The inference from determinism to predictability, though intuitively plausible, needs to be qualified in an important respect. We need to distinguish between two different kinds of predictability. On the one hand, determinism implies external predictability , that is, the possibility for an external observer, not part of the universe, to predict, in principle, all future states of the universe. Yet, on the other hand, embedded predictability as the possibility for an embedded subsystem in the universe to make such predictions, does (...) not obtain in a deterministic universe. By revitalizing an older result—the paradox of predictability —we demonstrate that, even in a deterministic universe, there are fundamental, non-epistemic limitations on the ability of one subsystem embedded in the universe to predict the future behaviour of other subsystems embedded in the same universe. As an explanation, we put forward the hypothesis that these limitations arise because the predictions themselves are physical events which are part of the law-like causal chain of events in the deterministic universe. While the limitations on embedded predictability cannot in any direct way show evidence of free human agency, we conjecture that, even in a deterministic universe, human agents have a take-it-or-leave-it control over revealed predictions of their future behaviour. (shrink)

If the laws of nature are deterministic, then it seems possible that a Laplacean intelligence that knows the initial conditions and the laws would be able to accurately predict everything that will ever happen. However, it would be easy to construct a counterpredictive device that falsifies any revealed prediction about its future behavior. What would then occur if a Laplacean intelligence encountered a counterpredictive device? This is the paradox of predictability. A number of philosophers have proposed solutions to it, though (...) part of my aim here is to argue that the paradox is more pernicious than has thus far been appreciated, and therefore that extant solutions are inadequate. My broader aim is to argue that the paradox motivates Humeanism about laws of nature. (shrink)