Some economics problems
I am confused about pareto efficiency which means when someone in the society become better off, another must become worse off.
in my book I see that perfectly competitive market is pareto efficiency. But, I think both consumers and seller benefit from their transaction- I mean both of them become better off, a opinion that contradicts from the definition of pareto efficiency.
thus, I need someone who can explain this paradox( maybe I am wrong to understand this concept)
BTW, in my book I see that if marginal social benefit=marginal private benefit + the value of externality, the whole society is pareto efficiency, I cannot figure out this point, so I need your help