Free will: on Physical Determinism

In my previous post in this series, I tried to get the definition of “free will” sorted out. To sum things up, I concluded that although the phrase “free will” is too ambiguous to be used without bringing up certain issues, it does have a core meaning around which all discussion on the matter revolves, that meaning being the freedom from external necessity–the idea that our choices are made by us, not forced onto us by external factors.

Having clarified that, I want to say some things about incompatibilism, the idea that determinism infringes on “free will”. The idea is a very common one in the free will debate–most people I’ve seen participating in such debates seem to agree with it–but does it actually hold water? What is the argument for it being impossible for us to make our own choices if determinism holds true?

Since I am most familiar with physical determinism–the most popular form of determinism currently–I’ll only be addressing the arguments for physical determinism being incompatible with “free will”; other forms of determinism, such as theological determinism, I don’t feel qualified to comment on.

Now, in my experience the basic argument for this physicalist incompatibilism goes like this:

“If everything is physical then our decision-making process must also be physical, located somewhere in the brain of course; and if all physical things can only behave in a specific way, which is dictated by the laws of nature, then our decision-making process and thus our decisions must be determined by our brain acting according to the laws of physics, not by us.”

The logic may seem sound at first glance–it certainly seemed that way to me at first–but a deeper examination reveals that the argument is based on two unstated and unproven assumptions, both of which contradict one of the argument’s premises.

In the first place, the argument assumes that the physical decision-making process is something separate from us–that we are not the brain. But if we are not the brain, then what can we be? Are we a disembodied mind? If so, that contradicts the premise that all things are physical, which is the basis for the entire argument.

If we’re to assume that physicalism is true, then we must be consistent about it, and so we must assume that we are something physical as well, in which case the brain must surely be a part of us, and if the brain is a part of us, saying “You don’t make your own choices, your brain makes them for you” makes as little sense as saying “I didn’t punch you, my fist did it for me”. If physicalism is correct then the brain must be that part of our body which we use to make our own decisions, just as the fist is that part of the body we use to punch people; therefore, our decisions being made in our brains doesn’t imply that we don’t make our decisions.

Of course, that’s only a part of the argument being presented here; if we accept that decisions are made in the brain and that the brain is a part of us, the physicalist incompatibilist can still object that the brain does not behave by its own volition; its behavior is dictated by the laws of nature, thus it is those laws which are really responsible for our decisions, not our brains. But this argument is based on a certain assumption about the metaphysical “nature” of the laws of nature.

To say that the laws of nature dictate that behavior of things only makes sense if we assume that the laws are real things which objectively exist somewhere “out there”, with real causal power and the ability to make everything physical behave a certain way. While I won’t argue against this being a valid interpretation of the laws of nature, it is one which conflicts with the assumption of physicalism. After all, the laws aren’t physical objects–they lack all qualities of physical objects, such as mass, electrical charge or spatial location. If the laws exist, they exist as non-physical things which somehow lord over the physical world–literally super-natural (above nature). Since the laws under this interpretation aren’t physical, this interpretation contradicts the premise of physicalism that the argument is based on.

Again, if we’re to assume physicalism we must be consistent about it; physicalist incompatibilists can’t use an interpretation of the laws of nature under which they’re non-physical entities to argue for physicalist incompatibilism. A more fitting interpretation would be that the laws of physics are human inventions that describe certain regularities that have been observed in nature. Under this interpretation the laws of physics can’t force anything to do anything, therefore they can’t responsible for our decisions.

So, having analyzed and rejected the basic argument for physical determinism being incompatible with free will, does that mean the position can be discarded altogether? Well, no, not yet. There is one argument for incompatibilism that I consider much more convincing, which I’ll be getting around to some two posts after this one. In the meantime, my next post on the topic will be on the idea that having free will requiers that we “could have done otherwise”.

Other posts in this series:
Part 1 — On “Free Will”
Part 3 — Free Will: “Could Have Done Otherwise”
Part 4 — Free Will: Incompatibilist “Freedom”

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