If everything is predetermined, free will must be just an illusion. Why then should we bother thinking about ethics at all? One answer is: If everything is predetermined, we do what we have to do. But such an answer does not encourage further discussion.
Over the past 60 years, the argument has changed. The meaning of free will is still obscure, but as a way of viewing the world, determinism has had to be discarded. The branch of science known as "quantum mechanics" has produced persuasive evidence that the world just does not work that way.
You've seen the inside of a clock, haven't you. It's complicated, but by looking at the way all the cog wheels fit into each other, you can work out what every part of the clock will do until the spring runs down. Do you think the world is just like a huge clockwork machine?
Charlotte: No way. The world is much more complicated.
Yes, but I want you to forget about how complicated it is, and think about how one thing leads to another. What if we could somehow find out what every single thing in the world was doing at (say) 2 o'clock this afternoon. Certain cars would be travelling along roads, and their drivers would have certain thoughts in their heads. Some of the cars would be heading for collisions. Storms would be gathering above some cities, and if we knew exactly how big the clouds were, we would be able to tell how much rain would fall.
Owen: But very trivial events can eventually have large effects. We learnt at school that if a butterfly flaps its wings in Africa, this might cause a storm on the other side of the world. [Owen had been learning about the concept of a "chaotic system". For information on this, see for example Gleick's Chaos, at page 8.]
OK. But suppose we knew absolutely everything about the world at 2 pm - where each butterfly was and what it was doing; exactly where each particle of dust was lying - everything. Could we then perhaps work out what would happen next - at (say) 1 second past 2 o'clock this afternoon?
Owen: You wouldn't know what everybody was thinking.
No, but suppose you did know.
Owen: Well, I suppose if you knew absolutely everything about the world, and if you were smart enough, you could work out where things were heading and what would happen next.
Charlotte: Nobody could be that smart.
That's right Charlotte, but we're pretending that someone could be.
Now can you see what I am getting at? If we can tell what will happen at 1 second past 2, then in principle we can tell what will happen at 3 o'clock, and even later. In other words, the world is like a clockwork machine, and if only we knew all about everything in the world now, we could work out everything that would happen in the future. This is what some philosophers and scientists used to think. It's called the principle of "Determinism".
Charlotte: They must have been pretty dumb.
Owen: But nobody would be able to work out what I was going to be thinking in the future.
Well you could say that thoughts are part of the whole system. These philosophers would have said that if your present thoughts, and every other fact about the world at present, could be known, then your future thoughts could be calculated, just like everything else.
Owen: That would mean that I'm not really making any decisions at all; I only think I am.
That's right. The philosophers and scientists I mentioned before would regard you and your thoughts as just a cog in the big world machine.
Owen: I'll stop bothering with anything then. There's no point. I'll just wait and see what happens.
If you like. But as you've already said, if those scientists and philosophers are right, you haven't really made a decision at all. You only think you have.
Owen: You said the philosophers used to think this way. Don't they still?
No. Nobody believes in determinism any more. This is an area of philosophy which has been very much influenced by experimental science. Scientists have found that the world just doesn't work in a deterministic way. Unfortunately, you'll find that the scientific discoveries don't help much on the question of whether you are really free to make decisions after thinking about things. But you might be reassured to learn that the world does not operate like a complicated clock.
Owen: But why wouldn't it? Everything must be caused by something.
That's exactly what philosophers used to say. But this is a scientific question. And you can't resolve scientific questions by arguing about the way things ought to be. The way to solve a scientific question is to do experiments and discover the way things are. Even scientists haven't always understood this important point. For centuries, scientists assumed the sun rotated around the earth, because since the people on earth were so important, that was thought to be the way the universe should be set up. Finally, everyone had to accept that the universe was not set up specially to suit the vanity of human beings. In the same way, we now have to accept that the assumption that a given situation must lead to a particular outcome - the principle of determinism - is simply wrong.
Owen: But how do you know it's wrong?
The facts of the matter emerged in the nineteen twenties and thirties. Scientists doing experiments on atoms and other small particles found that the behaviour of small particles could only be explained if they abandoned the idea that the speed and position of particles were separate and distinct properties which could be separately measured. They had to face the peculiar fact that if a particle's position was known with great accuracy, its speed could only be specified as being within broad boundaries. This introduced a random element into the motion of particles, and meant that the mechanical view of nature had to be abandoned.
Owen: But what if the measuring instruments were improved?
It isn't a problem of inaccuracy in the measuring instruments. The problem is in the way the universe works.
Owen: I don't understand why the world would work that way. It doesn't seem to make sense.
You're not alone. Nobody understands why or how, but scientists all accept that this is the way things are.