Everyone is familiar with the concept that the cube and octahedron, dodecahedron and icosahedron are dual pairs, with the tetrahedron being self-dual. On the face of it, the concept seems straightforward; however, in all but the most symmetrical cases it is far from clear. By using the computer and three-dimensional graphics programs, it is possible to clarify the concept and explore new ideas. Moreover, it is an ideal topic for teaching clear logical thinking. (Contains 21 figures.)