Nomological

Nomological is an adjective meaning relating to laws, especially laws of nature or general laws that govern phenomena. In philosophy and science, the term characterizes the law-like nature of generalizations and explanations that appeal to such laws. The word comes from Greek nomos, law, and logos, study or reason, with English usage emerging in the 18th–19th centuries through Latin and French.

In philosophy of science, nomological generalizations are universal or highly supported statements that connect phenomena in a law-like way. They underpin explanations and predictions by offering regularities that extend beyond a single instance. The covering-law model of explanation, associated with Carl Hempel, treats an explanation as a deduction of the phenomenon from general laws together with initial conditions. A statement is described as nomological when it expresses a law-like relation rather than a merely accidental or contingent association.

Nomological statements are often contrasted with substantive causal explanations and with statistical generalizations. They involve laws of nature, such as conservation principles or Newtonian mechanics, and they imply a form of nomological necessity: if the laws are true, the phenomenon follows under appropriate conditions. However, not all necessary truths are considered nomological, since mathematical or logical necessities are typically regarded as non-nomological in this philosophical sense.

The term is most commonly used in philosophy of science and related disciplines, where it helps distinguish explanations and predictions that appeal to lawful regularities from those based on mere correlation or particular history.