Keynesian economics is a horrible system, but so far it works the best until we have another implemented
Keynesian economics is not science, it's just form of propaganda. You receive money from government to justify big government and call this economics, ecology etc.
So you mean the Keynesian economics is not exactly as what they said because they're under control of the goverment?
Although inflation and deflation are different for different countries, yet it is now always within control of the government. Government can only plan and solve the problems for long terms. For example, inflation depends on the international rates, facts and figures.
On the other hand, supply and demand can be affected by unequal supply and demand. So, its generally a phase that every person has to go through.