John Bell showed that a big class of local hidden-variable models stands in conflict with quantum mechanics and experiment. Recently, there were suggestions that empirically adequate hidden-variable models might exist which presuppose a weaker notion of local causality. We will show that a Bell-type inequality can be derived also from these weaker assumptions. IntroductionThe EPR-Bohm experimentLocal causalityBell's inequality from separate common causes 4.1 A weak screening-off principle4.2 Perfect correlation and ‘determinism'4.3 A minimal theory for spins4.4 No conspiracyDiscussio
