Opaque context
An opaque context is a talking situation where you can’t always swap two different names for the same person without changing the truth of what’s being said. The names are usually single words referring to the same thing, but in these contexts the way the name is used matters.
Example: Lois believes Superman is a hero can be true, but Lois believes Clark Kent is a hero can be false, even though Superman and Clark Kent are the same person. The belief is about how Lois uses the name, not just about the person.
In contrast, a transparent context lets you swap co-referential names without changing truth. For instance, Cicero was a Roman orator and Tully was a Roman orator are both true if Cicero and Tully are the same person.
In opaque contexts, substitution can change the sentence’s truth. For example, if Mary believes that Cicero is a great orator, we can’t simply conclude that Mary believes that Tully is a great orator, because Mary might not know that Cicero and Tully refer to the same person.
This idea is used in philosophy of language to discuss how names work, especially in theories that treat a name’s meaning as just its referent. It also appears in programming languages and other formal systems, where the way a term is used can affect meaning beyond the bare reference.
This page was last edited on 2 February 2026, at 08:08 (CET).