What Protagoras meant by "man is the measure of all things"?
I would like to ask him: "Do you think that all ideas, notions and opinions are of equal value?"
For instance, some (in fact, few...) people think that states can find welfare better with a communist system, others believe that a capitalist ("free market") system is better. But historical experience showed that the latter opinion is better.
Did Protagoras mean that if I think that commumism is better, then this is true for me, if I think that capitalism is better then that is also true for me?
This is folly!