Full Idea
If Tully=Cicero is synthetic, the names must have different senses, which seems implausible, for we don't normally think of proper names as having senses in the way that predicates do (we do not, e.g., give definitions of proper names).
Clarification
Cicero, the great Roman writer and orator, is also known as Tully
Gist of Idea
We don't normally think of names as having senses (e.g. we don't give definitions of them)
Source
John Searle (Proper Names [1958], p.89)
Book Reference
'Philosophical Logic', ed/tr. Strawson,P.F. [OUP 1973], p.89
A Reaction
It is probably necessary to prize apart the question of whether Tully 'has' (intrinsically) a sense, from whether we think of Tully in that way. Stacks of books have appeared about this one, since Kripke.