Metaphysicians who do ontology argue about what things are fundamental or real or exist: for example, in what sense do tables and chairs exist? do numbers exist in the same sense? are collections of things like your-house-and-your-left-ear just as real as your house or your left ear? Or, for example, is a statue made of marble one thing (a statue made of marble) or two things (a statue and some marble)? Some philosophers argue that ontological questions are pointless or merely verbal. Some philosophers disagree. This book has sixteen recent essays that are intended to explain what ontology is, how it should be done, and whether it should be done at all. 

My favorite essay in the book was “Answerable and Unanswerable Questions” by Amie L. Thomasson. Professor Thomasson argues that many metaphysical or ontological questions cannot be answered. For example, they presume that there are reasonable criteria for deciding whether numbers or propositions are things in some supposed neutral or generic sense of “thing” that can be applied to numbers and propositions just as well as it can be applied to dogs, tables or elementary particles.

She correctly points out that it makes no sense to ask whether something is a thing unless we already know what kind of thing it is supposed to be. We should all agree that numbers exist, since we can all identify numbers, such as the number 3. But we cannot say whether the number 3 is a thing in some more general sense, since there are no agreed-upon criteria for identifying things in that more general or neutral sense.

It seems that the only interesting ontological questions are whether it is more coherent or consistent or helpful to categorize various things as existing or real or fundamental. There is a lot of agreement about what exists, but not about which words should be used to say what exists.  (6/25/12)