Determinism

2019-10-11

I have a degree in physics. To get that degree, I had to jump through a lot of
hoops, many of them made from dry-erase markers, exams, and the tears of
overworked graduate students. In the process of learning how to jump through
those hoops, several principles were beaten into me and my classmates.

Among these was the principle that everything that happens in the universe is
the result of consistent, explainable rules that we like to call Laws. This is
perhaps the core tenet of physics: the Laws are the same no matter where or
when you go in the universe. We don't know what all the Laws are yet, but in
attempting to figure them out we proceed with the expectation that the complete
set will have some character, some nature that's consistent. If it turns out
that the Laws change based on your position in spacetime, well, that would
probably ruin some people's whole day. Others would be ecstatic.

Anyway, the implication of this tenet is that nothing can exist outside the
realm of the Laws. Everything, we assume, must obey them. Otherwise, either our
Laws would be incomplete, or we would be forced to conclude that some things
are extraphysical (read: magic). That's just no fun, so we assume that it's not
true. So far, there hasn't been any good evidence to disprove that assumption,
so after a few centuries of building we've become pretty confident in it.

Many systems in the universe are complex. That is, they're so large and have so
many pieces that we---collectively or individually---can't take them up in our
minds very well. They don't fit, because our minds are more or less the
products of evolution, and our ancestors didn't have a lot of quarks to
interact with in the savanna (at least, as far as they knew). For this reason,
we often need to abstract systems into smaller pieces so we can fit them into
our thinking mouths and chew on them. The problem with these abstractions is
that they necessarily discard some of the information in their creation, sort
of like how you have to discard some wood shavings in order to whittle a duck,
or whatever. Discarding information is critical to their function, after all,
but it's still an unfortunate consequence. If we keep doing this and abstract
away too much, then what we're left with is an over-simplified model of the
real thing.

Abstractions make it easy to forget our fundamental assumption (at least, in
physics) that the universe operates according to physical Laws. That's
important, because assumptions like that have critical implications for
questions that seem like they couldn't be further from physics, such as the
question of free will.

Can you do what you want? You may think so, but you're wrong. You---your body,
anyway, which is what *you* are---exists in the universe. You're made of
matter, and as far as anybody can tell empirically, your body obeys the same
physical Laws as anything else in the universe. Inside your body is a little
chemical computer that does some fantastic work in real time to take inputs
from the rest of your body and send outputs back to it. That's how you're
reading these words, and it's how I'm able to send them to you, more or less.

Suppose you turn off the device you're reading this on, perhaps because you
think I'm a pretentious prick for trying to leverage a moderate level of
science education into a definitive answer to the free will question. Did you
*decide* to do that? Well, let's work backward. Lastly, your body moved in such
a way that the device turned off. That required that some muscles move around,
converting stored chemical energy into motion and some waste heat. Before that,
your brain sent signals to your muscles to expend that energy precisely in that
way.  Before that, your brain took in inputs from your surroundings via various
sensors. Before that, you were reading the last paragraph.

Nowhere in that process is anything like a decision or a thought. We have names
for those things because it *feels* to us like they're happening---like our
minds are places we can go to---but the reality is quite different. Really, we
are wonderful machines that operate according to Laws, no different than stars
or starfish. We don't have free will, *because nothing does*. We just do
whatever the matter in our bodies does.

Consider this: almost nobody would argue that an atom can think. Cells don't
make the cut either, and neither do muscles, bones, or any other organs besides
the brain. And yet, the brain is made up of the same matter as everything else.
The emergent properties of the complex system that is the human brain aren't
unexplainable magic. They're the impressive output of a machine whittled over
eons to do what it does.

You may think this is a frightening conclusion. Perhaps you think that being
predictable, even in principle, lessens your existence. I don't think so. By
fantastic chance, we all have the sensation of making decisions and thinking,
even though we're not. That's a wonderful thing, and we should be happy to have
received such a beautiful gift. Still, remember that we are physical beings,
and unless we allow extraphysical magic, there can be nothing more to our
existence than the natural course of the complex play that is the universe and
its Laws.