As I understand, magnetic materials (ferromagnets, paramagnets and diamagnets) appear due to the polarization of it atoms or molecules. In other words, they exist because their atoms or molecules are polarized. This means that every magnet is just a consequence of the existence of electric dipoles.
From this statement it seems obvious that there cannot exist a magnetic monopole, since the very definition of magnetic field needs a dipole to be there. My question is, why then postulate the existence of a magnetic monopole? How would a magnetic monopole be different to a single electric charge?