Strictly speaking, MD's are mere technicians, especially surgeons. MDs know the symptoms of the diseases and know what medicines to give, which by the way are discovered mostly not by the MDs but by PH. Ds.

PH. D.s are policy makers, thinkers, researchers, scholars, social engineers, teachers, and philosophers. There is no PH.D degree without research and without research a PH.D. can not survive in his/her occupation. Higher education depends heavily on PH.Ds. Their function to society is multi-faceted unlike the MD's unidimensional.