Note: Do not rely on this information. It is very old.
OckhamOckham, or Occam, William of, the name, derived from his birthplace in Surrey, by which one of the leading Schoolmen is known. In 1322 he joined in the revolt against Pope John XXII. and, after a brief imprisonment, escaped to Munich. Ockham was a Nominalist, and in his Summa Logices demolished Realism. He is best known popularly for the maxim (closely allied to Newton's First Rule of Philosophising), "Entia non sunt multiplicanda praeter necessitatem." He also insisted on the rights of secular princes as against the Papacy. He is often styled Doctor Singularis or Invincibilis. He probably died in 1349.
Click for more about XXII