We are simplifying a little, here. In their professional work, economists usually use a somewhat more professional criterion, the Pareto Optimum. A Pareto Optimum is defined as a situation in which it is not possible to make any one person better off without making someone else worse off. It turns out, though, that in order to have a Pareto Optimum we must maximize the net benefits. The common sense of it is that, if we can increase net benefits, we can give the increase in net benefits to somebody, make that person better off, and make nobody else better off -- so we do not have a Pareto Optimum unless we are maximizing net benefits. There is a bit more to the Pareto Optimum than that, be we will not go into any more detail here.