The One Divides into Two (一分为二) controversy was an ideological debate about the nature of contradiction that took place in China in 1964.^[1] The concept originated in Lenin's Philosophical Notebooks. The philosopher Yang Xianzhen originated the idea of "Two Unites into One", which he said was the primary law of dialectics. The Maoists interpreted this to mean that capitalism could be united with socialism. Ai Siqi wrote the original attack on Yang, and was joined by Mao himself. Wang Ruoshui also contributed to the attack. After 1976, Yang was officially rehabilitated, along with the concept of two uniting into one.^[2]

The chengyu phrase "一分为二" arose in the Taisu version of the Huangdi Neijing.

This phrase is derived from the formulation given by Vladimir Lenin in his Philosophical Notebooks; "The splitting of a single whole and the cognition of its contradictory parts ... is the essence ... of dialectics."^[3]

Richard Baum has put the controversy in terms of modern game theory as a debate between zero sum and non-zero sum competition. ^{[citation needed]}

Alain Badiou, during his Maoist phase, would use the principle of One Divides into Two to criticize the philosophy of Gilles Deleuze.^{[4][additional citation(s) needed]}

• Antagonistic contradiction
• On Contradiction