the bike of John is John’s bike
the view of the politicians is the politicians’ view
the room of the men is the men’s room
the theory of Rawls is Rawls’s theory
and not Rawls’ theory, or at least, that is what I always thought. My question to you is, is this spelling correct and who if anyone uses it? Is it a UK-US thing? Please fight my ignorance
Unless the additional ‘s’ makes for an awkward pronunciation. For instance, you don’t usually see ‘Jesus’s teachings’. You can avoid the entire mess by saying ‘the teachings of Jesus’.
Hmmm, I’m sure that way back when I did have to study Rawls, I used "Rawls’ " as the possessive form, e.g. " … in Rawls’ “A Theory of Justice …” etc, but if I was wrong about that, I suppose that was probably the least of my worries at the time.
Of course that was at St. Andrews University, which tends to suffer from a lot of people incorrectly adding an apostrophe, so perhaps confusion was in the air.
I seem to recall two “rules” though I don’t see them documented anywhere:
Most singulars ending in -s take -'s to form the possessive. The exceptions are:
Classical names take a lone apostrophe. “Achilles’ heel”; “Good friend, for Jesus’ sake forbear…”; “Judas’ betrayal”; “Euripides’ Trojan Women.”
Singular nouns where the spoken form ends in /-Iz/ (the actual symbol there being a small capital I with a horizontal bar midway up) take only the apostrophe.
For the larger question, the important quote is buried in the Chicago Manual quote:
As long as you are consistent within a document, you can form possessives in any way you like. Add an s, don’t, it’s up to you.
This changes if you are in a formal situation that calls for reference to a style guide. But if you’re in that situation you can’t ask the question in the first place.
It’s a matter of style. There are no rules to style except the one of consistency.