Free Will (Sam Harris book)

The thesis of Sam Harris’s book Free Will is that we don’t have it.

First: what is free will? Let’s say it’s some inner spark of agency that cannot be explained exogenously, i.e. isn’t just biology, physics, culture, law, random flukes, etc.

The argument starts with the observation that at minimum, we are much more constrained by these exogenous factors than we normally assume. Obviously we’re limited by the laws of physics and biology, but beyond that, surely our wills are free to do whatever? Not so fast. I might think to myself, “right now I could take any action that isn’t physically impossible.” But could I really? Could I break all the windows in my apartment? Could I throw my laptop at a passing truck? Could I moonwalk everywhere for the next week? Naively, I might say I simply won’t do those things because I anticipate negative consequences. But there’s also a sense in which I literally could not do those things. They are too incongruous with my needs and values. So, it shouldn’t be much of a stretch to accept the premise that all those exogenous factors at least limit us to some small set of likely actions. E.g. maybe I’ll read a book, or go for a walk, or scroll through Twitter, or call my mom.

Already we might ask ourselves: how free is this will, exactly, if it’s so constrained? But most people aren’t that extreme. As long as there’s some room for that inner spark of agency to guide us around in our cages, our wills are free enough. (Dennett basically argues this.) So, that apparent freedom to choose whether I’ll read a book or scroll through Twitter—is there an exogenous explanation for that too? Well, yeah, there are probably several. Maybe I woke up to a few notifications this morning that sucked me into Twitter. Maybe the book I’m currently reading happens to be a bit of a slog. Or maybe it’s a page-turner! Maybe my phone battery runs out and I pick up the book to entertain myself while my phone charges. Etc.

Now, what if we strip away all the environmental prompts—is there still free will underneath? Well, if I’m deciding between two options, I’m evaluating the options according to a utility function—something that maps the attributes of each option to the things I care about. Say I’m choosing which car to buy. I care about its price, its energy efficiency, its size, its appearance, etc. The question is: what determined how much I care about each of those variables? Where does my utility function come from? Alas, it came from exogenous factors! I didn’t choose to care about paying a fair price; I didn’t choose to care about conserving energy; I didn’t choose to care how often people compliment my sweet ride. All those values had external causes. Even if I arrived at some of those values via an internal reasoning process, I didn’t choose the meta-values by which I evaluated the conclusions of that process. I’m never the prime mover.

I think that lays out most of the theoretical argument, as I understand it. Harris also gives a bunch of examples that drive the intuition further. One that stood out to me is the story of Charles Whitman, the “Texas Sniper”, who in 1966 killed his mother and wife, then climbed a tower at the University of Texas and shot at random people for an hour and a half, killing a total of 17 people. Before doing all this he wrote a suicide note asking for his brain to be examined in an autopsy. Here’s part of the note:

I do not quite understand what it is that compels me to type this letter. Perhaps it is to leave some vague reason for the actions I have recently performed. I do not really understand myself these days. I am supposed to be an average reasonable and intelligent young man. However, lately (I cannot recall when it started) I have been a victim of many unusual and irrational thoughts. These thoughts constantly recur, and it requires a tremendous mental effort to concentrate on useful and progressive tasks.

It turned out that he had a pretty huge brain tumor, pressing against his amygdala. Harris suggested here that the tumor was an obviously indispensable part of the explanation for Whitman’s behavior, although not everyone agrees. Anyway, the point is that some people do have neuropathologies that evidently affect their behavior. But where’s the line between neurology and neuropathology? Arguably, for all of us behavior is just “brain tumors all the way down.”

I won’t be surprised if you aren’t convinced by the argument I laid out here. For whatever reason I find it hard to talk about clearly. But if you’re interested in the subject, I recommend the book! It’s short, engaging, and thought-provoking. You might also enjoy hearing Very Bad Wizards discuss it with Sam in this podcast episode.

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