I think what he meant is that 2+2=17 is at least right in the "domain of knowledge", that is in arithmetics, the answer should be something that represents a number.
> You can't argue it
I'll argue it. :) If you take the 7 and lower the top line, and take the 1 and make is smaller and place it on top of the line to the left, you have a 4.
But there's something to be said for the math example, and I know I'm pedandic, but 2+2=17 is probably more wrong than 2+2=purple.. There's going to be no way to explain how you arrive at 17.. You can't argue it.. You could argue however that, "Oh, purple, sorry, well, four always tasted like purple to me, so that's the one I jotted down in a rush"