I fear we are speaking at cross purposes (as if we couldn't tell!)
I dusted off my copy of Lost in the Cosmos (a brilliant work by a brilliant
writer), and re-read the semiotics essay.
Naturally, I found it irrelevant to my view! Naturally, I found off the issue!
Here, we have the "triadic conundrum" illustrated, don't we?
In sum: the question is not how the world of the "sign user" developed. It is
the appearance of the "sign user" himself (Percy himself termed this
appearance "as sudden as biblical creation"--just what I've been saying!) I
don't think Naturalism has the "sign language" to explain this. Which leads me
to posit the existence of a supernaturlistic explanation.
By the way, if you want to read a great essay by Walker Percy, read "Bourbon"
in Sign Posts in a Strange Land.
Jim