Sellars thinks that science’s aperspectival description of the empirical world is the measure of reality, but he is also committed to the indispensability of the concepts built into the first-person perspective that makes agency possible.  If those concepts were not involved in the regulation of our behavior, we would not be persons and could not engage in such activities as moral behavior or scientific research.  This is why Sellars calls for a stereoscopic vision in which the descriptive resources of the sciences are united with the language of individual and community intentions and the dualism of the manifest and scientific images is transcended.  