For example, somebody just pulled a trigger. Contextually, it could be a great thing, or a terrible thing, or in between. But what went on a second before in that person’s brain, a minute before in the environment that triggered the brain, hours before in the person’s hormone levels, years before when this person was a fetus, a millennium ago when the ancestors were inventing the culture that influenced how the mother constructed the person’s brain through her actions within minutes of birth?
Look at a behavior that’s just occurred, and let’s make it an atomistic thing like the example I used a minute ago: you’ve pulled a trigger. Here are the four neurons in your motor cortex that told your muscles to flex. You ask, Why did those four neurons just do that? To show free will, show me that those neurons would have done exactly the same thing regardless of what all the other neurons around them were doing. But that’s not enough. Show me that those four neurons would have done the exact same thing if you weren’t exhausted, or stressed, or euphoric, or blissful, or if your hormone levels had been different, or if the trauma that happened a year ago had never happened, or if you hadn’t found God 30 years ago, or if you had been raised in another culture, or if you had completely different genes. If you could change all of those variables and those four neurons would still have done that exact same thing at that moment, you’ve just proven those four neurons have free will. But you can’t. Everything is embedded in what came before.
Know Thyself 