Changes

In his ''Manual of Political Economy'' (1906) the focus is on equilibrium in terms of solutions to individual problems of "objectives and constraints".  He used the indifference curve of Edgeworth (1881) extensively, for the theory of the consumer and, another great novelty, in his theory of the producer.  He gave the first presentation of the trade-off box now known as the "Edgeworth-Bowley" box.  

In his ''Manual of Political Economy'' (1906) the focus is on equilibrium in terms of solutions to individual problems of "objectives and constraints".  He used the indifference curve of Edgeworth (1881) extensively, for the theory of the consumer and, another great novelty, in his theory of the producer.  He gave the first presentation of the trade-off box now known as the "Edgeworth-Bowley" box.  

Pareto realized that cardinal utility could be dispensed with--that is, it was not necessary to know how much a person valued this or that, only that he preferred X of this to Y of that. Utility was a preference-ordering.  With this, Pareto not only inaugurated modern microeconomics, but he also demolished the alliance of economics and utilitarian philosophy (which calls for the greatest good for the greatest number; Pareto said "good" cannot be measured).  He replaced it with the notion of ''Pareto-optimality'', the idea that a system is enjoying maximum economic satisfaction when no one can be made better off without making someone else worse off.  Pareto optimality is widely used in welfare economics and game theory. A standard theorem is that a perfectly competitive markets create distributions of wealth that are Pareto optimal.

Pareto realized that cardinal utility could be dispensed with--that is, it was not necessary to know how much a person valued this or that, only that he preferred X of this to Y of that. Utility was a preference-ordering.  With this, Pareto not only inaugurated modern microeconomics, but he also demolished the alliance of economics and utilitarian philosophy (which calls for the greatest good for the greatest number; Pareto said "good" cannot be measured).  He replaced it with the notion of ''Pareto-optimality''. A system is Pareto-optimal when no one can be made better off without making someone else worse off.  Pareto optimality is widely used in welfare economics and game theory. A standard theorem, the first welfare theorem, states that under ideal conditions competitive markets create distributions of wealth that are Pareto optimal.