  So far Moore's dialectic is familiar. What is unfamiliar is his direct realist position, according to which sense-data are physical. This position avoids the problems so far encountered, but in order to accommodate false appearances Moore has to allow that sense-data may lack the properties which we apprehend them as having. It may be felt that in so far as sense-data are objects at all, this is inevitable; but Moore now needs to provide an account of the apparent properties of sense-data and it is not clear how he can do this without going back on the initial motivation for the sense-datum theory by construing these apparent properties as properties of our experiences. But what in fact turns Moore against this direct realist position is the difficulty he thinks it leads to concerning the treatment of hallucinations. In such cases, Moore holds, any sense-data we apprehend are not parts of a physical object; so direct realism cannot apply to them, and yet there is no reason to hold that they are intrinsically different from the sense-data which we apprehend in normal experience. This last point might well be disputed, and at one point Moore himself considers the possibility of a distinction between ‘subjective’ and ‘objective’ sense-data; but once one has introduced sense-data in the first place as the primary objects of experience it is not going to be easy to make a distinction here without assuming more about experience than Moore at any rate would have wanted to concede.