[xtagon]

In ontology, you can think of the concept of "table" as being a role that an object can fulfill (possibly for a given period of time) rather than strictly a specific class of object. For example, let's say you move into a new home and haven't set up all the furniture yet, so you temporarily use a crate as a table. Even the phrase "as a table" suggests that it's more of a role than a class. If a crate can be a table, and a crate has no feet, what makes a table with feet more of a table than that? It serves the same utility and can naturally be described as such in conversation.

By that line of thinking, the essence of a table may have very little to do with it's shape, and more to do with it's purpose. But I can see how that just opens up a new rabbit hole to go down...