Full Idea
The theory of descriptions gives a model of internalist intentionality, in that it describes cases where the thinkability of a belief does not depend on the existence of a specific object.
Clarification
The theory spells out the assumptions about existence in a sentence
Gist of Idea
The theory of descriptions supports internalism, since they are thinkable when the object is non-existent
Source
Tim Crane (Elements of Mind [2001], 4.36)
Book Reference
Crane,Tim: 'Elements of Mind' [OUP 2001], p.120
A Reaction
So what do externalists say about the theory? Surely a reference to 'water' can't entail the existence of water?