Ockham's razor (also spelled Occam's razor, pronounced AHK-uhmz RAY-zuhr) is the idea that, in trying to understand something, getting unnecessary information out of the way is the fastest way to the truth or to the best explanation. William of Ockham (1285-1349), English theologian and philosopher, spent his life developing a philosophy that reconciled religious belief with demonstratable, generally experienced truth, mainly by separating the two. Where earlier philosophers attempted to justify God's existence with rational proof, Ockham declared religious belief to be incapable of such proof and a matter of faith. He rejected the notions preserved from Classical times of the independent existence of qualities such as truth, hardness, and durability and said these ideas had value only as descriptions of particular objects and were really characteristics of human cognition.
Ockham was noted for his insistence on paying close attention to language as a tool for thinking and on observation as a tool for testing reality. His thinking and writing is considered to have laid the groundwork for modern scientific inquiry.
Ockham's insistence on the use of parsimony (we might call it minimalism) in thought resulted in some later writer's invention of the term, Ockham's razor. Among his statements (translated from his Latin) are: "Plurality is not to be assumed without necessity" and "What can be done with fewer [assumptions] is done in vain with more." One consequence of this methodology is the idea that the simplest or most obvious explanation of several competing ones is the one that should be preferred until it is proven wrong.