 As indicated, this unity must be a priori since it cannot be given through any set of experiences. Nor can we know in advance how far science will succeed, or that nature is wholly law-like. So the principle of seeking unity forms (what Kant calls) a “maxim” or regulative principle of reason (A666/B694; see Mudd 2016 for recent discussion of this principle and its practical nature). By contrast, the claim that such unity does exist would represent a “constitutive principle,” the sort of “cosmological” knowledge claim that we cannot justify.