The proposal to add the behavioral momentum metaphor to Skinnerian psychology and the use of other borrowed physical explanatory concepts such as velocity and inertial mass has only superficial value. The basic problem is that, in contrast to Newtonian physics, the “laws” do not apply to a significant proportion of the phenomena to be explained, and these evidential discrepancies are ignored, rather than being used to modify the scientific explanations and improve technological applications that are based on those explanations.