Suppose Joe Shmoe died on February 17, 1982, sadly leaving no relatives or friends behind. Every year, on February 17, the anniversary of Shmoe's death occurs. No one marks it in any way. But it occurs, every year, invariably. It is what one might call a Cambridge event, whose occurrence does not mark any real change in the world.
Similarly, there seem to be Cambridge objects. Just as the anniversary is defined by a certain temporal distance, we can define an object by a certain spatial distance. For instance, let me introduce an object: my visual focus. My visual focus is a moving object a certain distance in front of my eyes--sometimes moving very fast (in principle, a visual focus could move faster than light!). My visual focus is a persisting object, unless I close my eyes (I am not sure whether it persists when I blink or just blinks out of existence). Curiously, my visual focus, while typically having a spatiotemporal location, could also exist outside of spacetime. Imagine that I am focused a meter ahead of my nose, and space has an edge. I walk towards that edge, unblinking and never refocusing, rapt in thought about ontology. Before my nose touches the edge of space, my visual focus will have moved beyond it! We can say that the visual focus is "a meter ahead of my face", but that isn't an actual place. So we cannot identify the visual focus with a whole made up of spacetime locations.
My brief remarks have taught you, I think, a little bit about how to talk about visual foci. You now know roughly when my, or your, visual focus exists. You know something about its persistence conditions. You know a little bit about what predicates apply to it. And there is a vast range of stuff that's as yet underdetermined, and could be determined in more than one way. For instance, how wide is the visual focus? Does it shift very quickly with saccades?
But of course it's also clear that there has to be a sense in which there really are no visual foci. Objects that can leave our spacetime so easily, that can move faster than light, and that are entirely outside us but are entirely grounded in our state just aren't really there. They are Cambridge objects instead of real ones, akin to Cambridge events, Cambridge properties and Cambridge changes.
This post is inspired by John Giannini's dissertation.
7 comments:
The question is what you mean by "really".
And even if there is some sense of "really" in which they are not really there, there are other senses of "really" in which they are really there.
I think what you want to say (judging from the other post on fundamental entities) is that there is one, true, fundamental sense of "real" which includes things like people and maybe fundamental particles, but not things like desks.
I think that's obviously wrong. "Real" is irreducibly said in many ways, and we cannot find a most true and fundamental way (or if we can, God alone exists in that sense, and not even things like people).
Joe Schmoe's death may not mark any change in the world. On the other hand, Veteran's Day is an anniversary and it does mark changes in the world. It causes things to happen, you might say. Does that mean Veteran's Day, but not JS's death anniversary, is a "real" event?
Suppose then we construct a similar situation for a visual focus. Anytime the king's visual focus coincides with a person, they bow. Does that mean that the king's visual focus, but not mine, is a real object?
(My larger point is this. I think the highlighted sense of "really exist" you are using is approximately that X really exists iff X explains something. The above two cases are test cases. If I am right, I would say that the question of what "really exists" is better approached by asking what explains what, and leaving ontology out of it. Metaphysically speaking, all anniversaries are alike and so are all visual foci.)
I'd distinguish between anniversaries and observances of anniversaries. It's the observance that has causal efficacy. The king's visual focus has no effects: it's the position of his eyes that causes things. I think the annniversaries as such are all on par, and ditto the visual foci.
I would be happy with an ontology that said X really existed iff X had an effect. That would be a clear enough sense of "really exist." Of course, I worry that there will be an immediate question about whether something "really caused" something else.
P.S. What causes observances of anniversaries, if not ... anniversaries?
Clocks and calendars? Or the particles/fields constituting them? People's memories?
Wouldn't God exist, even if He chose not to create or do anything?
Probably a better view (not one I am endorsing) is that something is real only if it is capable of having an effect.
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