Any philosophy which undertakes the task of deriving the whole of reality from the givenness of the stream of experience necessarily encounters grave difficulties in giving theoretical justification to the common-sense conviction that the world is a public object for a plurality of subjects. The other appears within the flow of my experience not only as an object alongside other objects, but also as a body whose behavior seems to indicate the presence of an alien subject of experience. This implies that the other perceives me as belonging to the world of his experience. How is it possible to coordinate this fact with the methodological requirement of Radical Empiricism that all empirical reality, including the world of physical objects, other people and even my objective self, must be derived from the absolute givenness of my pure experience? James recognized that his Radical Empiricism might easily be misinterpreted as a form of solipsistic idealism, akin to that of Berkeley. Hence, he devotes two chapters of his Essays in Radical Empiricism to the question of how it is possible to establish that different subjects know one and the same world.