The Science of Discworld II

recursive dependence of prophecy upon people’s responses to it, unlike most of the other kinds of thing that we say, relates back to our facility with our own made-up little futures, the stories that we tell ourselves. They confirm us in our identities. It is no wonder that when someone – an astrologer or Nostradamus, say – pokes his finger into this mental place where we live, and inserts some of his own stories, we want to believe him. His stories are more exciting than ours. We wouldn’t have thought, going down the stairs to get a train to work, ‘I wonder if I’m going to meet a tall dark guy today?’ But once it’s been put into our minds, we smile at all the dark men, even some quite short ones. And so our lives are changed (perhaps in quite major ways, if you are a man doing the smiling) as are the stories that we ourselves proposed for our futures.
    This way that we react, fairly predictably, to what the world throws at us, casts doubt on our otherwise unshakeable belief that we get to choose what we do . Do we truly possess free will? Or are we like the amoeba, drifting this way and that, propelled by the dynamic of a phase space that cannot be perceived from outside?
    In Figments of Reality we included a chapter with the title ‘We wanted to have a chapter on free will but we decided not to, so here it is’. There we examined such issues as whether, in a world without genuine free will, it would be fair to blame a person for their actions. We conclude that in a world without genuine free will, there might not be any choice: they would get blamed anyway because the possibility of them not being blamed did not exist.
    We won’t go over that ground in detail, but we do want to summarise the main thrust of the argument. We start by observing that there is no effective scientific test for free will. You can’t run the universe again, with everything exactly as it was, and see if a different choice can be made second time round. Moreover, there seems to be no room in the laws of physics for genuine free will. Quantum indeterminacy, seized on so readily by many philosophers and scientists as a catch-all explanation of ‘consciousness’, is the wrong kind of thingaltogether: random unpredictability is not the same as choosing between clear alternatives.
    There are many ways in which the known laws of physics could offer an illusion of free will, for example by exploiting chaos or emergence, but there is no way to set up a system that could make different choices even though every particle in the universe, including those making up the system, is in the same state on both occasions.
    Add to this one rather interesting aspect of human social behaviour: although we feel as if we have free will, we don’t act as if we believe that anybody else has. When somebody does something uncharacteristic, ‘not like them’, we don’t say ‘Oh, Fred is exercising his free will. He’s been a lot happier since he smiled at the tall, dark stranger.’ We say ‘What the devil has got into Fred?’ Only when we find a reason for his actions, an explanation not involving the exercise of free will (like drunkenness, or ‘doing it for a bet’) do we feel satisfied.
    All of this suggests that our minds do not actually make choices: they make judgements. Those judgements reveal not what we have chosen, but what kind of mind we possess. ‘Well, I never would have guessed,’ we say, and feel we’ve learned something that we can use in future dealings with that person.
    So what about that strong feeling that we get, of making a choice? That’s not what we’re doing, it’s what it feels like to us when we’re doing it, just as that vivid grey quale of the visual system is not actually out there on the elephant, but an added decoration that exists in our heads. ‘Choosing’ is what our minds feel like from inside when they’re judging between alternatives. Free will is not a real attribute of human beings at all: it is merely the quale of judgement.
    1 Admittedly, many African tribes think no such thing: you can hide things from the fairly simple local god. But then it’s not much of a god. Probably the tribal mores have been corrupted with the passage of time.
    2 Why birth , the sheerest accident during our development’ Why not fertilisation? Or hatching from the zona pellucida , the egg