EmeraldBeetle
Thanks for these clarifications. You continue to claim that my portrayal of determinism can be dismissed as a strawman, because I argue that your position cannot account for the reality that you “freely decide”, as you put it. I have been engaging with your position as closely as I can precisely to avoid the impression that I am dismissing it unfairly. I will once again address each of the points you raise to highlight what I see as problematic.
1. GR is indeed the best classical approximation for macro-scale dynamics, and yet it is not a theory of everything. It is partly for this reason that my essay on the efficacy of life argues that it is valuable to expand the scope of explanations to the quantum domain.
2. It’s also clear that we agree that a macro-scale deterministic picture represents conditional dependencies in a static tenseless form. However, what this means is that there is no “free choice” in the local branching of worldlines – all causal dependencies are fixed from the initial conditions onwards, which is precisely what is implied by their “static tenseless” form.
3. Note that I was referring specifically to “downward” causality, which is not permitted by GR. The stress-energy tensor and curvature are mutually determined at every point, but this is a timeless equivalence across the whole manifold. In any case, the analogy you draw between GR and the game of chess is insightful, because it pinpoints the source of your confusion. The rules of chess do not state-determine the sequences of moves; it is assumed that at any point in the game, the current state configuration of the board allows players to freely decide between multiple possible moves. This is where the analogy with GR breaks down: the “rules” of GR (Einstein’s field equations) completely state-determine the sequence of moves.
4. Once again, I agree that science is built on accepting that we have the capacity to freely vary experimental conditions so that we can evaluate causality. I do not rule out dependencies; I only reject the assumption of determinism.
In the deterministic macro-scale picture you seem to be defending, it is simply not possible to claim that you can “freely decide” to act and thereby “alter the physical arrangement of stuff in you local light cone […] because you have local agency.” It would be more accurate to say that the movement of your body was determined by the curvature of spacetime. At best, we end up with a picture of agency like puppets on a string, with the puppeteer being macro-scale physical law. As you yourself write: “nothing in deterministic physics says you could not have acted differently had the relevant conditions been different” – right; and just like when the puppeteer pulls the strings differently, the puppet moves differently. I hope that you can see that it is a stretch of words to say that the puppet “freely decides” how to move because its movement is causally dependent on its external conditions.
In general, the best current macro-scale theories are all deterministic, and this formally means that they do not permit switching from one local state trajectory to another, at least not without global changes such as replacing boundary conditions. Hence, in order to properly ground the very possibility for an agent to switch trajectory in accordance with its own choices, we need to look elsewhere. As a starting point, we must take a closer look at the one scientifically acceptable source of indeterminism in the universe, which is the quantum domain. This is the foundation on which a theory of life, and of agency more generally, must be built.
Thanks again for the exchange. It is helped to sharpen these ideas.
