 Unique determination and Requisite determination may also admit of exceptions. Wilson (2013) argues that even for paradigmatic determinables such as color, Unique determination is not generally correct, since the case of an iridescent feather is reasonably interpreted as one in which the feather is (a) colored, (b) red from one perspective, and (c) blue from another perspective, such that no one determinate shade is non-arbitrarily identified as “the” unique determinate determining the determinable color had by the feather (rather, she suggests, the determinates are had, at best, in relativized  fashion).[8]  More generally, she argues that there can be failures of Unique determination due either to there being too many candidate determinates (as in the feather case) or to there being too few or none, contra Requisite determination (as might be the case for certain quantum phenomena; see below). Fales observes that Requisite determination 