Finance and Economics；Free exchange;Zero-sum debate;
财经；自由兑换; 零和争论;
Economists are rethinking the view that capital should not be taxed;
经济学家正重新考虑是否要推翻不该对资本征税的观点。
EXECUTIVES thunder that America's corporate-tax rates are to blame for economic weakness. Mitt Romney's campaign accuses Barack Obama of waging a “war on capital”. In fact, America's taxation of capital is more murky than confiscatory. At 39.2% (including state and local tax) its top corporate rate is the rich world's highest but loopholes mean most companies end up paying 27.6%, similar to Britain's effective rate of 27.4% and below Germany's 31.6%. America's tax rate on capital gains, at 15%, is lower than in many other countries. And if Mr Romney is the more ardent defender of capital, both men agree on the need for reforms. This is less a battle, more a skirmish.
行政当局愤怒指出美国经济疲软应归咎于公司企业所得税率。米特·罗姆尼发起一场运动指责奥巴马掀起了“对资本的战争”。事实上，美国的资本税与其用于没收充公，不如说其使用含混不明。其最高企业所得税税率高达39.2%（包括州政府和当地政府所征税收），居发达国家之首，不过由于存在漏洞，大多数公司最终支付的税率为27.6%，接近于英国的实际税率27.4%，低于德国的实际税率31.6%。美国的资本利得税税率为15%，比很多国家都要低。尽管罗姆尼更热衷于维护资本，他和奥巴马都认为有必要进行改革。这不像一场战争，反而只是一场小争论罢了。

The more interesting fight is going on within economics. For a generation, the profession's message on capital taxes has been simple: the lower the better. Most economists would prefer no tax on capital income at all. This seeming fanaticism is rooted in sensible models, developed in the 1970s and 1980s and built on a pleasing simplicity. Taxation inevitably involves trade-offs. Governments tax in order to fund public goods and limit inequality, but taxes are no free lunch. People and businesses respond—a tax on carrots, say, reduces carrot consumption—and these responses distort the economy and may reduce its potential growth rate.
经济学内部发生了更有趣的争执。一代以来，经济学家对于资本税的看法十分简单：税率越低越好。大多数经济学家根本不支持对资本收入征税。这种表面上的狂热植根于一些实用模型，它们于20世纪70年代到80年代发展起来，其基本特征是简洁，因此令人愉悦。税收不可避免地涉及了交换。政府征税是为了提供公共产品和限制收入不公，然而税收并非免费的午餐。个人和企业会提供反响，例如，对胡萝卜征税会减少胡萝卜的消费量，而这些反应使得经济扭曲，并有可能减少经济的潜在增长率。

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