 it seems perfectly natural to stick to this condition even if the range of π is extended from {0, 1} to [0, 1]. Likewise, the question of whether mereological indeterminacy implies vague composition or vague existence is generally answered in the affirmative (though not always; see e.g. Donnelly 2009 and Barnes and Williams 2009). Van Inwagen (1990: 228) takes this to be a rather obvious consequence of the approach, but N. Smith (2005: 399ff) goes further and provides a detailed analysis of how one can calculate the degree to which a given non-empty set of things has a sum, i.e., the degree of existence of the sum. (Roughly, the idea is to begin with the sum as it would exist if every element of the set were a definite part of it, and then calculate the actual degree of existence of the sum as a function of the degree to which each element of the set is actually part of it). 