The other day a bizarre question popped into my mind: Is zero a number?  On one level, the answer is obviously yes.  Zero is not a letter, a flower, or a molecule.  It is in the class of things we call numbers.  While zero might be considered a number for classification purposes, does it truly exist in the real world?  While I can point to three eggs and say, “Here are three eggs,” I cannot point to some X and say, “Here are zero Xs.”  Zero does not correspond to anything in reality, because zero signifies the absence of reality.  To say one has zero eggs is just a mathematical way of saying one does not have any eggs.

Of course, the same could be said of negative numbers like -1, -5, or -100.  These numbers have no correlates in the real world.  You will never find -5 apples.  Negative numbers exist only in the mind.  Of course, the same could be said of all numbers.  While I can point to three eggs, five cows, or 17 cups, in none of these cases will I have located the numbers 3, 5, or 17.  I will have only found instances in which a specific numerical value is exemplified by particular objects.