How do you know that two predictable actions composed must equal another predictable action?Because we can only call something 'predictable' if we know how we can predict it. So we already have a working model of the possible interactions involved, and we know what it will do.
You can always speculate that things will somehow be different this time, because every moment in time is unique and induction doesn't provide certainty. Well, there is error in all things, and any conclusion we reach is uncertain - no reason to refuse to conclude. Maybe basic logical truths don't hold, or we incorrectly believe we've described things so our conclusions won't be accurate. That's life.
If you're really not certain how the actions will interact with each other, they're not 'predictable' in regard to the consideration we've giving them.
The conscious mind isn't aware of the total brain mechanism that makes decisions, but it is aware of important pieces of that computation.Actually, it may not be. It may merely be convinced that it is. The consciousness may keep a record of some of the things the mind does, but we know it's an imperfect record, and an awful lot seems to be consciousness making things up in retrospect.
Followup to: Possibility and Could-ness
Arthur Schopenhauer (1788-1860) said:
For this fascinating sentence, I immediately saw two interpretations; and then, after some further thought, two more interpretations.
On the first interpretation, Schopenhauer forbids us to build circular causal models of human psychology. The explanation for someone's current will cannot be their current will - though it can include their past will.
On the second interpretation, the sentence says that alternate choices are not reachable - that we couldn't have taken other options even "if we had wanted to do so".
On the third interpretation, the sentence says that we cannot control our own desires - that we are the prisoners of our own passions, even when we struggle against them.
On the fourth interpretation, the sentence says that we cannot control our own desires, because our desires themselves will determine which desires we want, and so protect themselves.
I count two true interpretations and two false interpretations. How about you?