  Understanding the mechanisms underlying the formation of cultural traits,
such as preferences, opinions and beliefs is an open challenge. Trait formation
is intimately connected to cultural dynamics, which has been the focus of a
variety of quantitative models. Recently, some studies have emphasized the
importance of connecting those models to snapshots of cultural dynamics that
are empirically accessible. By analyzing data obtained from different sources,
it has been suggested that culture has properties that are universally present,
and that empirical cultural states differ systematically from randomized
counterparts. Hence, a question about the mechanism responsible for the
observed patterns naturally arises. This study proposes a stochastic structural
model for generating cultural states that retain those robust, empirical
properties. One ingredient of the model, already used in previous work, assumes
that every individual's set of traits is partly dictated by one of several,
universal "rationalities", informally postulated by several social science
theories. The second, new ingredient taken from the same theories assumes that,
apart from a dominant rationality, each individual also has a certain exposure
to the other rationalities. It is shown that both ingredients are required for
reproducing the empirical regularities. This key result suggests that the
effects of cultural dynamics in the real world can be described as an interplay
of multiple, mixing rationalities, and thus provides indirect evidence for the
class of social science theories postulating such mixing. The model should be
seen as a static, effective description of culture, while a dynamical, more
fundamental description is left for future research.
