Reading Daniel Kahneman's new book,Thinking, Fast and Slow, still in the early chapters. He discusses "priming", the idea that by association of ideas exposure to one thing will increase the relevance of others. For example, if you're given "W--H" and "S--P" to complete after being exposed to words like "dirt" you'll likely say "wash" "soap", while if you were exposed to "hunger" it would be "soup". This is imperceptible to the person, part of what he calls System 1, though well-established by experiments.
This would explain the saying: "to the boy with a hammer, everything looks like a nail". The boy is primed by the hammer to see things as items to be hit.
It also explains why economists and humanists think so differently: their priming is different. Economists talk money much of the time; humanists say, with Mr. Dodgson: "The time has come, the Walrus said,To talk of many things:Of shoes and ships and sealing-wax Of cabbages and kings And why the sea is boiling hot And whether pigs have wings."