Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

The ethical basis of the null hypothesis


Further to T. Häusler's 'In Retrospect' review of Sinclair Lewis's 1925 novel Arrowsmith (Nature 453, 38; 2008), the book was required reading for graduate courses in professional practice and ethics in the biological sciences that I taught in the 1990s. Arrowsmith's ethical dilemma was whether he should deny some villagers his phage therapy so that they could serve as controls. His conundrum endures to this day — the choice between bequeathing knowledge from a properly designed controlled experiment and risking the health of members of the control group by withholding potentially beneficial treatment.

The control group provides an unbiased test of the null hypothesis, which predicts what to expect if our ideas of how nature works are wrong. It could be argued that it is therefore an ethical obligation for the scientist to take the null hypothesis seriously. No other professional is ethically obliged to consider what might happen if he or she is wrong.

Arrowsmith's employers put the entire ethical burden of choosing the control group and implementing the experiment onto his shoulders. Ethical burdens, however, are properly borne by the entire community. Current practices of having institutional review boards to oversee experiments, obtaining consent from the treated patient, double-blind procedures and full disclosure combine to ensure that the ethical burden of research is shared by all the people involved in the work and is not unfairly placed on a single individual.

Author information



Rights and permissions

Reprints and Permissions

About this article

Cite this article

Pastor, J. The ethical basis of the null hypothesis. Nature 453, 1177 (2008).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing