If the discussion is about A, and, let's suppose, some P(A) is true, if P(B) is also true, but discussion never mentions B - what's the point of solely bringing the fact of truthfulness of P(B) into the picture?
Fair point. However, I didn’t get that impression at all - in my reading the preceding conversation didn’t seem to suggest anything about uniqueness or make any comparisons. Would you mind quoting the piece that made you think it’s suggested so, please?