ABSTRACT
There is a great deal of literature on the relationship between judgements of depth and other properties of perceived things. The non-depth properties that seem sufficient for depth include: motion and Uniform variation in width and height. Stereopsis is the sense of depth brought about by what is seen through two eyes. If one includes a sincere phenomenological description of how thing seems, in the case of what is apparent, one includes the phenomenology of stereopsis. If Mac Cumhaill is right, the appearance of seeing through empty space requires the appearance of depth. The appearance of depth is an appearance of things at different distances to us in the external world. That is, the appearance of depth is the appearance of varieties of external distances. The visual phenomenology of depth seems only to depend on what is visible.
