And we have all sorts of social science these days implying the explanations when people do try to explain themselves they’re justifying decisions that came out of black box rather than actual describing how the decision happened
What do you (or they) think “our choice” is if not the result of these processes? It’s not like “you” are just the part of your brain that is consciously aware of making decisions.
Asking people to explain themselves often triggers various sorts of youth punishment memory, resulting in them being both uncomfortable probing their own reasoning, and then they produce what is essentially a comforting deception for their reasoning simple for the sake of ending the agony of self probing. Asking people their internal states requires their internal guard and internal (potentially filled with self deception) voice what they are up to is very similar to asking children why they are misbehaving, and all manners of mental protections activate.
You can justify post facto the move you made. Can you write down the logical process (probably a combination of strategy, move generation, analysis and selection) that would replicate the moves you picked from the beginning of the game? I don’t even need the brain chemistry (the implementation), but I don’t think even writing down the logic that generates those moves (in contrast with a logic to justify each move after it was generated) is something humans can do in most cases.
You are not explaining your internal processes (neurobiology, brain chemistry, neuron firing patterns etc.) that caused you to arrive at given moves. You will only provide proofs that your moves are good.