There is a lot of discussion whether free will is possible in the world where all events are determined by physical laws. Let’s stop and meditate on the word determined. What does it mean? It seems to mean that if we knew the current state of a system with coordinates and momenta of all atoms and molecules, we should be able to know also the state of the system in n seconds from now. There are too many ifs here, don’t you think? First of all, the system must be closed, i.e. confined to itself and isolated from external influences. This implies not only that the system cannot exchange particles with the outside world, but also energy (heat, electromagnetic radiation, or whatever other forms of energy there might be). That’s quite impossible. We might not even be aware of all forms of energy out there considering the “dark matter/dark energy” problem. We also must know the state of each and every atom in this closed system. One atom in the system or coming from outside with unknown state can throw all determinism out of the window.
Just look at the image above. Can we practically determine the position of every ball after the cue ball hits the pyramid? The movement of every ball is strictly determined by the Newton’s laws. What seems to be the problem? The problem is that we do not know the exact trajectory of the cue ball, where it hits the pyramid. We do not know the exact alignment of the balls in the pyramid (I am not talking about any quantum principles here). We do not know how every fiber of the table cloth and every microscopic groove in the table will affect the trajectory of every ball. We don’t know if all balls are exactly spherical, whether their mass is equally distributed, how many scratches and imperfections they have. We don’t know if the table is leveled or tilted to one side. So, OK. Trajectories of the balls are strictly determined by the Newton’s laws (if we ignore relativistic effects). That’s what makes this game possible. But how much is anything “determined”?
And that was a fairly idealistic environment. Reality usually looks more like this, except the balls are in Brownian motion.
Determinists say that every event is caused by another event. Let’s stop and meditate on the word caused. What do we mean by that? Causality is nothing more than another mental construct. It’s a way to describe relationship between events. In certain cases, when one event follows another event, we say that event 1 caused event 2. But it’s simply a special kind of connection between events. Which we construct in our mind. The relationship needs to follow certain rules outlined by Hume (e.g. event 1 must happen prior to event 2, event 2 must always follow event 1, etc. — Hume lists 8 attributes of causality) After spending the last 15 years of my career analyzing “failure root cause” of semiconductor circuits, I realized that that there is no such thing as “the root cause”. Finding “the root cause” comes down to finding practical and reliable ways of achieving desired results. Some ways are better than others and some results are more desirable than others. When a car “accident” happens, we can say that it was caused by distracted driving, slippery road, poor visibility, condition of the car, the tree standing in the way, etc. All of those can be considered as causes of the accident. But there is no magic that determines “THE ROOT CAUSE”. It’s possible to say that the tree caused the accident because if the tree were not there, the accident would not have happened. We can even blame evolution that “caused” the tree to exist. But it does not make any practical sense. I know the cause of all plane crashes — gravity. Is this the cause people look for?
We also seem to have freedom to pick and choose the causes of events:
To complicate the matters, an observer is a part of the observed system and inevitably affects the system’s behavior. Think of turning on the light to see what’s going on in the dark room. What will you see? You will see what’s going on in the room right after you turned on the light, not what had been going on in the dark. In some cases observer effect can be neglected, in some cases, not. So, the very act of inquiry into natural causes of events adds an element of free will to these events. Some things seem to be there just because we look. There is a Russian proverb “If I knew where I fall, I would put some straw there”. Knowing that an event will happen can change that event.
Now, let’s stop and meditate on the words physical laws. What are they? Aren’t they also mental constructs allowing us to describe the world and make useful predictions? Most physical laws operate within a certain idealistic model of the world and ignore “second-order” effects. What constitutes a “second-order” effect depends on the application. We can ignore relativistic inaccuracies of Newton’s laws when we play billiards, but when we design a GPS system, we have to take them into account. When we launch a satellite, we account for the mass of the Earth, perhaps, the Moon, perhaps the Sun. How about the effects of the gravity pull coming from the billions of distant galaxies? Probably, not so important. But second-order effects do exist even if we choose to ignore them. And we never know when they become too large to ignore. We also cannot pretend that we know all physical laws. There are a few that we happen to know. But I’m certain that there are quite a few of them that we are not even aware of. Determinism seems to be just another such idealistic model of the world which only makes sense for certain applications, but not others.
Anything left from determinism that has not been reduced to absurdity yet? Good luck with determinism, Mr. Harris and Mr. Coyne.
- Do we have free will?
- Laplace’s Demon (Wikipedia article)
- Causal determinism (Stanford Encyclopedia of Philosophy)
- A survey of attitudes towards quantum mechanics among scientists