 A fourth and final version of the third strategy, developed independently (and somewhat differently) by Balaguer (1995, 1998a) and Linsky &amp; Zalta (1995), is based on the adoption of a particular version of platonism called plenitudinous platonism (Balaguer also calls it full-blooded platonism, or FBP, and Linsky and Zalta call it principled platonism). Balaguer defines plenitudinous platonism (somewhat roughly) as the view that there exist mathematical objects of all possible kinds, or the view that all the mathematical objects that possibly could exist actually do exist. But, in general, Balaguer would define a different plenitude principle for every different kind of abstract object. Linsky &amp; Zalta develop plenitudinous platonism by proposing a distinctive plenitude principle for each of three basic domains of abstracta: abstract individuals, relations (properties and propositions), and contingently nonconcrete individuals (1995, 554). For example, on their view, the plenitude principle for abstract individuals asserts (again, somewhat roughly) that every possible description of an object characterizes an abstract object that encodes — and, thus, in an important sense, has — the properties expressed in the description. 