The Fundamental Theorem of Ontology: Not Everything Exists.

There may be some in the world population who, even if they understand the importance of other branches of metaphysics, hold no brief for ontology – the study of what exists and what it is to exist. Some are quite satisfied with, “Everything exists.” It is, of course, true in one obvious way that everything exists. To be included among the things of everything is to be. So understood “Everything exists” is  tautological.  There is, however, a way of asserting “Everything exists” so that it carries real content, indeed makes an important metaphysical claim. Once many years ago, I made just this claim, and was as wrong as wrong can be.

My position back then was that every candidate for existence did, in fact, exist. Unicorns, for example, existed after the fashion of mythical animals. So there was never any question of whether something existed.

In my sympathy for the trade, I did not think of this as putting ontologists out of business. There remained the job of working through all those different ways in which things exist. Does the past exist in a different way from the present or the future? Do mythical animals of legend differ from the fictional animals of children’s books, and do fictional character exist differently from a doubly fictional character, as for example the knight in the tale told by the wife of Bath? Of course there also remained the hoary questions in what respect universals exist or the number 7 exists and whether both or either are the same respect in which imaginary numbers or transfinite ordinals exist. The discussion should be, I then contended, about the way things exist, not whether they exist.

Then the end came. The Achilles’ heel of my theory was the round square. I at first brazenly asserted that the round square was not so bad. I even suggested a definition: the locus of all points equidistant from a given point at which its diagonals bisect at right angles. But in the end, I had to concede that to exist after the fashion of an impossible object is just not to exist at all. Saying that round squares exist cheapens existence down to zero.

In retrospect, perhaps I should have been convinced by slithy toves. I would initially no doubt have objected that, although we do not know much about toves, we do know that slithy members of that species gyre and gimbel in the wabe. So, surely, they have fictional existence of some foggy sort. Were I to have thought a little harder about it, however, I would have realized that my program was going to let any word or phrase that seemed to function like a noun generate a candidate existent. Then, by my unreserved generosity, the candidate became a thing actually existing in one fashion or another.  Blixbs, in addition to being rather hard to pronounce, do not, however, exist in any fashion whatsoever.