If you want to even talk about firms setting prices you have to talk about firms that have some ability to do so, and those are firms that have some market power: they are imperfectly competitive.
Is there any other method which can help us to resolve more effectively and efficiently the many problems which are menacing the foundations of Western society What is wrong with the alternative of Marxian economics as applied in the Socialist countries, which also harbor a plethora of unresolved problems Is the thinking of our time upside down, or are we using the wrong approach - both in the West and the East - and therefore cannot resolve the pending problems These are some of the leading questions to be answered during the rest of the twentieth century.
First, he broke the prevailing conventional wisdom of the past, i.e. the classical economics and method of reasoning, and brought for debate a new economic vision where government intervention becomes a part of and a major rule in the economic system. This was a new economic philosophy in contrast to the classical view where government intervention in a free society was conceived as an exception to the rule or not needed at all, according to the formula of laissez-faire or "hands-off policy".
Second, he wSecond, he was able to develop new tools of analysis like the multiplier theorem, the consumption function or the paradox of thrift - all devised to prove that his new economic philosophy based on the concept of active and permanent government intervention was necessary and workable.
Third, he was able to induce a large number of his peers in the economic profession to accept and follow his method of approach and the overall conceptualization, even though this was a sort of inverted type of analysis when compared with classical economics, as will be shown later.
The fact of the matter remains that his influence upon the thinking of his time was tremendous and unprecedented. Indeed, no other economist since Adam Smith enjoyed the opportunity to see that during his lifetime his ideas have conquered the world. This was a performance which raised Keynes to the status of the most influential economist of the twentieth century.
A new composite method of approach: equilibrium vs. disequilibrium
Classical economists were deficient in two major areas, one theoretical and the other practical. Their great performance was the study of stable equilibrium in theory where they found natural laws.
This direction culminated with the formulation of the Walrasian theorem of general equilibrium. However, they were deficient in not having studied with the same diligence and attention problems of disequilibrium which were closer to the existing economic and financial conditions of their time.
In other words, they were not aware of the existence of a gap between the harsh and unstable realities staring them in the face and the conceptual construction of an economics of stable equilib