Simon Bernhard Kochen is an American mathematician working in the fields of model theory, number theory and quantum mechanics. He has been a member of the Department of Mathematics at Princeton University since 1967. He was Chair of the department from 1989 to 1992 and was appointed Henry Burchard Fine Professor in Mathematics in 1994. In 1967, together with James Ax, he was awarded the Seventh Frank Nelson Cole Prize in Number Theory for three jointly written papers on Diophantine problems with regard to p-adic techniques. In the same year Kochen and Ernst Specker proved the Kochen-Specker theorem in quantum mechanics. This theorem is basic in determining certain scientific-philosophical positions in the interpretation and revision of principles governing Nature. In 2004 Kochen and John Horton Conway proved the free will theorem, which states that if we have a certain degree of free will, then subject to certain assumptions, so too must some elementary particles.