For Universal Grammar (UG), the identification of substantial universals seems unprincipled, because it is indeterminable, with solely bottom-up assumptions, whether a category advanced in UG is entailed by the notion of innateness, or on that basis, what sufficiently evidences its presence. Unable to constrain the theorization of UG, innateness only seems to be inexplicable, that is, it must be questioned how UG is framed within an innate blueprint. I contend that bottom-up assumptions hardly create an innate universal grammar. A theory resulting from bottom-up assumptions is contingent whereas UG must be a promise that the hypothetical Language Faculty (LF) is epistemologically unique (necessary truth). From bottom up, the identity of a linguistic item always points to multiple possibilities and is ad hoc, as no one has real access to the way that a linguistic item naturally exists in LF. Therefore, unless the principle(s) of how categories are recognised and organised in the LF can be genuinely set out for UG, so that its categorisation inputs all linguistic items methodically and outputs their identities uniquely, the putative substantial inventory of UG is unlikely to be complete and systematic: categories in it are merely opportunistically thrown up on random grounds.
Xie, W. (2023). The methodological incompatibility between an innate grammar and a bottom-up approach. SN Social Sciences, 3(31), https://doi.org/10.1007/s43545-023-00619-5