Online research in philosophy

Phil Dowe, in Physical Causation, addresses such questions as 'What are causal processes and interactions?', 'What is the connection between causes and effects?', and 'What distinguishes a cause from its effect?' Dowe not only provides explicit and original answers to these questions, but, en route, provides important critiques of alternative answers as well as sophisticated discussions of negative causation, the fork asymmetry, and quantum mechanics.

There is no question that the theory of quantum mechanics is empirically successful. What the formalism of the theory says about the world, however, remains controversial. In this class, we will look at different theories of quantum mechanics. We will examine a range of philosophical issues that arise for the different theories, including the measurement problem, non-locality, the ontological status of the wavefunction and configuration space, the nature of probability, causation, and the compatibility of quantum mechanics with relativity.

This is a clear and original account of causation based firmly in contemporary science. Dowe discusses in a systematic way an original, positive account of causation: the conserved quantities account of causal processes which he has been developing over the last ten years. The book describes causal processes and interactions in terms of conserved quantities: a causal process is the worldline of an object which possesses a conserved quantity, and a causal interaction involves the exchange of conserved quantities. Further, things that are properly called cause and effect are appropriately connected by a set of causal processes and interactions. The distinction between cause and effect is explained in terms of a new version of the fork theory: the direction of a certain kind of ordered pattern of events in the world. This particular version has the virtue that it allows for the possibility of backwards causation, and therefore time travel.

I apply some of the lessons from quantum theory, in particular from Bell’s theorem, to a debate on the foundations of decision theory and causation. By tracing a formal analogy between the basic assumptions of causal decision theory (CDT)—which was developed partly in response to Newcomb’s problem— and those of a local hidden variable theory in the context of quantum mechanics, I show that an agent who acts according to CDT and gives any nonzero credence to some possible causal interpretations underlying quantum phenomena should bet against quantum mechanics in some feasible game scenarios involving entangled systems, no matter what evidence they acquire. As a consequence, either the most accepted version of decision theory is wrong, or it provides a practical distinction, in terms of the prescribed behaviour of rational agents, between some metaphysical hypotheses regarding the causal structure underlying quantum mechanics.

Many physicists believe that time constitutes a serious problem in quantum mechanics. We show nevertheless that quantum mechanics does not involve a special problem for time, and that there is no fundamental asymmetry between space and time in quantum mechanics over and above the asymmetry that already exists in classical physics. The apparent problem of time arises when the time parameter is put on a par with dynamical position variables rather than with the coordinates of space. The commutation relations and uncertainty relations are generally considered to embody the essential content of elementary quantum mechanics, but the traditional mathematical expression of the uncertainty principle it shown to be quite unsatisfactory. It is the total energy that decrees whether or not the time variables of a system can be sharply determined.

Bohmian mechanics is an alternative interpretation of quantum mechanics. We outline the main characteristics of its non-relativistic formulation. Most notably it does provide a simple solution to the infamous measurement problem of quantum mechanics. Presumably the most common objection against Bohmian mechanics is based on its non-locality and its apparent conflict with relativity and quantum field theory. However, several models for a quantum field theoretical generalization do exist. We give a non-technical account of some of these models.

argues that the success of the backward causation hypothesis in quantum mechanics would provide strong support for a version of Reichenbach's account of the direction of causal processes, which takes the direction of causation to rest on the fork asymmetry. He also criticises my perspectival account of the direction of causation, which takes causal asymmetry to be a projection of our own temporal asymmetry as agents. In this reply I take issue with Dowe's argument at three main points: his claim that the backward causation hypothesis in QM is incompatible with my perspectival approach to the direction of causation; his defence of the fork asymmetry approach against a general criticism of mine based on the time-symmetry of microphysics; and his application of his preferred account of the direction of causal processes to the relevant cases in QM.

Can a present or future event bring about a past event? An answer to this question is demanded by many other interesting questions. Can anybody, even a god, do anything about what has already occurred? Should we plan for the past, as well as for the future? Can anybody precognise the future in a way quite different from normal prediction? Do the causal laws and the past jointly preclude free action? Does current physical theory entail a consistent version of backwards causation? Recent articles on the problem of backwards causation have drawn attention to the importance of the principle of the fixity of the past: that the past is now fixed. It can be shown that the standard argument against backwards causation (the bilking experiment) simply builds in the assumption of past fixity. A fixed past deprives future events of past efficacy. This has naturally led to the speculation that by abandoning past fixity real power over the past may be possible.In this paper I show that in order to have an interesting thesis of backwards causation it is not enough simply to drop past fixity. More must go. In particular, to ensure what could be called future-to-past efficacy we must abandon two entrenched principles of permanence: the principle of permanent fixity, and the principle of permanent truth. The only alternative for backwards causal theorists is to embrace real contradictions in nature.

In this paper, criticisms are made of the main tenets of Professor Mellor's argument against ‘backwards’ causation. He requires a closed causal chain of events if there is to be ‘backwards’ causation, but this condition is a metaphysical assumption which he cannot totally substantiate. Other objections to Mellor's argument concern his probabilistic analysis of causation, and the use to which he puts this analysis. In particular, his use of conditional probability inequality to establish the ‘direction’ of causation is shown to be in error. 1I am indebted to Drs H. Krips, L. O'Neill and to the anonymous referee for their suggestions and critical comments on earlier drafts.

Dummett and others have failed to show that an effect can precede its cause. Dummett claimed that 'backwards causation' is unproblematic in agentless worlds, and tried to show under what conditions it is rational to believe that even backwards agent-causation occurs. Relying on considerations originating in discussions of special relativity, I show that the latter conditions actually support the view that backwards agent-causation is impossible. I next show that in Dummett's agentless worlds explanation does not necessitate backwards causation. I then show why even relative backwards causation is impossible in his and Tooley's scenarios of parallel processes in which causes apparently act in opposite temporal directions. We thus have good reasons for thinking that backwards causation is impossible.