Misunderstanding of the idea of evolution (natural selection) was assumed to occur because students were basing their explanations on the following mistaken assumptions: (1) variations in a population have little importance in its change process; (2) when nature changes, it is not at random. From these assumptions, hypotheses were developed and tested by analyzing the responses of 322 university sophomores (education majors) on an evolution problem “How could the bat have evolved wings?”. A classification system that was developed required judgments on whether a population or typological focus was used, whether the change process was open or closed to environmental information and how the selection process functioned. The contention that misunderstanding is logical was supported by acceptance of the following hypotheses: (1) students adopting a population focus also used a closed-change process; (2) students seeing change as more directed used less functional selection processes, with one exception; (3) students using acquired traits did not use a functional idea of selection.