c.1285 - 1349
William of Occam was the last of the great scholastics, and Chief founder of Nominalism, that is, the separation of logic from faith.
Occam was a Franciscan especially trained in logic. He came into conflict with the pope over the strictness of Franciscan poverty.
Occam is best known for what is called 'Occam's razor' which states that 'Entities are not to be multiplied without necessity', or 'It is vain to do with more what can be done with fewer'. That is to say, if everything in some science can be interpreted without assuming a complicated hypothesis, there is no ground for assuming the complicated version.
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From the Internet Encyclopedia of Philosophy
From the Catholic Encyclopedia: