  Meiosis is an unpromising candidate to illustrate the idea that what appears uniform at the level of classical genetics turns out to be heterogeneous at the molecular level. But this idea is illustrated by other genetic phenomena. Consider the phenomenon of genetic dominance. In classical genetics, all examples of complete dominance are treated alike for the purposes of explaining transmission phenomena. But contemporary genetics reveals that there are several very different mechanisms underlying different instances of dominance. According to Kitcher's unificationist theory of scientific explanation, the classical account of dominance provides an objectively better basis for explaining transmission phenomena because it provides a more unified organization of the phenomena. But this would imply that the shallow explanations of classical genetics are objectively preferable to the deeper explanations provided by the molecular theory (Waters 1990). 