Causarum Investigatio and the Two Bell's Theorems of John Bell

Understand

"Bell's theorem" can refer to two different theorems that John Bell proved, the first in 1964 and the second in 1976.

• His 1964 theorem is the incompatibility of quantum phenomena with the joint assumptions of Locality and Predetermination.
• His 1976 theorem is their incompatibility with the single property of Local Causality.
• This is contrary to Bell's own later assertions, that his 1964 theorem began with the assumption of Local Causality, even if not by that name.