When environmentalists fail to persuade us that there is an imminent threat of environmental disaster, they typically invoke the "precautionary principle" in order to justify their calls for more regulation. This work challenges the claim that the precautionary principle (PP) is an appropriate guide to public policy decisions. The fundamental problem is that it is impossible to prove a negative, so the PP can be used to justify any regulation limiting emissions of any substance. Taken in its extreme form, the PP would end civilisation. In its more practical form, the PP is about taking a hyper-cautious approach to emissions of substances into the environment. This means imposing very strict controls on the licensing of new technologies and cutting back drastically on emissions of substances into the environment. Although not as devastating as Leggett's philosophically dubious proposal, this more practical approach has serious drawbacks The opening brace of papers discusses the dubious philosophical foundations of PP, and consider the consequences of applying it in various policy contexts relating to scientific controversies.

The root causes of land degradation are the actions of political entrepreneurs, aid agencies, and governments of developing countries who misuse 'aid' money. Only when individuals are permitted to own property, especially land and water, to engage in free trade, and to resolve disputes through customary law, will the problems of land degradation, poverty, and hunger be reduced to acceptable levels.