Does Plato succeed in demonstrating that philosophers make the best rulers?

In Plato's most famous work, the 'Republic', he puts forward the view that the ideal state, embodying the highest and best capabilities of human social life, can really be achieved, if the right people are put in charge: "There will be no end to the troubles of humanity...till philosophers become kings in this world, or till those we now call kings and rulers really and truly become philosophers, and political power and philosophy thus come into the same hands" (473d). In many ways it can be seen that the strict and rigorous selection and education of the Guardians that he proposes could w…