Hilzoy, I’ve got a paper on my desk by one John Christian Laursen, “The Subversive Kant: The Vocabulary of ‘Public’ and ‘Publicity’” (in What is Enlightenment?, an anthology edited by James Schmidt, University of California Press, 1996). He argues that, by the standards of Kant’s day, it would have been weird usage:

“Kant’s usage of ‘public’ to refer exclusively to writers and the reading public is striking today, and it would have been in Kant’s day, too. We are accustomed to thinking of a career in civil service as part of our “public life” and any writing that we might do evenings and weekends as our own private affair. As any scholars have noticed, kant turned this meaning around. I shall explore sources for this alternative usage below.”

He does so. “By the eighteenth century, the process of reduction of “public to “pertaining to the state” had reached a high point among legal writers.” For examle: “In 1762 the jurist Georg Wiesand wrote that res publica, including everything from rivers, forests, and salt licks to light and water, belong to the prince. They were ‘public’ not because they were out in the open or of general use but because the prince claimed to own them.”

In view of this sort of usage, Kant’s is alleged to be highly provocative, although he is not alone. Usage by Lessing, Wieland and others is cited.

I have no opinion about it, really. But apparently at least some scholars think it really was a ‘cunning reversal’ of sorts.