Nowadays there is a reunion of social and human sciences, a so-called transdisciplinarity can be observed. An example of this process is the research on rationality, which is the object of psychology, sociology and economics as well. These sciences use the findings of the others. According to mainstream economics the rational actor is fully informed, capable of calculating and preference ordering. His preference order is transitive, reflexive and total, his decisions are consistent. The theory of bounded rationality offers solutions to the problems arising from the lack or plethora of information, from the deficiency of calculative capability and the time required for a decision. It is debated whether the acts governed by emotions or norms are rational ones or not. New theories in the field of decisions under uncertainty try to give an explanation to the harms to the axioms of preference ordering.