Some of Descartes’ critics argued that he may as well have said something of the form, Ambulo Ergo Sum, I walk therefore I am. If an entity walks then it quite clearly is. It simply has to be. But are there any examples of properties we can ascribe to a being that we cannot derive existence from? Let’s look at some candidates:
I am possible.
I am impossible.
I am perceived.
I am conceived.
Now the vocabulary has changed slightly with some of these terms. We ought now to shift “existence” to “actuality”. My position has to be that “everything exists”, but only some things are actual. It clearly doesn’t follow that because something is possible it must be actual. If we were to re-phrase Descartes’ argument it would go as follows:
I actually think, therefore I actually am.
But is the following argument valid?
I am actually possible therefore I actually am.
I don’t want to reject this too hastily. In terms of modal logic it fails tremendously, but perhaps we can admit entities that are merely possible into our ontology for the actual world, in the form of an accessibility relation. If X is possible then it is true in the actual world that there is some world w such that @Rw and vw(X) = 1 even when v@(X) = 0. Is the accessibility relation between @ and w a metaphysical part of @, or is it somehow outside? Well, we seem to know about these relations, although that’s not a great argument that they are inside. I think if anything this is somewhat of an argument for Ersatz Modal Realism. I will continue to think about this though…
On to the second two candidates. This is now a different subject. I think I want to just work out the meanings of the words “perceive” and “conceive”. We take it as true that we can actually conceive Santa Claus, but that does not entail his actuality. It does not even necessarily entail his possibility. Lewis gives us the example whereby we can conceive a world where there is a largest prime (and people have believed such things), but those worlds aren’t possible. (The alternate, he says, is where we cannot conceive worlds with 10 dimensions, but they are possible). I’m not sure what to make of this right now.
I am reasonably certain now that if an entity is perceived then it must be actual. Suppose a child sees somebody dressed as Santa and they say “I perceived Santa”. Is that statement true? I think not. The child is stringing together thoughts like the following:
1. I perceived X
2. X is Santa
3. Therefore I perceived Santa.
The mistake is with the identification of the thing they saw with Santa. They perceived something other than Santa. Is it the case that for there to be perception there has to be a percept? I’m not sure. One might say that we perceive even when dreaming, but then we are really still perceiving things that are in our memory. There surely has to be some kind of causal stimulus, so I will conclude for now that there does have to be a percept if there is perception, and for it to be true that you perceived X, X must have been the percept of your perception, and not some thing, Y, such that you falsely believe that X=Y.
