“Philosophy of science,” or, “how do we know something to be true, and what is the difference between knowing something and believing something to be true?”

I took such a philosophy course in college and it was quite informative as a way to reason about problems. It helped me with my debugging, to move from “x is the problem” to “I believe x is the problem, and here is why I believe this causal relationship exists.”

I think this is what most of us call “critical reasoning” skills, or “how to think.” But this particular line of causality, and analyzing the strongest statement one could make based on a set of premises, is a skill that has served me well as an engineer.