Gao Zi I · Passage 02 / 20 · 孟子 6A.2
Mencius 6A.2: human nature is like water flowing downward
Gaozi argues that human nature is like water, which can be diverted east or west. Mencius replies that water may not distinguish east and west.
告子曰：「性，猶湍水也。決諸東方則東流，決諸西方則西流。人性之無分於善不善也，猶水之無分於東西也。」孟子曰：「水信無分於東西，無分於上下乎？人性之善也，猶水之就下也。人無有不善，水無有不下。今夫水：搏而躍之，可使過顙；激而行之，可使在山。是豈水之性哉？其勢則然也。人之可使為不善，其性亦猶是也。」
The philosopher Gao said, 'Man's nature is like water whirling round in a corner. Open a passage for it to the east, and it will flow to the east; open a passage for it to the west, and it will flow to the west. Man's nature is indifferent to good and evil, just as the water is indifferent to the east and west.' Mencius replied, 'Water indeed will flow indifferently to the east or west, but will it flow indifferently up or down? The tendency of man's nature to good is like the tendency of water to flow downwards. There are none but have this tendency to good, just as all water flows downwards. Now by striking water and causing it to leap up, you may make it go over your forehead, and, by damming and leading it you may force it up a hill - but are such movements according to the nature of water? It is the force applied which causes them. When men are made to do what is not good, their nature is dealt with in this way.'
Priority note
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Central question
Why does Mencius answer Gaozi by asking whether water distinguishes only east and west, but not up and down?
Direct answer
Because he is distinguishing two questions: what can be redirected by force, and what its underlying tendency is. Water may be diverted east or west, but it still tends downward. Human beings are also pulled by circumstance without therefore being neutral at the root about good and bad.
First principle
To judge a thing's nature, one must ask not only how it can be distorted, but where it naturally goes once distortion is removed.
Why it matters
This passage strongly serves searches around human nature, the water analogy, Gaozi, and why Mencius still maintains the goodness of human nature.
Further reading
What this passage is doing
This is passage 2 of 20 in Gao Zi I. The cleanest entry point is "Man's nature is like water whirling round in…". In context, it works as part of Mencius's argument about human goodness, desire, and the debates with Gaozi and can be read alongside Human nature, Humane government / kingly way.
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Related principles
Citation note
Do not read it as denial of environmental influence. Mencius fully grants that water can be splashed upward and people can be bent by conditions. His point is that distortion does not define the root tendency.