 Of course, even if one has a fine-grained view that makes partial definability discriminating enough to be interesting, one may have other reasons for rejecting generalizations like (1–8). Lewis  (1970a;  1986b, 56–9), Creswell  (1985),  and Soames  (2002,  ch. 11) propose theories on which there are both “unstructured” and “structured” properties and propositions, with the former conforming to intensionalism, and the latter being in some sense “constructed” (e.g. set-theoretically) out of the former. The notion of “construction”, or its transitive closure, can provide an non-trivial interpretation of partial definability in these theories. But a hallmark of this kind of theory is that every structured property is necessarily coextensive with an unstructured one. Given this, generalisation 6 would imply that every property is necessarily coextensive with a perfectly natural property, a claim that is in obvious tension with the proposals we have considered linking naturalness to similarity, duplication, qualitativeness, modality, lawhood, and mental and linguistic content.