Does linguistic explanation presuppose linguistic description?

I argue that the following two assumptions are incorrect: (i) The properties of the innate Universal Grammar can be discovered by comparing language systems, and (ii) functional explanation of language structure presupposes a “correct”, i.e. cognitively realistic, description. Thus, there are two ways in which linguistic explanation does not presuppose linguistic description.

The generative program of building cross-linguistic generalizations into the hypothesized Universal Grammar cannot succeed because the actually observed generalizations are typically one-way implications or implicational scales, and because they typically have exceptions. The cross-linguistic generalizations are much more plausibly due to functional factors.

I distinguish sharply between “phenomenological description” (which makes no claims about mental reality) and “cognitively realistic description”, and I show that for functional explanation, phenomenological description is sufficient.