 Setting aside doubts about the intelligibility of  Definability,  it would seem to be at least as strong as  TSB.[65]  At least in the paradigm cases where a proposition is fully definable out of some properties and objects, the complete truth about which objects there are and which ones instantiate each of those properties will either necessitate that proposition or necessitate its negation. By contrast, the inference from  TSB  to  Definability  is quite controversial. There are arguments which purport to show that whenever a property supervenes on some properties, it is definable in terms of them (Jackson  1998;  Stalnaker  1996);  but these arguments rely on an intensionalist theory of properties, and raise difficult issues even in that setting (Leuenberger  2018).  