Picture: Libet. 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.


  1. 1. Fr Peter Jones says:

    he (or, more accurately, his brain) should have seen that coming.

  2. 2. Matt says:

    Ok, let’s try to put together a thought experiment that is in with a shout of being a real experiment.

    Materials: Libet’s ‘freewilled finger flicks’ Dennett’s (Goodman’s)’Phi’ insights.

    Recipe: first set up the neural activation detection setup with which Libet demonstrated that the precursors of a freewilled finger flick appear to occur before one’s awareness of making that choice.

    Next, wire the detection equipment up to a light via a variable delay – to allow for fine tuning.

    With a bit of tinkering you should be able to get the light to flash after the subject has committed to the finger flick but before they become aware of that commitment.

    Next, instruct the subject that they are to make free willed finger flicks at a time of their choosing – unless the light has come on.

    My assumption is that they would have a sensation of the light coming on, then choosing to flick and being unable to stop themselves.

    I guess you would have to retune the equipment as thy became ‘expert’ at that process – I wounder if you would lose the effect?

    Akrasia anyone?

  3. 3. Rusty says:

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