  Traditional cognitive science rests on a foundation of classical logic and
probability theory. This foundation has been seriously challenged by several
findings in experimental psychology on human decision making. Meanwhile, the
formalism of quantum theory has provided an efficient resource for modeling
these classically problematical situations. In this paper, we start from our
successful quantum-theoretic approach to the modeling of concept combinations
to formulate a unifying explanatory hypothesis. In it, human reasoning is the
superposition of two processes -- a conceptual reasoning, whose nature is
emergence of new conceptuality, and a logical reasoning, founded on an
algebraic calculus of the logical type. In most cognitive processes however,
the former reasoning prevails over the latter. In this perspective, the
observed deviations from classical logical reasoning should not be interpreted
as biases but, rather, as natural expressions of emergence in its deepest form.
