 Denis Robinson (1993) raises the possibility that Lewis’s argument can be extended to produce a far-reaching and puzzling result. Suppose that \(I_1\) and \(I_2\) are two possibilities for an intrinsic property of a basic physical entity, e.g., a quark. Everything relevant to physics can be expressed by the lawlike relations in which quarks stand to fundamental physical objects and properties. Let this set of relations be \(\mathbf{S}\). It appears that there are two possibilities, (a) \(I_1\) is related by a set of laws, \(\mathbf{L_1}\), to \(\mathbf{S}\); or (b) \(I_2\) is related by a different set of laws, \(\mathbf{L_2}\), to \(\mathbf{S}\). Either of these possibilities is compatible with all the physics we have, i.e., their difference makes no physical difference. Thus, that the intrinsic property of quarks is, say, \(I_1\) rather than \(I_2\) can make no difference to physics, i.e., \(I_1\) is epiphenomenal. The generalization of this point is that the intrinsic properties of the fundamental objects of physics must be epiphenomenal.