Existential Relativity

Artifacts and natural objects are normally composed of stuff or of parts in certain ways.Those that endure are normally composed of stuff or of parts at each instant of their enduring.Moreover, the stuff or parts composing such an object right up to t must be related in certain restricted ways to the stuff or parts that compose it right after t, for any time t within its history.Thus a snowball exists at a time t and location l only if there is a round quantity of snow at l and t sufficiently separate from other snow, and so forth; and it endures through an interval I only if, for every division of I into a sequence of subintervals I 1, I 2 , . . ., there is a corresponding sequence of quantities of snow Q 1 , Q 2 , . . ., related in certain restricted ways.I mean thus to recall our criteria of existence and perdurance for snowballs.So much for snowballs.The like is true of chains and constituent links, boxes and constituent sides, and a great variety of artifacts or natural entities such as hills or trees; and the same goes for persons and their constituent bodies.In each case we have criteria of existence and of perdurance, an entity of that sort existing at t (perduring through I) if and only if its criteria of existence are satisfied at t (its criteria of perdurance are satisfied relative to I).We are supposing a snowball to be constituted by a certain piece of snow as constituent matter and the shape of (approximate) roundness as constituent form.That particular snowball exists at that time because of the roundness of that piece of snow.If at that time that piece of snow were to lose its roundness, then at that time that snowball would go out of existence.Compare now with our ordinary concept of a snowball the concept of a "snowdiscall," which we may define as an entity constituted by a piece of snow as matter and as form any shape between being round and being disc-shaped.