A
particular choice presented itself to me. Which alternative to take was not immediately obvious, and so I pondered the pros and cons of each. After an amount of time in this state, I chose one alternative over the other and acted accordingly.
What would have had to be different about the world for me to have chosen differently? In asking this question, I think we draw a little closer to understanding causality.
Materialists might say something along the lines of "if the arrangement of local atoms were different, you would have chosen differently. Your actions are the result of simple physical processes." Let's investigate this further.
It would seem that my decision-making can sustain a great deal of change to the immediate physical environment. That is, there is a lot of physical "data" around me when I make a choice that is simply irrelevant to my making that choice. If you change the color of my sheets, or the arrangement of leaves on the ground, or the temperature of the air (which, to be clear, would be relatively massive changes in raw molecular terms), my decision-making process would be unmoved. So -- what differentiates the physical changes that make a difference to my decision-making from those that don't?
Let's make the example concrete. I was on my way to church, when Elena realized that she forgot her camera, which we were planning on using later on in the day. I had the choice to either continue on to church, and not be late, or turn around and get the camera. In a couple of seconds, I elected to turn the car around. What could have made me choose differently?
1) If we had been further along the way to church, turning around would not have been worth it. 2) If the event we needed the camera for were not in fact going to happen. 3) If the camera were out of battery or memory. 4) If I had been specifically requested to arrive at church on time, instead of a few minutes late.
Obviously these examples could be multiplied. The point is that, yes, these changes are technically physicaly changes in the world that would have affected what decision I made. However, they are not "just any" changes. My mind inoculates itself from a fantastic amount of irrelevancies when it is deciding, and it is precisely this "screening" that is the point. My mind is not sensitive to "the environment" or my "genetics", considered broadly; it is sensitive to relevant reasons of the matter it is considering. It apprehends these reasons using the laws of physics, and physical interactions, and the environment and my genetics, for that matter. But the mind, like all forms, has a type of independence that lets it "stand apart" from the random motion of atoms, and be a particular "thing". It makes no sense to say I was "fated" to turn my car around by my genetics -- my genetics are perfectly compatible with a situation in which I did not turn the car around. Nor does it make sense to say I was forced by the environment. My mind seized on certain facets of the situation, weighed them, and chose.
This explanation is still not perfect, but I feel I'm getting somewhere.