ill try to clarify his argument. its very simple conceptually but language doesnt serve well in this sorts of discussions... if you feel like reading for 10min, follow along
imagine a simple unicellular organism with certain proteins on its membranes. a predator comes by that wants to eat it, but there are a bunch of a certain molecule coming off the predator cell (we'll call it molecule A) and the prey cell developed a mechanism to detect these as a sign of a predator
when molecule A hits one of these proteins, the protein changes in shape, which in turn changes the shape of a nearby protein (its shape now makes it take an ATP and pass it to a collection of proteins)
these proteins function as a rotary motor, they twirl and flip a flagella protruding from that part of the membrane
the result is the unicellular organism zips away from the predator
this is life. it's all mechanical. it's an example of reducing complex events that you see in real life (e.g. human behavior) to the molecular level (and the moleuclar level is predictable). everything in biology is reducable to this level
now, why do 'choose' to grab something? because the molecules in your brain are doing their own thing. you have the illusion that you chose to grab it because your molecules are acting as a computer, and your brain/computer sees a number of possible actions it can do, and it chooses
what determinism says, is that all this thinking, planning, and choosing, is reducible to this physical level, and therefore it's all predictable given sufficient data because physical matter follows physical laws. tell me how htis doesnt make sense?
