For many centuries, conquest was commonplace, and its attractiveness was central to the character of international politics. Why has it declined? Existing theories cannot explain why powerful countries no longer conquer states with easily extractable wealth. We develop an explanation based on the relationship between a potential conqueror's economic productivity and its ability to profit from conquest. Productivity has opposing effects on conquest's profitability: it raises the opportunity cost of each asset diverted to conquest, but also reduces the quantity of assets required for conquest. The net effect is determined by the composition of investment in innovation. We document that since at least 1950 investment has been predominantly aimed at civilian, not military innovations, so that rising productivity should reduce conquest's net profitability. Using cost analyses of comparable wars, we estimate bounds on the profitability of conquering the oil and gas reserves of the Persian Gulf, a very tempting target, for the United States and Iraq, two potential conquerors of widely differing productivity. Though both mechanisms operate, we find that the net effect of higher productivity is to reduce the profits from conquest. Moreover, this net effect is large enough to render conquest generally unprofitable for contemporary high-productivity states.

中文翻译：

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粗略计算：生产力和征服的盈利能力

许多世纪以来，征服是司空见惯的，它的吸引力是国际政治特征的核心。为什么下降了？现有的理论无法解释为什么强国不再征服财富容易获取的国家。我们根据潜在征服者的经济生产力与其从征服中获利的能力之间的关系来进行解释。生产力对征服的盈利能力有相反的影响：它提高了被转移到征服的每项资产的机会成本，但也减少了征服所需的资产数量。净效应取决于创新投资的构成。我们记录了至少自 1950 年以来，投资主要针对民用，而不是军事创新，因此生产力的提高应该会减少征服” 的净盈利能力。通过对可比战争的成本分析，我们估计了征服波斯湾石油和天然气储量的盈利能力，这对美国和伊拉克来说是一个非常诱人的目标，这两个潜在的征服者生产力差异很大。尽管这两种机制都起作用，但我们发现更高的生产力的净效应是减少征服的利润。此外，这种净效应大到足以使征服对当代高生产力国家普遍无利可图。我们发现更高的生产力的净效应是减少征服的利润。此外，这种净效应大到足以使征服对当代高生产力国家普遍无利可图。我们发现更高的生产力的净效应是减少征服的利润。此外，这种净效应大到足以使征服对当代高生产力国家普遍无利可图。