Grice on "∵" and "∴"

by JLS
for the GC

--- WE ARE ALL FAMILIAR WITH "∴", which is all that Grice's third book is all about: Aspects of reason. "∴" reads 'therefore', and Grice has written extensively on its conventional (rather than conversational implicatum). What is less known is its inverse, which the wiki has as a premise sign:

Under 'therefore' entry:

"It would also be proper to indicate a
premise with the because sign. For example:
∵ All men are mortals. ∵ Socrates is a man. ∴ Socrates is a mortal."

Unless it's improper, of course.