Wim van der Steen charts conceptual foundations of evolutionary biology and, on the basis of this, he evaluates applications of evolutionary theory outside biology. Philosophical analysis shows that key notions of the theory such as fitness, adaptation, selection, and optimality are empty place-holder concepts that call for context-dependent specifications of meaning. For example, as he points out, the notion of optimality is empty without a specification of constraints. Hence, the controversial thesis that animals perform optimal behaviors as a result of natural selection is meaningless rather than true or false. Analysis shows that many other controversies in evolutionary biology are spurious. Thus, the thesis of genic selectionism, which puts genes at center stage in evolutionary theory, is best reconstructed as an arbitrary conceptualization without substance. Disagreements over the thesis are futile. They reflect preferences for different conceptualizations which are ultimately equivalent.

As concepts are properly specified, van der Steen asserts evolutionary theory turns out to be a body of interesting natural history at a low level of generality. General laws of evolution do not exist. Hence, evolutionary approaches do not allow sweeping claims about human nature. Unfortunately, in disciplines outside biology such claims are often defended with evolutionary approaches. Evolutionary theory also cannot serve as a foundation for normative views in ethics or epistemology. This is an important and controversial work for scholars and advanced researchers in biology and the philosophy of biology.