Conce has been raised about the ethics and risks of performing genetic interventions in macaque monkeys to study models of human neuropsychiatric conditions.Here I point out that, when the outcome of some situations is truly uncertain, human decision makers tend to evaluate these situations inconsistently.The consequences of this inconsistency are sometimes profound, as they lead policy makers and reviewers to ignore or discount the ethical costs of doing nothing.I conclude that there are fundamental problems with theprecautionary principle hat Weste policy makers often adopt to justify their decisions.