An Entity is the Sum of its Parts

One difficulty in applying the Law of Identity to an entity is in discussing what exactly an entity is. This is important to the concept of change, which is a subset of causality. Assuming there are basic building blocks of the universe, it is conceivable that these entities have a fixed identity, except location. They do not change. They act, and interact, but do not ever actually change their identity.

Other objects do change. A log can burn. A plant can die. A cookie can crumble. Their identities appears to be unstable. This isn't true, of course. Their identities are changing according to their identities, and the causal interaction that is occurring. So it is clear that even entities composed of other entities have identity.

It is important to note, though, that their identities are based on the identities of their constituent parts, and how they are combined together. The identity of an entity composed of other entities can be fully explained by reference to the identity of the building blocks, and how they are interacting. A house can be explained by reference to the wood, metal, and glass that are combined in that particular way to form the house. Or it could be explained in terms of the atoms that form it. These are all true, because the entity is a sum of its parts. Depending on what we specify as an 'entity', it has a particular identity. This identity exists objectively. We may choose to focus on a particular part of an entity, and discover the identity of that part, but it doesn't contradict the identity of the whole.

Copyright 2001 by Jeff Landauer and Joseph Rowlands