Now, it could be a lifelike photo, or I could be looking at the real thing. What is the real thing? A real apple would be 2-8 inches across, solid, but soft, three-dimensional, and be filled with organic compounds, show signs of organic growth, and so on.
We would agree that the apple is "real" if the 2-D pattern we first observe is part of the extended 3-D pattern of phenomena I just described.
Well, this is what "real" means. We don't require apples possess invisible properties in invisible dimensions. The reality of the apple is fixed in our experience. If we believe the proposition "this apple is real," then we have an expectation that the apple is 3-D, solid, organic, etc.
Thus, when we say that "the apple that is sitting on the table is real," we are using a code that means that our experiences will be in accordance with our conventional definition of an apple. The apple will participate in our experiences in expected ways - it won't walk away, spontaneously disappear, it will rot if we go on vacation for a week, and so on.
Unfortunately, the situation isn't even this simple. If I find that the apple has no seeds in it, I will be faced with a choice. I can declare that the apple is not a "real apple" (since I have ever seen a seedless apple) or I can extend my definition of "real apple" to include seedless apples. Through a lifetime of experience, our definitions of "real stuff" have been so defined, often in a subjective way. (People disagree as to whether certain species of banana are actually bananas at all. "That's not a real banana," they say.)
I am saying that "real apple" is a mnemonic for a pattern of experiences we have associated with apples. It is not the case that an apple is only real if it has some "unexperiencable" property. No. Any apple that our experience tells us is real is real by definition.
This means that, 99.9% of the time, substance theorists and bundle theorists have the very same intuitive sense of reality. Galaxies, big bangs, hamburgers, and politicians are all equally real to us both.
However, there's a strong (and quite natural) psychological desire to say that reality is more than this. There are several reasons why.
- The list of patterns of experience that constitute a "real object" is far more extensive than we can think of at once. If I were to ask you to list all of the attributes of cars, and define the boundaries of what is and is not a real car, you would be at it for a whole week. Throughout our lives we constantly evaluate whether X is a real car, and if X is sufficiently car-like, it gets incorporated into the definition of "real car" even if X is fairly bizarre (e.g., lowriders).
- We are often in a position in which we are fooled about real stuff, and another person isn't. We can be swindled. We can be confused in such a way that another person is better informed than we are about what is real. It is natural to feel that, since there are cases in which other people are better informed than ourselves, there must be some frame of reference in which the definitions of what is real are absolute and observers are impartial.
This is the cognitive equivalent of believing in an absolute rest frame. We're so used to thinking about things being at rest in everyday activity, that we are compelled to believe in a frame which really is at rest, even if we're not sure how to find it or define it. Special Relativity showed that this intuition was unjustified, if not wrong.
For me, the "real apple" is an intersubjective definition of a pattern of phenomena. If experience demonstrates these phenomena, then the apple is real. If it doesn't, either we refine our definition or the apple isn't real.
For substance theorists, if the apple is real, it exists in a fashion that has nothing whatsoever to do with any experience they will ever have. I think this is psychologically natural, but ultimately an inconsistency because reality isn't defined in terms of stuff we don't experience.