million dollars. The fans who put their money in Chamberlain’s box are happier, Chamberlain is richer, and people who are not interested in basketball are in the same position as before. If the distribution before Chamberlain was just, how can you dispute the justice of the distribution after Chamberlain?

There are some practical problems about this story, but these do not concern great philosophers. Nozick wishes to argue that justice can never be defined by reference to the distribution of outcomes – which is what those who present egalitarian arguments try to do. Any such just outcome could, and would, be upset by voluntary transactions whose effect might be inegalitarian but which left everyone better off. Traders, celebrities and business people might struggle with Nozick’s philosophy but they love his conclusion. He offers a principled rationale for the claim that the outcome of a market process is not only efficient but just. Fairness should be judged by access to opportunity, not by the perceived fairness of the result.