[abeppu]

I'm still confused. The steam whistle is built intentionally, alongside the locomotive, and together the train serves a clear, externally imposed purpose. The whistle doesn't impact the function on the engine, but a train with a whistle was decided to be a better train, because it does casually interact with the train's environment.

I get the ontological claim that mental states are real but cannot cause effects on physical states. But it seems unsatisfactory to claim that these rich, real but non causal states just happen to arise, without purpose, in only some physical systems, without further explanation.