Not quite sure if this fits, or if it's even subtle, but it's one of my favorite quotes that's as truthful as it is paradoxical...
"...there are two kinds of people in the world. Those who believe there are only two kinds of people, and those who are smart enough to know better."
- Tom Robbins, (I forget which book, I think either "Cowgirls" or "Still life")
Just to get us started-- I know this will be knocked off soon enough, but it's a good warm-up. When I think subtle distinctions, I think medievals, and in particular the doctrine of double effect. So I nominate:
The moral difference between (a) intentionally performing an action with the knowledge that the action will bring about a particular effect and (b) acting with the intention to bring about that effect.
Can you dig it?
Maybe the distinction between properties being necessarily coextensional and being identical? Let me think on this.
FL, are you a real philosopher or a pretend philosopher?
I can dig it. Numerous recent commentators voted for bush with the knowledge that it would overturn Roe V. Wade and be delaterious to the gay community, but they didn't vote for him with the intention to bring about those effects.
I see these distinctions are going down a more mental route, but I was serious about phonation, goddamit. Can you hear the difference in the vowels between fleur and heure?
"So, people of blogdom, what is the most subtle distinction ever made?"
I have discovered a truly marvelous demonstration of it which this comment box is too narrow to contain.
Besides, you wouldn't understand it.
Oh, that one. No, I know about that one; I meant besides that.
Most people don't have a full complement of vowel sounds. I, for instance, can't hear the difference between the initial sounds of "Aaron" and "Erin", so to me that difference is pretty subtle.
My co-blogger Froz once had a child ask him, "Is that a real clown or a pretend clown?"
I don't know, watching Brian Dennehy -- who I believe is required to star alongside Judith Light in any television movie -- play John Wayne Gacy puts a whole new spin on the difference between a real clown and a pretend one.
another nomination: Heidegger's distinction between true and the truthful.
unsubtle, perhaps, but delightfully paradoxical -
i recent realized that it's a GREAT BIG small, small world
How about this one (in an actual discussion about the plays attributed to Wm. Shakespeare):
The plays were not written by Shakespeare, but a man named Shakespeare.
I can't think of an appropriate Henry James quote. But I'd start the search in The Sacred Fount, which was described by Rebecca West as
"a man expending more intellectual energy than Kant did in The Critique of Pure Reason, analyzing the events of a weekend party and trying to discern if, in fact, his fellow humans are any more interesting than a flock of sparrows."