TheExistenceOfPhysicalObjects

<The following is a portion of LarrysText, wikification is encouraged>

What does it mean to say that a physical object exists? Take for granted, for the time being, that one knows what a physical object is. The question is what it means to say that that sort of being exists. Or, if one prefers, one may fill in the blank in the following: "An object exists, if and only if, it ... ." That would give one a definition of the word "exists" in the sense in which that word applies to physical objects.

Some have thought that this question cannot be answered. It has been suggested that "exists" simply cannot be defined. That people very well understand what it means to say that an object exists is not necessarily to say one can define it. This is a very influential view, which many very smart people hold. But the initial assumption will be made here that we can define "exists" for physical objects.

Here is a starting point for this assumption. What is existence constrasted with? Well, nonexistence; but there are different kinds of nonexistence. Think of all the different ways that something talked about nevertheless fails to exist. For example, in stories: Romeo and Juliet do not really exist, because they are merely characters in a play. So there is fictional nonexistence. Or suppose one is just daydreaming and one imagines winning the Nobel Prize. Well of course this Nobel Prize does not exist: it's just imaginary. So a second kind of nonexistence is imaginary nonexistence. (Or you might say, "It has existence only in one's imagination.") Or consider that old hypothesis, that the Earth is flat. People who thought the Earth was flat thought there was an edge to the world, and if one sailed too far across the ocean one would sail off the edge of the world. Well, the world is not flat but roughly spherical, and the edge of the world doesn't exist. So that is a third kind of nonexistence: hypothetical nonexistence. In other words, that's the sort of nonexistence that false posits have, when one posits something in a false hypothesis. And now here's a totally different kind of nonexistence: namely, the kind the ancient Greek philosopher Socrates now has. Socrates does not exist now. He did exist, but there's a sense in which he doesn't exist; namely, he doesn't exist any longer. So the fourth sort of nonexistence is past nonexistence. And of course then, fifth, there would have to be a corresponding future nonexistence. The person who will be President of the United States 200 years from now does not, now, exist.

Hopefully this gives a very vivid idea of what it is that one is talking about when one says that a physical object exists: it's actually in the world, it's not fictional; it's real, not imaginary; it's an actual phenomenon, it's not part of a false hypothesis; and it's located at the present time, not just at a past, or a future time.

There may be many different senses in which objects can fail to exist; but it would appear there is only one basic sense in which physical objects actually do exist, and that is as an object that belongs to the space-time system that is the world with which people are in direct contact. If one can bump into it, it exists. So one might boldly give this following definition:

Physical object O exists if, and only if, O is, at present, spatially located in the universe with which we are in contact.

This is a plausible definition of "exists," one that expresses the common sense notion of existence. But it's just an attempt, of a sort that a few, but only a few, philosophers have given. [Aune], for example, gives a definition much like this one. Suppose one is in a room with a big red apple. According to this definition, to say that that apple exists is just to say that right now, it has some location in space, that is, in the space that one's body is also part of. So in other words one is at some distance from the apple right now. That's approximately what it would mean to say that the apple exists.

Consider how it is that those five different kinds of nonexistent objects fail to exist according to this definition. First, fictional characters. In fact, Romeo is not spatially located anywhere. So he doesn't exist. Second, imagination. The imaginary Nobel Prize is not located anywhere in relation to the observable universe. So it doesn't exist. Third, false hypotheses. Well, the edge of the world is not, in fact, located anywhere in the world; the world doesn't have an edge. So the edge of the world doesn't exist. Fourth, past and future. Socrates from ancient Greece, and the President in the distant future, are not at present located anywhere in relation to the observable universe, not at present.

As one might suspect, this sort of definition encounters some serious objections. Consider the following objection, probably the most widespread.

There are many philosophers today, following Kant and Russell, who claim that existence is not a property. This is a rather strange thing to say. Now, the writer of this article exists, and the Eiffel Tower exists. These are both true claims, and they both make perfect grammatical sense. It seems like the author asserts that existence is a property of himself, and of the Eiffel Tower. And yet many -- not all, but many -- philosophers deny that existence is a property.

First of all, One might wonder why it matters at all whether or not existence is a property. Consider: if existence isn't a property, then the concept of existence cannot be defined, or at least, not the ithas been defined here. The foregoing definition of "exists" is incorrect just because the definition does treat existence as a property. It starts out by saying "Physical object O exists if..."

Many people have said that the influential German philosopher [Kant] had an argument with the following conclusion: existence is not a property. In an effort to expain this: Suppose one listed out all the properties and relations of the aforementioned apple. It's red, it has a stem, it's four inches wide, it's juicy, it's on the table, it's in the room, and so on. Kant says, then, once one has listed out all the properties and relations of the apple, one could try saying that the apple exists. But that wouldn't add any new property to the thing, Kant says. Therefore, existence is not another property over and above all these. So in other words, Kant argues as follows: a complete list of an apple?s properties would not be expanded by adding another property, namely existence; therefore, existence isn't another property over and above all the other properties.

So -- does that mean that existence is not a property at all? Well, no. If one lists out all the properties of the apple, the list would include "being located in the universe with which we are in contact." That particular property just is what makes the apple exist. That property would, of course, be included in a list of all of the apple's properties; so then consider this claim of Kant's, that existence isn't another property over and above all its other properties. Well, that's right, it's not another property. But that by itself doesn't mean that existence isn't a property at all! So Kant's argument just doesn?t appear to prove its alleged conclusion.

Consider also how [John Hospers] interprets Kant's argument. Maybe Hospers can make Kant look better. To quote Hospers:

"If we say that a horse has a mane, a tail, four legs, and hoofs, we are attributing properties to the horse; but if we go on to say that the horse exists, we are not adding another property: we are saying that the thing we conceived as having these properties also exists. We are not adding to our concept of the thing: we are asserting a relation between the concept and the world."

Hospers says here that when we say that a horse exists, we aren't attributing a property to the horse; we are "asserting a relation between the concept," the concept of the horse, "and the world." That's what he says; but on further reflection, one can see that it's not quite right. To say the horse exists isn't to assert something about the relation between the concept of the horse and the world; it is to assert something about the relation between, well, the horse and the world! Namely, that the horse is in the world! And one can have a concept of a particular horse that exists, and that concept would have that horse located in the observable world; and one can also have a concept of a particular horse that doesn't exist, and that concept would have that horse not being located in the observable world. So again, Hospers' argument apparently isn't valid. It just doesn't prove that existence isn't a property. All that it proves -- and it does prove this -- is that existence isn't a different property from the other properties of a thing.

But the dialectic definitely doesn't end there. Much more can be said on both sides. To really get to the heart of why so many philosophers these days think that existence can't be defined, one would have to explore much more logic. Present time and space do not permit this.

/Talk