In this chapter, rationality of a theory is understood in a specific sense, not Platonian but close to the understanding by Popper (1934, 1972) and Quine (1964): a theory is rational if it can be deduced from abstract principles and reasonable assumptions, but is also empirically sound, according to Quine it touches the reality at its edges and according to Popper it can be falsified experimentally or, at least, allows to draw conclusions that can be checked in practice. This chapter shows that intuitive abilities of humans can be explained in terms of evolution, in particular—civilization evolution and the emergence of verbal communication.