Scientific Law - Introduction

Introduction

A scientific law or scientific principle is a concise verbal or mathematical statement of a relation that expresses a fundamental principle of science, like Newton's law of universal gravitation. A scientific law must always apply under the same conditions, and implies a causal relationship between its elements. The law must be confirmed and broadly agreed upon through the process of inductive reasoning. As well, factual and well-confirmed statements like "Mercury is liquid at standard temperature and pressure" are considered to be too specific to qualify as scientific laws. A central problem in the philosophy of science, going back to David Hume, is that of distinguishing scientific laws from principles that arise merely accidentally because of the constant conjunction of one thing and another.

A law differs from a scientific theory in that it does not posit a mechanism or explanation of phenomena: it is merely a distillation of the results of repeated observation. As such, a law is limited in applicability to circumstances resembling those already observed, and is often found to be false when extrapolated. Ohm's law only applies to constant currents, Newton's law of universal gravitation only applies in weak gravitational fields, the early laws of aerodynamics such as Bernoulli's principle do not apply in case of compressible flow such as occurs in transonic and supersonic flight, Hooke's law only applies to strain below the elastic limit, etc.