Although it's attributed to him, William of Ockham did not come up with Occam's Razor. My metaphysics teacher showed me a line in the Summa Contra Gentiles whe

Although it's attributed to him, William of Ockham did not come up with Occam's Razor. My metaphysics teacher showed me a line in the Summa Contra Gentiles where St. Thomas Aquinas enunciated the same idea behind the Razor almost a hundred years before Ockham did. Sorry, I don't have the reference handy. Furthermore, the Wikipedia article on Ockham's Razor traces the basic idea all the way back to Aristotle's Posterior Analytics.