Riddles

I have a riddle for you. Don't worry, it's not meant to be particularly hard or anything. It's merely an exploration of the definition of the word riddle, and how one can apply it to reasoning. Ok, ready? Here it is:

How many ducks?

The answer: As many as there are.

So, did you think of the answer? Did you consider it? Maybe you don't think it's really a riddle at all.
Actually, that's a fairly serious problem I'm having with this. A friend argued that it wasn't. I disagreed, and he thought I was merely being argumentative for the sake of which. I don't blame him, given that I enjoy being argumentative, but, in this case, I was being entirely serious. However, I can't just drop his case right then and there. I considered it a very serious problem to consider, especially since it questions the very definition of a riddle itself.

What his basic case against my riddle was this: to any other riddle, the answer I give would be completely unacceptable. If you told a sphinx, "Something that walks on 4 legs at dawn, 2 at noon, and 3 at evening", you would get summarily eaten. If you said, "whatever that is in you pocket" to Bilbo, he probably would have scoffed, and for good reason.

But, then, what makes the "proper" answer to a riddle better than the rest? Part of the structure of the average riddle is being intrinsically vague, so that you have to use conjecture in order to solve it. You could frame many answers to the sphinx's riddle that would be technically correct; in fact, the real answer doesn't even fit the definition of technically correct anyways, since the entire presupposing relies on the ability to realize the question in terms of time is making a metaphor. After all, human beings don't really start out every day on 4 legs, noon on 2, and evening on 3.

Therefore, what makes the Sphinx's answer better? It's certainly not the most clear explanation, and if you actually found some person or some creature that fit the definition more perfectly, the sphinx still wouldn't find your answer correct, even though if you weighted the quality of the answers, yours would be considered superior. The problem, really, is that a riddle is, in part, only correct when you guess the thing the person thought of when framing the riddle.

But my friend believes there is apparently some fundamental rule behind the structure of riddles that makes it so you have to have that level of obfuscation, and cannot simply restate what the question said. He equated it to an XKCD comic: http://xkcd.com/169/

He equated as such because he believed the fundamental nature of the question betrayed some sort of definition of riddle by being misleading in that its not answered in the same way in a conventional riddle.

That's not what I believe. What I believe is this: Restating the question of a riddle as it is stated as an answer is, by all definitions, correct. It is, however, not what the asker wants in most cases, even if, when pressed, the asker would admit is technically true. The real problem is that, for the average riddle, there is an expectation of not what is correct, but the answer that the asker wants. By relieving that standard on my own riddle, I break expectations of what a riddle can be, but not breaking what a riddle is in and of itself.

And yes, if you're wondering, people have looked at my riddle and guessed the right answer in one or two tries. So it's definitely not impossible.