人之性惡其善者偽也
Human Nature Is Bad; What Is Good Is Artificial
人之性惡，其善者偽也。今人之性，生而有好利焉，順是，故爭奪生而辭讓亡焉；生而有疾惡焉，順是，故殘賊生而忠信亡焉；生而有耳目之欲，有好聲色焉，順是，故淫亂生而禮義文理亡焉。然則從人之性，順人之情，必出於爭奪，合於犯分亂理，而歸於暴。故必將有師法之化，禮義之道，然後出於辭讓，合於文理，而歸於治。用此觀之，人之性惡明矣，其善者偽也。
Human nature is bad; what is good in people is artificial. Now human nature at birth includes a fondness for profit — follow this, and contention and robbery arise while deference and yielding vanish. It includes envy and hatred — follow this, and violence and crime arise while loyalty and trustworthiness vanish. It includes the desires of the ears and eyes, a fondness for beautiful sights and sounds — follow this, and licentiousness and disorder arise while ritual propriety, duty, and civilized patterns vanish. Therefore to follow human nature and comply with human feelings will inevitably lead to contention and robbery, accord with the violation of social divisions and the disruption of natural order, and culminate in violence. There must be the transforming influence of teachers and standards, the guidance of ritual propriety and duty — only then will deference and yielding emerge, accord with civilized patterns, and culminate in good order. Viewed in this light, it is clear that human nature is bad, and what is good is artificial.
Notes
This is Xunzi's most famous and controversial chapter. His term 偽 (wěi, 'artificial/deliberate') does not mean 'false' but rather 'produced through conscious effort' — contrasted with 性 (xìng, 'nature'), which is what one is born with. For Xunzi, all moral goodness is the product of education, ritual training, and deliberate cultivation, not innate endowment. This directly opposes Mencius's doctrine that human nature is good.