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Our panel of 90 professional philosophers has responded to

Question of the day

Your distinction between something not yet defined and something for which there could never be a definition is a reasonable one, and thus an answer that bears only on the former doesn't answer your question.

Here's one possible approach. If something exists, it has some properties or other; for every property a thing might have, the thing either has it or it doesn't. If that's right, then we might say that nothing could be that thing unless it has that set of properties. And in that case, we might say that the set of properties "defines" the object, whether or not any finite list could capture all the properties.

That's a rough sketch. It would need careful spelling out and it would also be subject to various objections; leave those aside. The point is that if we look at things this way, the notion of "definition" we're appealing to needn't have anything to do with how limited creature like us get a grip on the object. If this line of reasoning is correct, then nothing could exist unless it had a definition, but things would have "definitions" in this sense whether or not anyone knew or could know those definitions.

What if we insist that a definition must be something a finite knower could grasp? In that case, it's hard to see what connection there would have to be between existing and having a definition. The world in all its complexity was around long before we arrived and will still be around long after we're gone. Why think that what we (or our evolutionary successors) can grasp should limit what there can be in the world itself? Thus, if definition is what we might call an epistemic notion (a notion having to do with what we can know), then it might very well be that some of the things that exist can't be defined.