The best kind of thinking, which we shall call rational thinking, is whatever kind of
thinking best helps people achieve their goals. If it should turn out that following
the rules of formal logic leads to eternal happiness, then it is “rational thinking” to
follow the laws of logic (assuming that we all want eternal happiness). If it should
turn out, on the other hand, that carefully violating the laws of logic at every turn
leads to eternal happiness, then it is these violations that we shall call “rational.”
When I argue that certain kinds of thinking are “most rational,” I mean that these
help people achieve their goals. Such arguments could be wrong. If so, some other
sort of thinking is most rational.
From Jonathan Baron’s Thinking and deciding: