 Another important recent contributions to the philosophy of color is the book by Matthen (2005). In this work, Matthen articulates a theory of sense-perception in which color plays a prominent role. The work is significant for the theory of color that he presents, one that draws heavily on comparative studies of color vision among different species. Matthen replaces his earlier objectivist views on color by an account that has more in common with the ecological theory favored by Thompson. Matthen agrees with Hardin, Thompson and others that the phenomenology of color is not captured, or accounted for, by any of the standard objectivist accounts. Nevertheless, he claims to be defending a realist theory of color and to be rejecting standard irrealist theories, including Hardin’s. Matthen’s account is complex. The idea is that the senses (the visual sensory system) do categorize objects as “blue”, “yellow”, etc., but these qualities are related to actions that perceivers can perform, and in particular, to “epistemic affordances”. The sensory systems are held to be devices that are in the business of classifying distal stimuli (physical objects) as having certain properties, which stand in similarity and difference relations with each other. These categories are constructed by the system and do not, at least in the case of color, correspond to any objective properties that are independent of perceivers.