Determined: A Science of Life without Free Will

Developing post-traumatic stress disorder after trauma transforms the amygdala. Synapse number increases along with the extent of the circuitry by which the amygdala influences the rest of the brain. The overall size of the amygdala increases, and it becomes more excitable, with a lower threshold for triggering fear, anxiety, and aggression.[24]

If that’s the case for some baboon, just imagine humans. We have to learn our culture’s rationalizations and hypocrisies—thou shalt not kill, unless it’s one of them, in which case here’s a medal. Don’t lie, except if there’s a huge payoff, or it’s a profoundly good act (“Nope, no refugees hiding in my attic, no siree”). Laws to be followed strictl

determinism and predictability are very different things. Even if chaoticism is unpredictable, it is still deterministic.

Another study showed that if you feel happy, you perceive that conscious sense of choice sooner than if you’re unhappy, showing how our conscious sense of choosing can be fickle and subjective.[7]

Step #1. Start with a tube of diameter Z (a tube because geometrically, a blood vessel branch, a dendritic branch, and a tree branch can all be thought of that way). Step #2. Extend that tube until it is, to pull a number out of a hat, four times longer than its diameter (i.e., 4Z). Step #3. At that point, the tube bifurcates, splits in two. Repeat

But here’s why these Libetian debates, as well as a criminal justice system that cares only about whether someone’s actions are intentional, are irrelevant to thinking about free will. As first aired at the beginning of this chapter, that is because neither asks a question central to every page of this book: Where did that intent come from in the f

How’s this for rapidly altering frontal function—take an average heterosexual male and expose him to a particular stimulus, and his PFC becomes more likely to decide that jaywalking is a good idea. What’s the stimulus? The proximity of an attractive woman. I know, pathetic.[*23]

Thus, three different techniques, monitoring the activity of hundreds of millions of neurons down to single neurons, all show that at the moment when we believe that we are consciously and freely choosing to do something, the neurobiological die has already been cast. That sense of conscious intent is an irrelevant afterthought.

effects in your brain? Time of day matters, as T levels are nearly twice as high during the daily circadian peak as during the trough. Whether you’re sick, are injured, just had a fight, or just had sex all influence T secretion. It also depends on how high your average T levels are; they can vary fivefold among healthy individuals of the same sex,