Aspects of quantum non-locality - II: Superluminal causation and relativity

In a preceding paper, I studied the significance of Jarrett's and Shimony's analyses of 'factorisability' into 'parameter independence' and 'outcome i ndependence' for clarifying the nature of non-locality in quantum phenomena . I focused on four types of non-locality; superluminal signalling, action- at-a-distance, non-separability and holism. In this paper, I consider a fif th type of non-locality: superluminal causation according to 'logically wea k' concepts of causation, where causal dependence requires neither action n or signalling. I conclude by considering the compatibility of non-factorisa ble theories with relativity theory. In this connection, I pay special atte ntion to the difficulties that superluminal causation raises in relativisti c spacetime. My main findings in this paper are: first, parameter-dependent and outcome-dependent theories both involve superluminal causal connection s between outcomes and between settings and outcomes. Second, while relativ istic deterministic parameter-dependent theories seem impossible on pain of causal paradoxes, relativistic indeterministic parameter-dependent theorie s are not subjected to the same challenge. Third, current relativistic non- factorisable theories seem to have some rather unattractive characteristics . (C) 1998 Elsevier Science Ltd. All rights reserved.