We seek causes for most changes that we observe. "I wouldn't be surprised to find that brains have built-in tendencies to try to represent all situations in certain special ways: THINGS, DIFFERENCES, CAUSES, CLAUSES." These tendencies are built into our very language, suggesting to Minsky that our brains make us seek to represent dependencies.
NB: The classes of representation noted here (things, differences, causes, clauses) remind me a great deal of some of the basic components of Jackendoff's conceptual structure. Jackendoff makes a great deal of use of the idea that the world offers (through our interaction with it) particular natural kinds; these overlap with Minsky's.