1) Well, a common man certainly can make a positive impact on society merely by accumulating and making use of the Virtues.
2) Common many have made positive impact accidentally on the world by virtuous action at the right moment in time. But that is not to say that they possessed a brilliant idea or persuasive character. It means only that as virtuous people they seized an opportunity when it came before them, even if they did not construct that opportunity themselves.
3) The historical record suggests that most people who make a significant POSITIVE impact on society are not average. In fact, the record is almost absent of common individuals. The people who do make a significant impact tend to be above average, largely from the middle or upper middle classes – in other words, not common.
4) The interesting question is whether the common man, correctly estimates that his reasons, opinions or imaginations, would produce what is a POSITIVE impact upon society. If you imagine what a child sounds like to an adult; what a student sounds like to a professor; what a common citizen sounds like to a statesman or scholar – the result is always the same: that we are always unconscious of our incompetence. If we were aware of our incompetence we might lack the will to do anything at all. So we evolved confidence in the face of ignorance out of necessity.
So the question is really whether the common man has any significant value to add to society other than his assumption that he does. On the other hand, there are many people who are not average who none the less are not omniscient, always looking for ideas to use in changing the world.
And so, it is possible that an ordinary fellow might stumble across a good idea. But even if he did, is it possible for his idea to compete with the many many ideas, of all the individuals who are above average, and who are ALSO struggling to change the world?
The market for ideas is no different from the market for products and services. If you cannot sell your idea, that is because no one is buying it. If no one buys it then that is evidence that it isn’t wanted. If it isn’t wanted, then by definition, it isn’t ‘good’.
The greeks had it right you know: wisdom is found in increasing the knowledge of your own ignorance.