Definition
External Reference Semantics (or Semantic Externalism) is the view that the meaning or content of a term is determined, at least in part, by factors external to the speaker’s internal mental state. It opposes “Internalism,” which claims that meaning is entirely determined by concepts “in the head.”
Why It Matters
This perspective is critical for building AI that truly understands the world rather than just manipulating tokens. If meaning is only internal, symbols are ungrounded and meaningless. In human communication, recognizing external reference prevents “semantic drift” and ensures that our debates are about the actual physical reality we share, rather than just the definitions we hold in our heads.
Core Concepts
- The Twin Earth Thought Experiment: Proposed by Hilary Putnam. If a person on Earth and their exact physical “twin” on a Twin Earth both use the word “water,” but on Twin Earth “water” is actually a different chemical (XYZ) that looks and tastes the same as H2O, their words mean different things despite their identical internal states.
- Causal Theory of Reference: Saul Kripke’s idea that a name (e.g., “Aristotle”) refers to an object because of a “causal chain” connecting the speaker back to the original “baptism” of the object, regardless of what the speaker knows about it.
- Direct Reference: The view that some terms (like proper names or natural kind terms) refer directly to their objects without the mediation of a “sense” or “description.”