First order thinking works really well when dealing with spherical cows and ignoring air resistance. Once nuance and the fractal complexity of the real world come into play factors come into play, empirical phenomenon and experience become much more important. How much weight you gove to first principles depends on how theoretical or practical your domain is, e.g. science vs engineering.
I think I'll stop commenting in this thread as it seems like no two people in this thread are using compatible meanings of "first principles" thinking. Forget about equivalent meanings of it.
"First order" thinking from my knowledge is an entirely different concept.
