Benjamin Libet

By Peter Hankins

I’ve just heard that Benjamin Libet died at the end of July. His famous experiments remain surprising and controversial, and in fact I remember discounting them altogether when I first heard about them. It must have been in about 1985, I think: we were sitting on rickety chairs in the trademark squalor of Gordons Wine Bar, and I was giving the company the benefit of what I supposed were my more sophisticated views on the subject of free will.

“That’s all very well,” said a young scientist, “But there’s this bloke who’s proved experimentally that free will does not exist… Libet, I think. I was reading about it last week.”

“That sounds interesting,” I said, “But I don’t think that’s possible in principle. Freedom is not an observable physical property, so the issue is beyond the reach of empirical methods. Perhaps you’re thinking that free will requires some kind of causal discontinuity, but that isn’t actually the case.”

“Well, these experiments show that the decision to act is made before we become aware of it. That proves our conscious thoughts about the decision don’t determine which way it goes.”

“I don’t really see how you could determine experimentally when a decision is made, other than by asking the experimental subject,” I said, “It’s not as if you can read off the contents of someone’s mind from an encephalogram.”

“I’ll get you the reference.” he said -- alas he never did, and it was some years before I got round to mitigating my ignorance of Libet’s experiments. Libet himself seems to have been a thoughtful, complex man, very far from the gung-ho debunker I had at first envisaged.

Whatever the fate of Libet’s theory about a conscious mental field, his experiments are surely classics in the field and guarantee him a permanent place of honour in its history.

Peter Hankins is author of the Conscious Entities weblog.