Professors Firth's “Sense–Data and the Percept Theory” examines a disagreement over the nature of visual experience. Those in the traditions of British empiricism and introspectionist psychology hold that the content of visual experience is a sensuously given mosaic of color spots, together with a mass of interpretive judgments injected by the subject. Firth calls this the Sense–Datum Theory, but I shall call it the Color–Mosaic Theory (since the opposing theory also accepts something we might call a sense datum). Those in the newer traditions of linguistic phenomenology, Husserlian phenomenology, and Gestalt psychology agree that visual experience consists rather of sensuously given percepts - presentations of ostensible constituents of the external world. Firth calls this the Percept Theory, as shall I. He himself is one of a growing number of epistemologists who accept it.

As we shall see in the next section, Firth shows how the difference between the two theories may be stated as a disagreement over a certain thesis: the Exposure Hypothesis. Color-mosaic theorists implicitly accept the Exposure Hypothesis; percept theorists such as Firth reject it.

I claim that the Exposure Hypothesis, properly understood, does not conflict with Firth's Percept Theory. I shall propose an interpretation of the Exposure Hypothesis and the central thesis of the Color–Mosaic Theory within the terms of the Percept Theory itself. If I am right, disagreement over the Exposure Hypothesis is not disagreement over the nature of visual experience, but only over the value of a certain way of speaking.