Regardless of words being context-dependent and having uncountable number of meanings, in the context of a single argument a word should generally only have one meaning.

Again, I could not disagree more with your interpretation of what's happening here.

I'd recommend you, too, read the article I linked in the comment above. To characterize Wallace's words as an "argument", as if he were a lawyer in the court of being—as if such a thing exists—, is to employ cognitive decoupling, and to miss the point.

There's nothing wrong with C.D.—it's absolutely useful and necessary to have contexts in which words mean one thing and one thing only, but it's equally if not more necessary to have contexts in which that constraint does not hold, in which we are free to make meaning by use of metaphor and non-literal comparison. Indeed, it's the only way in which we can point to dimensions of experience that do not yet have names; it's how language evolves and expands, it's how technical domains come into existence.

If you are writing a research paper or a legal contract, yes.

I think that's the thing that people on this thread aren't getting: he's not making an argument!

That article is 6000 words long, any chance you can summarize?

At the risk of being uncharitable, "you're using cognitive decoupling" is roughly equivalent to "you're using logic".

Sounds like the usual post-modern rubbish to me...