Aug 21 2008

Free will?

Category: GeneralDave @ 00:25

I have seen a lot of discussion recently on whether or not human beings have “Free Will”. That is, they are able to make decisions based on information and opinions which are currently held within their brains. However, this begs the question of how such a thing might operate in practice.

I think that first of all it’s necessary to clarify what my definition of “free will” actually is. There have been whole books written on the subject by many people over centuries. However, most of them didn’t have the benefit of the knowledge of how the brain works that we currently have. My definition is something like this:

Free Will is the ability of an entity to make decisions based purely on information contained within itself.

I say “something like this” because I suspect it’s not the final version – and given that many intelligent people have spent so much time and energy on the question so far, it can’t be that simple! Or can it?

Some clarification is needed: “information” in this context includes knowledge and experience acquired by living, innate knowledge passed to it as part of its creation process (e.g. via genes) and knowledge passed to it by any other means which I haven’t thought of yet (and maybe no-one else has either).

For the moment I’m going to leave aside any idea of he existence of a “soul”, “conciousness” or other component which is outside of conventional science. If we do this then the only game in town is that free will is exercised by the physical brain. The brain is a biological mechanism which is subject to the laws of chemistry which, in turn, are subject to the laws of physics.

To explain the next bit I’m going to have to delve into some fairly esoteric physics – but don’t leave just yet! I’ll keep this very simple and apologise to those amongst you who are biologists, chemists and/or nuclear physicists. This will be a dramatic simplification but, hopefully, accurate as far as it goes.

The brain consists of cells. The ones which do our thinking are called neurons. Each neuron is connected to lots of its neighbours. They exchange information by sending tiny electrical impulses along these connections. The impulses are generated by electrochemical reactions – which is another way of saying chemical reactions which involve an electrical current. At the receiving neuron the tiny current that arrives triggers another, equally tiny, chemical reaction. In order for us to reach a decision on something a huge number of these tiny reactions must take place.

For simple decisions there will be a majority of the neurons involved coming to the same conclusion. However a really difficult decision may rest on which way a single neuron goes, as the others are equally divided.

A few more definitions: An atom is the smallest indivisible particle of an element. Elements are things like hydrogen, gold and sulphur which cannot be broken down further. Two or more atoms joined together form a molecule. Now an atom has a core (nucleus) with a cloud of electrons in orbit around it. When atoms group together in molecules, they share electrons – their individual electron clouds merge. A molecule can have from two to tens of thousands of atoms in it and, of course, they are not all necessarily of the same element. The air we breathe contains oxygen – but in the form of a molecule which contains two atoms of oxygen. A grain of salt contains many molecules of sodium chloride, each of which contains one atom of the element sodium and one of the element chlorine. It also contains water which helps the sodium chloride to form crystals. A water molecule contains two atoms of hydrogen and one of oxygen – hence the well-known “H2O”.

If two molecules which can react together are in close proximity and the conditions for them to react are borderline (it can depend on temperature, the presence of other molecules, etc), then whether they actually react or not is governed by quantum physics. Quantum physics is, to most of us, just plain weird. It makes predictions which seem totally counter-intuitive but which are born our by observation. When electrons form a chemical bond between two molecules (there are other types of “thing” that do this but they all work the same way), they undergo a quantum state change.

So, at the extreme, the decision-making could come down to a single molecule within a brain neuron reacting or not reacting with another molecule. Whether this reaction goes ahead or not is down to the behaviour of the electrons which link the two molecules which, as I have said, is governed by the laws of quantum physics.

There is uncertainty within the scientific community of what governs certain aspects of how particles governed by quantum laws behave – particles such as electrons. Their behaviour is either precisely predictable according to a set of laws we have yet to find or it is partially or fully random.

Assuming that the brain operates according to currently understood physical laws and at the lowest level decisions are effected by quantum state changes, I see two possibilities:

  1. Such state changes are governed by a mechanism which is truly random. Essentially, the final act in a decision being taken is governed by a chemical reaction. the outcome of which is random – there is no way to predict if will be “yes” or a “no” (or “steak” or “fish”).
  2. Such state changes are governed by a mechanism which is not random: each follows inexorably from what went before, starting from the Big Bang.

In case (1), we do not have free will – what we decide is mostly predetermined but is also heavily influenced by random events when very “fine” decisions are to be made.

In case (2), we do not have free will – what we decide is totally predetermined.

In both cases (1) and (2) we have the illusion of free will but not free will itself. (However, the illusion is for most people and all practical purposes good enough.)

So if science has the whole story on how the brain works, this inexorably leads to the conclusion that we do not have free will. Furthermore, it doesn’t matter if the mechanism is part way between the two described above – for example pseudo-random rather than true random.

But… either of those two mechanisms meet the requirements of my definition of free will, so there must be something missing in the definition.

If I add that free will must be governed neither by a random process nor a deterministic one (at the quantum level) then what are we left with?

Nothing!

At least, not that I can see. Free Will would have to be based on some other mechanism of which we currently have no knowledge (and some might categorise as “supernatural” or “spiritual”).

So, we may have free will but it is difficult to accept the mechanism. However, just because we don’t yet know how it happens doesn’t preclude finding out in the future.

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