The Asymmetry is a view in population ethics stating that creating bad lives is morally bad, but creating good lives is not morally good. That is, there is an asymmetry between (i) the strong moral reason to avoid creating lives filled with suffering and (ii) the absence (or weakness) of a corresponding reason to create happy lives.

This asymmetry is often used to support views such as anti-natalism, the rejection of total utilitarianism, and suffering-focused ethics. Proponents argue that suffering is intrinsically bad and worth preventing, while the absence of happiness, when no one exists to miss it, is not a problem. The view is often contrasted with symmetric population axiologies that treat happiness and suffering as equally morally weighty.

Critics, including MacAskill, have argued that if it is bad to bring a suffering life into existence, then symmetry suggests it should be good to bring a happy life into existence. Others point out that real-world intuitions and survey data often show strong asymmetries in how people value creating happiness versus preventing suffering. Some argue this supports asymmetric views empirically.

Asymmetric views also interact with questions about moral uncertainty, extinction risk, and the value of future generations. For instance, if we give weight to asymmetric theories under moral uncertainty, we may be less inclined to see population expansion or extinction risk reduction as clear moral imperatives.