 As for the common belief that objects of sense perception have external existence, it is said to arise from little more than the implicit reasoning that refers sensations induced by the sensory system to objects that continue to exist. The addition is that the sensory organs are supposed to act mechanically, to have contact with objects with which they join in causing sensations. The mechanical character of the interaction of sensory organs and objects of sense perception is taken to imply that the objects can be perceived by conjunction with the sensory systems of more than one human being if more than one exists. 