Robert Nozick's Argument Against Pure Pleasure

On pages 42 to 45 of Anarchy, State, and Utopia, published in 1974, Robert Nozick described a thought experiment with an unusual structure. "Suppose there were an experience machine that would give you any experience you desired," he wrote. Float in a tank, neuroscientists at the controls, and your brain receives a stream of indistinguishable-from-real experiences — love, achievement, adventure, a great novel written by you. You don't know you're plugged in. The pleasure is perfect.

Would you connect for life? Nozick was sure most people would refuse. He used the refusal as a knockdown argument against ethical hedonism, the view that pleasure is the only thing that matters. Three things explain the no, he argued: we want to actually do things, not just have the experience of doing them; we want to be a certain kind of person, which a tank cannot make us; and we want contact with a reality independent of our own minds.

For about 35 years that was the standard reading. Then in 2010 Felipe De Brigard, a philosopher at Duke, ran the experiment as an experiment.

He asked 72 undergraduates a slightly different question. Imagine you are already inside the machine. You discover the truth. There is a button to disconnect and return to your real life — which is described to you in advance. The version of "real life" was randomized: ordinary, maximum-security prison, or wealth in Monaco. The framing did most of the work. When the real life was prison, only 13% disconnected. In the ordinary and wealthy versions, around half stayed plugged in.

What people do when they refuse Nozick's machine, on this reading, is prefer whatever they already have. Status quo bias, dressed as a moral argument. The machine is still a useful test. What it measures is not allegiance to reality. It is allegiance to the life one happens to be living.