Theory which treats declarative sentences (as against commands and so on) as pictures of facts (if true) or possible facts (otherwise). A notable example of the theory is Tractates (1921) by Ludwig Wittgenstein (1889-1951).
Each element in the sentence (bar certain connectives and so on) stands for something, be it an object or a quality or a relation, and so on; and the connectives and the way the words are put together correspond to the way the objects and qualities and so on are related in the envisaged situation.
The theory is thus a form of correspondence or relational theories of meaning analogous to naming theories of meaning for Singular terms. One objection is that it does not seem to cater for the difference between merely picturing a scene and stating that that scene is part of reality.
E Daitz, 'The Picture Theory of Meaning', Mind (1953); reprinted in A Flew, ed., Essays in Conceptual Analysis (1956)