What do the authors of NSC-68 identify as most contagious idea in history?

NSC-68, a top-secret policy paper written in 1950, does not explicitly identify a single "most contagious idea in history." However, it does discuss the threat posed by the "Communist ideology" as being highly contagious.

The document argues that the Soviet Union, through its ideology, is actively trying to expand its influence and overthrow existing governments. This is seen as a global threat that requires a strong US response to contain it.

The paper highlights the contagious nature of communist ideas due to their appeal to:

* Economic grievances: Communism offered an alternative to capitalist systems that were perceived as exploitative.

* Social injustices: It promised a society where everyone is equal and has access to basic needs.

* Nationalism: It appealed to countries struggling for independence or seeking to throw off colonial rule.

NSC-68, while focusing on the threat of communism, indirectly hints at the potential for any powerful ideology to spread rapidly and influence global events. The document underscores the importance of understanding and countering the spread of such ideas, which it sees as a threat to the existing world order.