Choice functions: rationality re-examined.

On analyzing the problem that arises whenever the set of maximal elements is large, and a selection is then required (see Peris and Subiza, 1998), we realize that logical ways of selecting among maximals violate the classical notion and axioms of rationality. We arrive at the same conclusion if we analyze solutions to the problem of choosing from a tournament (where maximal elements do not necessarily exist). So, in our opinion the notion of rationality must be discussed, not only in the traditional sense of external conditions (Sen, 1993) but in terms of the internal information provided by the binary relation