 This last pattern of argument can be extended. Indeed, given that every natural system undergoing selection also undergoes drift, evolutionary theory is arguably applicable also to systems that undergo drift even in the absence of selection (in the focused sense). Gradually reduce the importance of focused selection in the above system of equations, that is, gradually reduce the differences between \(w_{D}\), \(w_{H}\), and \(w_{R}\). Is the point at which the values equalize so momentous that it marks the point at which systems governed by the equations cease to fall within the purview of one theory and instead fall within the purview of another? Does Kimura’s neutral theory of genetic polymorphism belong in a different theory than does Ohta’s (1973) competing nearly neutral theory? Brandon (2006) argues that the principle of drift is biology’s first law, writing that neutral evolution is to evolutionary theory what inertia is to Newtonian mechanics: both being the natural or default states of the systems to which they apply. If Brandon is right, then conditions for the application of evolutionary theory must not even include conditions for selection in the focused sense, much less conditions for evolutionary change.