William of Ockham, c. 1287 - 1347, was an English Franciscan Friar, scholastic philosopher and theologian. William of Ockham was a great scientific thinker of the 14th century. To Ockham, science was a matter of discovery.
One important contribution that he made to modern science and modern intellectual culture was efficient reasoning with the principle of parsimony in explanation and theory building that came to be known as Ockham's Razor. This maxim states that one should always opt for an explanation in terms of the fewest possible causes, factors, or variables. The principle says that one should not multiply entities beyond necessity - Entia non sunt multiplicanda sine necessitate. Among competing hypotheses, the hypothesis with the fewest assumptions should be selected.