Spectacular phenomena and and limits to rationality in genetic and cultural evolution

In this paper we question one of the paradigms in the behavioural sciences in the last century. We call it the "rationality" paradigm, according to which animal and human behaviour can be understood from the assumption that it is "rational" with respect to reaching a given goal. For instance, animals are assumed to take the best course of action for maximising their reproductive success, and actors in an economic game are assumed to maximise their profit. This kind of reasoning is strongest is evolutionary biology and game theory, but the broader notion that behaviour has a "meaning" is widespread in the social sciences as well. We argue that both empirical and theoretical studies of the evolution of communication question the rationality paradigm, and strongly suggest that whenever organisms interact in conflict situations behaviour strategies will evolve that cannot be fully understood as rational.