Marginalism advocates using mathematics to tackle economic problems. This book points out that marginalist mathematics is incomplete, and thus leads to various suspicious, paradoxical, and wrong theories. For example, it claims that raising marginal productivity increases profit, that marginal cost pricing is Pareto optimal and an effective policy to regulate monopoly, that lazier workers should get higher pay, that population should be killed to raise economic growth, and that punishment can reduce crime or pollution, etc. This book then singles out the culprits of this wrong mathematics, kills many marginal concepts, and provides the correct substitutes.