Human brains have to be deterministic (though indeterminism would not give us free will anyhow)

Are human brains deterministic? That is, are the decisions that our brain makes the product of the prior state of the system (where that includes the brain itself and the sensory input into the brain), or does quantum indeterminacy lead to some level of uncaused randomness in our behaviour? I’ll argue here that our brains must be largely deterministic, prompted by being told that this view is clearly wrong.

First, I’ll presume that quantum mechanics is indeed indeterministic (thus ignoring hidden-variable and Everettian versions). But the fact that the underlying physics is indeterministic does not mean that devices built out of quantum-mechanical stuff must also be indeterministic. One can obtain a deterministic device simply by averaging over a sufficient number of low-level particle events. Indeed, that’s exactly what we do when we design computer chips. We build them to be deterministic because we want them to do what we program them to do. In principle, quantum fluctuations in a computer chip could affect its output behaviour, but in practice a minimum of ~50 electrons are involved in each chip-junction “event”, which is sufficient to average over probabilistic behaviour such that the likelihood of a quantum fluctuation changing the output is too small to be an issue, and thus the chip is effectively deterministic. Again, we build them like that because we want to control their behaviour. The same holds for all human-built technology.

Does quantum indeterminism defeat reductionism?

After writing a piece on the role of metaphysics in science, which was a reply to neuroscientist Kevin Mitchell, he pointed me to several of his articles including one on reductionism and determinism. I found this interesting since I hadn’t really thought about the interplay of the two concepts. Mitchell argues that if the world is intrinsically indeterministic (which I think it is), then that defeats reductionism. We likely agree on much of the science, and how the world is, but nevertheless I largely disagree with his article.

Let’s start by clarifying the concepts. Reductionism asserts that, if we knew everything about the low-level status of a system (that is, everything about the component atoms and molecules and their locations), then we would have enough information to — in principle — completely reproduce the system, such that a reproduction would exhibit the same high-level behaviour as the original system. Thus, suppose we had a Star-Trek-style transporter device that knew only about (but everything about) low-level atoms and molecules and their positions. We could use it to duplicate a leopard, and the duplicated leopard would manifest the same high-level behaviour (“stalking an antelope”) as the original, even though the transporter device knows nothing about high-level concepts such as “stalking” or “antelope”.

Compatibilism for incompatibilists: free will in five steps

Along with cats and cowboy boots a long-running theme of Jerry Coyne’s website has been Jerry’s arguments against any form of “free will”. This usually leads to long comment-thread arguments between the incompatibilists (or “hard determinists”) and the compatibilists amongst Jerry’s readers.

I get the impression that sometimes the incompatibilists don’t properly understand a compatibilist view. They often accuse compatibilists of disliking determinism, of hankering after dualism, hoping that something will turn up that will overturn current science, or of just equivocating. Here I want to explain compatibilism to those determinists who take an incompatibilist stance (“hard determinism”). It is not aimed at libertarian dualists!

First, let’s be clear on the two stances. Compatibilism asks whether, given a deterministic universe, one can arrive at sensible and coherent meanings of terms such as “choice”, “freedom” and indeed “free will”. The compatibilist says yes; the incompatibilist says no, regarding such terms as too tainted by the dualistic idea that humans have a non-material “soul” that can make “choices” that are independent of the physical state of the brain and which thus violate the laws of physics.

Second, we should also be clear that the compatibilist is not disagreeing with the incompatibilist over any aspect of science. The compatibilist is only disagreeing over the meaning of concepts such as “choice” and “freedom”. Thus:

Why Jerry Coyne is barking up the wrong tree on moral responsibility and free will

Professor Coyne’s website Why Evolution is True is one of my favourites and generally his views align well with mine. I part company with him, though, in his long-running campaign to get rid of notions of “moral responsibility” and “free will”.

“Moral responsibility”, as often defined and as Coyne uses it, is the notion that morality is an absolute, such that a “morally bad” act should be met with punishment regardless of what any human might think and regardless of any consequences for humans. This is often coupled with the notion that humans have dualistic “free will” and that “moral” choices are those made by this non-material, dualist “will” (in opposition to the idea that human decisions are determined by the physical state of the brain).

Coyne (writing in America) sees these ideas as harmful, first in bolstering religion, and second in leading to a justice system that is based on retribution; he considers that justice should instead be based on deterrence and crime mitigation, coupled with sympathy for criminals through recognition that they are largely the products of their environment.

I agree with Coyne’s rejection of deontological morality and with his rejection of dualistic free will, and I also agree with Coyne’s ideas about the justice system. Yet it seems to me that Europe has already progressed down the lines Coyne wishes to see, and it has done so, not by removing motions of morality and free will from society, but by becoming less religious.

Lacking “free will” does not negate moral responsibility

A long-running feature of Jerry Coyne’s popular website has been his discussion of “free will”. Jerry sensibly rejects all notions of mind/body dualism or any notions of a supernatural “soul” which can over-ride the laws of physics.

However, Jerry is at odds with many of his readers in rejecting any notion of “free will” that is compatible with a deterministic universe. Such “compatibilist” stances have been advocated, for example, by Dan Dennett in his 2003 book “Freedom Evolves”, and recently by Sean Carroll.

In essence that dispute is simply about semantics, with both sides agreeing on the physical reality. To illustrate this, consider a laptop computer which looks at the type of a computer file and “chooses” the most appropriate program to open it with.

One could justly declare that, in such uses, the word “chooses” is purely metaphorical, since the computer’s actions are entirely determined by its programming. However, for everyone except those arguing for a supernatural soul which over-rides physics, all other “choices”, by humans or other intelligent animals, must be equally metaphorical, since they are also determined by the prior state of the system.

Thus we have two possibilities, either drop the words “choice” and “decision” from the English language, along with a whole slew of similar words and phrases (“control”, “attempt”, “option”, “plan”, “threaten”, “test”, “compel”, “consider”, “coerce” for starters), or accept that “metaphorical” choices are all there is in this universe, and thus that the word “choice” is quite properly used about deterministic machines when they make a selection from a range of options.

Dennett’s argument is that humans have evolved a sufficiently complex range of responses to any situation that it is sensible to regard them as autonomous agents making “choices” of their own “will”. The word “will” here indicates that it is their own internal properties that are making the “choice”, even though that choice is entirely determined by those internal properties combined with the laws of physics. The word “freedom” in Dennett’s title “Freedom Evolves” indicates that mammals have evolved the flexibility to respond in ways that suit themselves and their own purpose, going beyond the very narrow responses of a simpler or more primitive entity.