Advent calendar door #23: Freedom and physics
It's 11pm on a Friday night and I'm writing an article on free will. Did I decide to do this freely? Well, I've got a deadline and a tendency to obsession, but on the whole I'd say I did. I could just as well have joined my friends in the pub.
Most people would probably agree with me. Mental disorders aside, most of us think that we have the capacity to act freely. Our sense of morality, our legal system, our whole culture is based on the idea that there is such a thing as free will..
It's embarrassing then that classical physics seems to tell a different story. In 1687 Isaac Newton published his laws of motion, which describe the behaviour of all physical objects, from particles to planets. They tell you exactly how an object will move when it's given a push. And they say that no object will change its path without such a push. There's no effect without a cause and for every cause there's a unique effect.
Newton's remarkable achievement led to the idea, first proposed by Pierre de Laplace, that the Universe runs like a giant clockwork. "The idea is that if you know everything about the state of a system [for example the Universe] at a particular time and you know the forces that are operating on this system, then there is only one future course of events for this system," says Jeremy Butterfield, a philosopher of physics at the University of Cambridge. "It's dictated by the initial state and the forces operating on it." And if you accept that we are part of physical reality, then this means that our future is determined too. This leaves no room for free will or for moral responsibility.
Oh dear! So are we really mere puppets in a pre-planned history of the Universe? And how does quantum mechanics fit in? To find out read the full version of the article here.