告子下 · 第 10 / 16 章 · 孟子 6B.10
《孟子·告子下》6B.10：二十而取一，为什么仍可能是貉道
孟子指出，税率低并不自动等于好政治；若把有礼有人伦的中国秩序硬套成无城郭宗庙百官的貉国模式，就会用错误制度伤害真正的人伦结构。
白圭曰：「吾欲二十而取一，何如？」孟子曰：「子之道，貉道也。万室之国，一人陶，则可乎？」曰：「不可，器不足用也。」曰：「夫貉，五谷不生，惟黍生之，无城郭、宫室、宗庙、祭祀之礼，无诸侯币帛饔飧，无百官有司，故二十取一而足也。今居中国，去人伦，无君子，如之何其可也？陶以寡，且不可以为国，况无君子乎？欲轻之于尧舜之道者，大貉、小貉也；欲重之于尧舜之道者，大桀、小桀也。」
英文参考译文
Bai Gui said, 'I want to take a twentieth of the produce only as the tax. What do you think of it?' Mencius said, 'Your way would be that of the Mo. In a country of ten thousand families, would it do to have only one potter?' Gui replied, 'No. The vessels would not be enough to use.' Mencius went on, 'In Mo all the five kinds of grain are not grown; it only produces the millet. There are no fortified cities, no edifices, no ancestral temples, no ceremonies of sacrifice; there are no princes requiring presents and entertainments; there is no system of officers with their various subordinates. On these accounts a tax of one-twentieth of the produce is sufficient there. But now it is the Middle Kingdom that we live in. To banish the relationships of men, and have no superior men - how can such a state of things be thought of? With but few potters a kingdom cannot subsist; how much less can it subsist without men of a higher rank than others? If we wish to make the taxation lighter than the system of Yao and Shun, we shall just have a great Mo and a small Mo. If we wish to make it heavier, we shall just have the great Jie and the small Jie.'
重点修订页
人工补强的解释层
核心问题
为什么孟子反对把税减到二十取一还称之为善政？
直接回答
因为制度不能只看数字轻重，还要看它承载的是哪种社会结构。貉地可以二十取一，是因为它没有中国这套城郭、宗庙、百官、人伦秩序；若脱离结构只比税率，就会用看似轻省的方案拆掉真正需要维持的公共生活。
第一性原理
制度优劣不能脱离其所承载的整体结构来比较；脱离结构谈单一指标，常会把错误包装成优化。
为什么重要
这章适合承接“二十取一”“孟子 税制”“metrics without structure”这类搜索，是从第一性原理批评单指标改革的重要章句。
延伸阅读
这章在做什么
这章是《告子下》第 10 / 16 章，最直接的进入线索是“吾欲二十而取一，何如”。放回全卷，它讨论的是养心、判断与人格形成，并可与仁政互相印证。
更宽的搜索入口
如果你带着更宽的问题进入这一章，先从正确的 hub 页进入
全卷语境
《告子下》把养心、判断和人格形成连成一条修身路线。
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引用提示
不要把它读成反低税。孟子批评的不是税低本身，而是把不同文明结构的制度成本直接横向比较，进而误拆秩序。