This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Mencius's claim that human nature is good, xing shan, sounds at first like an empirical claim about how people actually behave, and read that way it seems obviously false. Cruelty, cowardice and self-interest are common enough in the fourth century BCE world Mencius traveled, arguing state to state, as much as in any other era. But the Stanford Encyclopedia's account of the Mengzi, following the sinologist A.C. Graham, shows that Mencius was making a more careful claim than the flat English translation suggests. For Mencius, a thing's nature is what it will become when its growth is not stunted or interfered with, the way an orange seed's nature is to bear fruit even though most orange seeds never do, and the way human speech is part of human nature even though infants cannot yet speak. To say human nature is good is to say that under the right conditions, people tend toward benevolence, righteousness, wisdom and propriety, not that people already possess these virtues in finished form.
The clearest statement of the position comes in a debate recorded at Mengzi 6A6, where Mencius rejects three alternatives he attributes to rival views: that nature is neither good nor bad, that it can become either, or that some natures are good and others are not. His answer turns on four feelings he says everyone has, compassion, disdain for dishonor, respect and the capacity to approve or disapprove, which he identifies directly with the four cardinal virtues. Famously he illustrates the first of these with the case of a person who sees a child about to fall into a well: the alarm and compassion that arise are immediate, prior to any calculation of reputation or reward, and for Mencius that reflex is proof that compassion belongs to human nature rather than being imposed on it from outside.
But the position raises an obvious problem that Mencius has to answer in his own text: if the four sprouts are universal, why do people turn out so differently, some becoming, in his words, great and others petty. His answer, given to the disciple Gongduzi at 6A15, locates the difference not in unequal endowment but in unequal reflection. The senses, eyes and ears, respond automatically to attractive things and can pull a person along without any exercise of judgment, while the heart is the one organ whose function is to reflect, and reflection is the only thing that reliably recovers the sprouts before the senses crowd them out. A person becomes bad, on this account, not because the sprouts were never there but because they went uncultivated, misdirected by things rather than governed by the heart's own activity.
The entry also flags a smaller but telling scholarly correction. The Chinese phrase most commonly used to summarize Mencius's teaching in later centuries, benshan, meaning fundamentally good, does not actually occur in the Mengzi. It was supplied by the Song dynasty commentator Zhu Xi, who read Mencius through a metaphysical distinction between an underlying and a manifested nature that the original text does not draw. Zhu Xi's gloss became so authoritative, memorized for a thousand years of civil service examinations, that it is easy to mistake it for Mencius's own words. The dispute matters because it is really two disputes at once, a philosophical one about what moral development requires and a philological one about how much of what we call Mencius's view was written by Mencius at all, and separating them is most of the work of reading him accurately.