According to the laws of physics, everything we do follows inevitably from what happened before – and yet we’re convinced we can change the world. Can we?


9 December 2020

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Are you predetermined?

WHAT are you doing right now? Reading these words. Why? Presumably because you chose to. Even if you didn’t – if you are encountering them years in the future lining a forgotten box of crockery in the attic, say – you can always choose to look away now. You possess the nebulous quality of human free will.

Nebulous because, despite debating it for millennia, philosophers have been unable to pin it down – and although we are pretty convinced we have it, at some level it must be an illusion, rather like our sense of self is (see “Are you always the same person?”).

Let’s start with the physics. Whenever you decide something, a certain pattern of neurons fires in your brain to turn your thought into action – moving towards the kitchen to make coffee, perhaps, or formulating an utterance you will come to regret. Ultimately, that is all down to pulses of electrons – fundamental particles that follow the cast-iron laws of physics, under which everything is determined by what happened immediately before.

That doesn’t leave much room for free will, apparently. “Physical laws, if they’re deterministic, tell me that everything that I do, everything that happens in the world, including everything that I do, including every decision I ever made, follows logically from the laws of nature [and] the initial conditions of the universe,” says philosopher of physics Jenann Ismael at Columbia University in New York. Since we control neither the laws of nature nor the initial conditions of the universe, we …