Proximate Vs. Root Cause
A proximate cause is the event most immediately responsible for an observed result, while a root (or ultimate) cause is the deeper, underlying reason it occurred. Distinguishing between the two is central to analysis in law, engineering, medicine, and biology.
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Origin
The legal distinction traces to Francis Bacon's 1596 Maxims of the Law: "in law, one looks to the near cause, not the remote one." In biology, Ernst Mayr formalized the proximate/ultimate distinction in his 1961 paper "Cause and Effect in Biology" in Science.
Updated February 22, 2026