A just and ordered polity requires a rational, well ordered soul. Not all souls will achieve the rational ideal. This leaves the political voluntarist with a dilemma. Plato solved this by just putting the most just and ordered souls "in charge". But, of course, this is no solution at all, for the voluntarist.
The genius of Plato was both in recognizing the reality of these competing features of the human psyche, and in realizing that ultimately it is the rational portion that must stand apart from the horses and act as the ‘guardian’ of the entire self, rather than the hopelessly inadequate servant to the fractious elements, competing for its efforts. The genius of Orwell, whether he quite knew it or not, was in recognizing that modern man had surrendered responsibility for the charioteer by embracing men like Skinner and Freud, and that nothing good would ever come of it.