Think: Reason

Free Will & Determinism

This topic came up the other night while I was having dinner with my father in law, and I wanted to write down my thoughts on this.

My position goes a little something like this…

The universe follows a set of physical laws. Four of them actually: strong nuclear force, weak nuclear force, electromagnetism, and gravity. Theoretical physicists think that just before the big bang all of these forces were combined into one super force. Einstein spent many years trying to figure out how to combine all of these forces to come up with his theory of everything.

Getting side tracked, but the bottom line is that all physical matter in our universe follows these physical laws. These physical laws are deterministic. That’s why they’re laws. These laws are “descriptive” not “prescriptive”. I choose (I’ll get to my use of the word choose later) to obey the law of man regarding murder, that’s a prescriptive law. Gravity describes how objects react to one another, they’re descriptive laws, they’re explaining what happens.

Now… when we say “I choose to do x”, what do we mean by “I”? Is it my foot?, no. How about my elbow? no. I think most of us would agree that our brains do the “choosing”. So what happens physically when I “choose” to do something? Well, there’s a bio-chemical reaction in the brain that takes place that sends an electrical signal to my muscle that causes it to move. Those bio-chemical reactions are a part of the physical universe and thus subject to the same descriptive, deterministic laws. Hence, humans are physical matter and also deterministic.

Imagine a being that at any given point in time can take a snapshot of the universe. It knows every particle in existence and how they will react to one another. Using the physical laws of the universe, such a being could predict the next moment in time to a certainty. This type of being is commonly referred to as a “Laplacian Being” named after Pierre-Simon Laplace who hypothesized this type of being he said:

“An intelligence which at a given instant knew all the forces acting in nature and the position of every object in the universe – if endowed with a brain sufficiently vast to make all necessary calculations – could describe with a single formula the motions of the largest astronomical bodies and those of the smallest atoms. To such an intelligence, nothing would be uncertain; the future, like the past, would be an open book.” – Pierre-Simon Laplace (quoted in The Fascination of Physics by Jacqueline D. Spears and Dean Zollman (1986))

Take for example a coin flip. A coin flip can either go heads or tails, we flip a coin because we perceive this as “chance” it could go either way… 50/50. However, this is only considered “chance” to us because we do not posses all the knowledge of our Laplacian being. If we were able to determine the amount of force exerted on the coin, the wind resistance, how many times it flipped, etc, etc all the way down to the atomic level, we would be able to predict with certainty if that coin was going to fall heads or tails every time. In other words, it’s subject to the laws of physics and hence deterministic even though we perceive it as “it could have gone either way…” Which actually… it couldn’t.

Having made this conclusion one might make the statement:

“If we live in a deterministic universe, the future is inevitable, and thus we have no free will”.

I think this is wrong though. What do you mean by “inevitable?” Well, “evitable” means “avoidable”. So the future is unavoidable? What future? The future is going to happen whether we live in a deterministic universe or not. “Avoid ability” is something done by an entity that has the ability to try and predict what that future may be if they don’t act regardless of what future will or won’t be.

One of the great things about humans is that we’ve developed a very good “avoid ability” simulator in our brains. We have the ability to run a simulation in our head to try and determine what the outcome of an event will be if we do or don’t act. We don’t need to whip up a batch of liver and onion ice cream and taste it to know that it won’t taste good to most humans. We can run the simulation in our brains and come to this conclusion. Humans in other words have the ability to look forward into possible futures and react.

If I were to throw a brick at your head… the light would bounce off the brick, hit your eye, the eye would send eletrical signals to your brain your brain would run it’s simulation quickly.. “if I duck X is likely to happen, if I don’t duck X is likely to happen”, and then most would say you “choose” to either duck or not duck. I’m suggesting that no “choice” is made. When we say “you” decide, again we’re talking about your brain. Your brain doesn’t “choose” to do anything… it just does. It does what it’s going to do based on the physical laws of the universe. There is a reason that it did what it did. Again… if we could be that Laplacian being for that moment, we could quantify all the things that caused that brain to do what it did. Perhaps it just wanted to avoid the brick because it knew it would cause damage, perhaps that brain was looking for a court settlement… bottom line is… There’s a reason, a deterministic reason based on the physical laws of the universe.

So… do we have free will? If you mean, do we have the ability for choice… I suppose, if by choice you mean an entity’s ability to predict a possible future and attempt to avoid it. Do we live in a deterministic universe? Yes. Are these two ideas compatible? I believe so.

What do you think?

(I should cite that I pulled a large portion of this argument from a few lectures by Dan Dennett. I happen to agree with his take on this… mostly. )

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A friend of mine thought I should elaborate a little bit more on the free will part of this piece. So here goes…

Let’s go back to the coin flip. The coin is just an object, it’s physical, it only moves because other physical objects move it. An object, acting upon other objects. I’m putting forth the argument that our brains are exactly the same. Their part of the physical universe and hence part of those laws which govern everything in the universe and thus, deterministic.

If we were able to give the coin the ability to shift it’s weight from one side or the other so that the coin could attempt to alter whether or not it came up heads or tails, would it then have free will? Many would say yes, because it can “choose” to attempt to come up heads each time. But what part of the coin would be choosing? It would have to have some apparatus that actually does the choosing. That apparatus would be physical and part of the deterministic universe.

The coin has the ability for choice but the part that does the choosing is physical and hence deterministic.

Think of the brain as a processor… a processor in a computer is not “smart”. It just computes ones and zeros. It’s all the programing that gets processed that makes the computer “smart”. Lots of things contribute to the programming of humans. Genetics, environment, etc. Bottom line is… a brain is going to do what a brain is going to do. The only way to influence that is to influence it physically (because it’s a physical object in our deterministic universe). But you can get the brain to act upon itself.

Take for example, eyesight. When you see something, it’s not the eye that’s seeing it. The eye automatically sends electrical signals to your brain. Your eyes are automatically physically affecting your brain. Same for all your other 4 senses. These senses are constantly firing off electrical signals to your brain to be interpreted. Pulling our laplacian being back in we can deduce that such a being would be aware of all of those electrical signals and how it would affect how that brain responds. The question though is… did that brain make what we perceive as a “choice” during that physical process?

We’re saying the words, “I chose”, but in reality “I did” is more appropriate. So again… if you’re referring to the human’s ability to make what we would perceive as a choice as “free will” then yes, we have free will (the only kind of free will that really matters if you ask me). but if you’re describing free will as some sort of non-physical, non-deterministic “thing” that is only bestowed upon humans… I would disagree.