Final answer:
Marx's theory of communism had flaws such as underestimating the complexities of forming a classless and affluent society, assuming uniform conditions for the rise of socialism, and failing to predict the centralization of power in authoritarian regimes. Divergence between theory and practice led to the struggles and decline of communist nations.
Step-by-step explanation:
When evaluating Karl Marx's theory in the context of why communist nations have not survived or are currently struggling, several flaws stand out. Marx underestimated the complexities of forming a society that is simultaneously affluent and classless. He envisioned that as economies advanced, capitalism would create conditions ripe for a proletarian revolution, leading to the development of communism. However, Marx did not adequately detail when the material conditions for a socialist revolution were ripe, nor could he predict the unique paths that different nations would take toward industrialization.
Further, the Marxist theory required a centralization of power which, especially in Eastern Europe, proved difficult to dissolve among authoritarian regimes. The belief in a class struggle as the root of historical conflict didn't account for the political realities and variations in industrial progression across countries. Additionally, Marx's predictions did not match with the unfolding events; revolutions occurred in less industrialized nations like Russia, and the expected workers' solidarity sometimes gave way to other ideologies, like fascism.
In essence, the practical application of Marxist theory did not align with the anticipated outcomes. Nations that adopted communism faced challenges from limited industrialization, extreme authoritarian control, and resistance to relinquishing centralized power, which ultimately undermined the equitable society Marx envisaged. The discrepancies between theory and practice in Marxism contributed to the struggles and eventual decline of communist nations throughout the 20th century and into the present.