The One Divides into Two controversy (一分为二) was an ideological debate about the nature of contradiction that took place in China in 1964. 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 the Aesopian meaning of this to be 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 rehabilitated as well as the concept of two uniting into one.
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.”