 Properties are typically invoked to explain phenomena of philosophical interest. The most traditional task for which properties have been appealed to is to provide a solution to the so-called “one over many problem” via a corresponding “one over many argument”. This traces back at least to Socrates and Plato (e.g., Phaedo, 100 c-d) and keeps being rehearsed (Russell 1912: ch. 9; Butchvarov 1966; Armstrong 1978a: ch. 7; Loux 1998: ch.1). The problem is that certain things are many, they are numerically different, and yet they are somehow one: they appear to be similar, in a way that suggests a uniform classification, their being grouped together into a single class. For example, some objects have the same shape, certain others have the same color, and still others the same weight. Hence, the argument goes, something is needed to explain this phenomenon and properties fill the bill: the objects in the first group, say, all have the property spherical, those in the second red, and those in the third weighing 200 grams.