[Y_Y]

You're totally right, and this exactly the sort of thing Wittgenstein set out to show. The trouble is that people have an idea of what a "heap" is and what "evil" is and what "knowledge" is and a lot of philosophy is concerned with pinning down those notions or at least saying something concrete about them.

[jimwhite42]

I think the Sorites paradox may point to something specific about these kinds of ideas, which is not shared with the meaning of things like evil or knowledge. There's a page on it on SEP: https://plato.stanford.edu/entries/sorites-paradox/