Abstract

Ordinary common sense suggests that we have just one set of shape concepts that we apply indifferently on the bases of sight and touch. Yet we understand the shape concepts, we know what shape properties are, only because we have experience of shapes. And phenomenal experience of shape in vision and phenomenal experience of shape in touch seem to be quite different. So how can the shape concepts we grasp and use on the basis of vision be the same as the shape concepts we grasp and use on the basis of touch? I think this is the intuitive puzzle that underlies the question sent by the Dublin lawyer Molyneux to John Locke. This concerns a man born blind, who learns by the use of his touch to discriminate cubes from spheres. Suppose him now to gain the use of his sight. And suppose him to be presented with a cube and a sphere, of nighly the same bigness. Quaere, will he be able to tell, by the use of his vision alone, which is the sphere, and which the cube? (Locke 1975, II/ix/8.)