From Bertrand Russell's History of Western Philosophy, p 106:
Two general questions arise in confronting Plato with modern ideas. The first is: Is there such a thing as "wisdom" ? The second is : Granted that there is such a thing, can any constitution be devised that will give it political power?
"Wisdom," in the sense supposed, would not be any kind of specialized skill, such as is possessed by the shoemaker or the physician or the military tactician. It must be something more generalized than this, since its possession is supposed to make a man capable of governing wisely. I think Plato would have said that it consists in knowledge of the good, and would have supplemented this definition with the Socratic doctrine that no man sins wittingly, from which it follows that whoever knows what is good does what is right. To us, such a view seems remote from reality. We should more naturally say that there are divergent interests, and that the statesman should arrive at the best possible compromise.The members of a class or a nation may have a common interest, but it will usually conflict with the interests of other classes or nations. There are, no doubt, some interests of mankind as a whole, but they do not suffice to determine political action. Perhaps they will do so at some future date, but certainly not so long as there are many sovereign States. And even then the most difficult part of the pursuit of the general interest would consist in arriving at compromises among mutually hostile special interests.
But even if we suppose that there is such a thing as "wisdom," is there any form of constitution which will give the government to the wise? It is clear that majorities, like general councils, may err, and in fact have erred. Aristocracies are not always wise; kings are often foolish; Popes, in spite of infallibility, have committed grievous errors. Would anyone advocate entrusting the government to university graduates, or even doctors of divinity? Or to men who, having been born poor, have made great fortunes? It is clear that no legally definable selection of citizens is likely to be wiser, in practice, than the whole body.
It might be suggested that men could be given political wisdom by a suitable training. But the question would arise: what is a suitable training? And this would turn out to be a party question.
The problem of finding a collection of the "wise" men and leaving the government to them is thus an insoluble one. That is the ultimate reason for democracy.
So the Representatives are not superior governors than any other set of citizens would be. We could, and should, all 200 million voting age citizens, do at least as good a job as any set of lawmakers would. And, that is the ultimate reason for Actual Democracy: we vote on the laws. Our power as citizens remains "our power as citizens". Nothing complicated. No way to get crossed up. Just responsible people doing their civic duty and carrying out their legislative responsibilities.