Population ethics is the philosophical study of the ethical problems concerning populations . It is also sometimes called population axiology , which is „the theory of the state of affairs is better than another, where the states of affairs may differ over the number of people who ever live „.  It is possible to affect individual persons but instead to replace one group of people with another. Such problems usually only arise when our actions affect future generations. Perspectives in population ethics include natalism(encouraging childbearing and population growth) and antinatalism (which sees birth as undesirable).
„Most discussion in population ethics has concentrated on how to evaluate populations in their goodness, that is, how to order populations by the relations“ is better than „and“ is as good as „. This field has been riddled with paradoxes, which are inconsistent in cases where the notion of people and their welfare varies. “ 
Population ethics is especially important when making large-scale decisions.  Population ethics can be applied to evaluate scenarios that influence how people value deaths in charitable organizations . 
Perspectives and methodology
One applied methodology includes using cost-effectiveness analysis to measure impact of intervention. These can be measured in QALYs (Quality-Adjusted Life Year) and / or DALYs (Disability-Adjusted Life Year) . QALYs is a measure of years lived assuming perfect health, while DALYs measure in years where perfect health is lost. The two terms originated in the 1970s and 1990s, and are internationally recognized units of measurement. Both measures may have limits in capturing 
- Average and total utilitarianism
- Mother’s paradox addition (also called the repugnant conclusion)
- Person-affecting view
- The Asymmetry (population ethics)
- Population Ethics, Aggregate Welfare, and the Repugnant Conclusion
- The Repugnant Conclusion in the Stanford Encyclopedia of Philosophy
- On the Buddhist Truths and the Paradoxes in Population Ethics
- Jump up^ Greaves, Hilary. „Comparing existence and nonexistence“. http://users.ox.ac.uk/~mert2255/talks/existence.pdf
- Jump up^ Arrhenius Gustav, 2004, The paradoxes of future generations and normative theory, The repugnant conclusion, essays on population ethics, p.201, Dordrecht, Holland: Kluwer Academic Publishers.
- Jump up^ Population Ethics: Theory and Practice. Future of Humanity Institute, University of Oxford. http://www.populationethics.org/
- Jump up^ Cotra, Ajeya (2016-12-12). „AMF and Population Ethics“ . The GiveWell Blog . Retrieved 2017-01-13 .
- Jump up^ EUFIC. „Measuring burden of disease – the concept of QALYs and DALYs (EUFIC)“ . www.eufic.org . Retrieved 2017-01-13 .