Sometime in November, I went visiting a Nebraskan couple in Utrecht. They are both very good people and philosophically inclined, he from a background in medical studies, she with a creative and literary bent of mind. They looked exceedingly happy together, and it was very good to be there; of necessity I must summarize this part briefly, for, as Tolkien remarked, it is much easier to tell a story about bad times than about good times (I paraphrase).
At table, we talked about our lives and our studies. I mentioned my desire to investigate, at some point or other, our capacity of making free decisions. This has become problematic in light of neurological discoveries (of which I admittedly know little). It is all very well to say that the human person is capable of self-determination, but our physical infrastructure seems externally determined through and through.
The lady from Nebraska said that she believed in free will, and that her stories involved people making truly momentous ethical decisions that changed their lives. Some universitarians (those gowned cogs in the 21st-century machine) considered her too much a Romantic. I cordially sympathized with her outlook, myself undergoing enthusiasm; then went home and tried to make the best case I could make against free will, so that a more skilful philosopher could blow it to bits and perpetually reroute the depraved neurons responsible for this intellectual atrocity.
Consider yourself invited.
1. Every act of the will has a mental and a material component.
2. The mental and the material components are in proportion to each other.
3. The material component follows the laws of matter.
4. At the molecular level, the motion of matter does not deviate from Newtonian patterns.
5. The material component of the act of the will occurs in the brain at the molecular level. (*)
6. The motion of the material component does not deviate from Newtonian patterns. (from 3, 4 and 5)
7. The mental component is in proportion to a material component that does not deviate from Newtonian patterns. (from 2 and 6)
8. One and the same material component is in proportion to one mental component only. (**)
9. The mental component cannot deviate from a pattern that stands in proportion to the Newtonian pattern governing the material component of the act of the will. (from 7 and 8)
10. A will that cannot deviate from a pattern is not a free will.
11. Hence, there is no free will. (from 9 and 10)
(*) Though the act of the will involves more than a motion of the brain, yet that motion is decisive for human movement.