Occam’s Razor

History of Occam’s Razor

William of Ockham (also spelled Occam) was a Franciscan theologian born in Surrey, England, around 1285. He studied at Oxford and later at Paris. His philosophical views made him a polemic scholar. He died in Munich, Germany, around 1349.

Although the general idea of the preference for simplicity is attributed to William of Ockham, there are some precedents. Some writings by Duns Scoto, Ockham’s teacher, mention similar principles. A french Dominican named Durand de Saint-Pourcain used this idea before. Even earlier, Aristotle made statements such as “nature operates in the shortest way possible”, “the more limited, if adequate, is always preferable”, and “if the consequences are the same it is always better to assume the more limited antecedent”.

In the history of Science we find the principle has often been cited to argue in favor of one theory over others. It has played an especially successful role in physics. One example is the preference for Newton’s laws of motion and gravitation over Kepler’s laws of planetary motion. Although both theories made essentially the same predictions about the motions of the planets, Newton’s law is simpler and more general, requiring fewer assumptions, and was hence preferred. Newton’s theory was later empirically confirmed when its predictions led to the discovery of the planet Neptune.

An earlier application of Occam’s Razor, also in astronomy, was the controversy between heliocentric and geocentric models of the solar system. Ptolemy explained the observed movement of the stars using a rather complex model with the Earth in the center, and the planets orbiting around invisible spheres which themselves were orbiting around the Earth. Aristarco of Samos in Greece, and later Copernicus, convincingly argued for a simpler model in which the sun is in the center and the planets orbit around it.