Why the Communism did not survive, political economy theory

Capitalism survived because it was able of adopting radical measures taken from its ideological antagonism: Socialism; a contradiction itself.

It can not be denied that the New Deal of President Franklyn D. Roosevelt during the thirties and forties years of the twentieth century was a combination of liberal and socialism measures that promoted the intervention of the state in the most important social and economic activities of North America. This intervention of the state made possible for Capitalism to survive in this country. If you analyze each one of the policies of the New Deal you will verify that most of them were interventionist policies.

The intervention of the state was the vaccine that saved the Capitalism in the thirties and in the other crisis that this system has suffered since then. And what is a vaccine?

A vaccine is a product obtained from the same virus which eventually destroys.
Well, the Capitalism obtained the vaccine that saved itself from the virus of the Socialism, applying Socialist measures in the economy and in the society.

Orthodox Soviets leaders were not able to understand this reality and for that reason the Soviet Union collapsed in the eighties. If the Soviet leaders would had applied the same principle and had used Capitalism measures, perhaps the Soviet Union would had survived. But, on the contrary, they radicalized the Communism and the system could not resist. Chinese leaders understood this reality many years ago, and after Mao Tse Tung die in the seventies they applied a new method to guarantee the survival of their communist system. The Chinese leaders have applied the contradictory method that their Soviet colleagues were not able to accomplish. China is formally a Communist country but with liberal economic institutions open to the global economy and this has preserved the Chinese regime. How is this contradiction possible?

Theoretically it is not possible but in the reality it works. This demonstrates that sometimes there is a great difference between the theory and the reality.
The effect of this contradiction that occurs in the reality deserves to be deeply studied by politicians and economists worldwide.