Ockham (Occam), William of (c. 1280–1347)
William of Ockham was a 14th century intellectual, known for the principle called Ockham's razor ("Entities must not be unnecessarily multiplied"), who joined the Franciscan order and studied at Oxford, where he was a contemporary of Jean Buridan, and Paris. He went further than Buridan in modifying Aristotle's doctrine of natural place by arguing that the elements in each world would return to their natural place within their own world, without any intervention by God. Although he began by supporting pluralism, he later became a strong opponent of the idea, citing the view that neither other worlds nor the creation of man elsewhere were mentioned in the Scriptures.
"When you have two competing theories that make exactly the same predictions, the simpler one is the better". This is the principle of parsimony, the axiom that it is pointless to achieve with more than what can be done with less, or the principle of plurality, that many hypotheses should be posited on;y when absolutely necessary. The idea that the simplest explanation is usually the correct explanation has always been the guiding principle whenever humanity has been faced with a choice, problem, or dilemma. We know a dog barks because we hear it. We know a grapefruit is sour because we can taste it. That principle of Ockham's (or Occam's razor).
Ockham's razor gives precedence to the notion of simplicity and holds that simplicity is equal to perfection. Although it's named after William of Ockham, there's no evidence he ever used the phrase in any of his extensive writings, despite being clearly predisposed to the concept.
In fact, the principle of Ockham's razor was recognized long before Ockham's time, not least in ancient Greece. Aristotle wrote, "The more perfect a nature is, the fewer means it requires for its operation". The principle remained significant. Austrian physicist Ernst Mach (1838–1916), who studied the mechanics of projectiles moving at supersonic speeds, said that scientists should use the simplest methods possible in their research. Now, the principle that one should never make more assumptions that are absolutely required underlies all scientific and theoretical modeling. It helps to change off variables that muddy the waters of inquiry and threaten to introduce ambiguities and inconsistencies. Ockham's razor has become part of science's everyday intellectual furniture, its most basic of tools.