In this paper I wish to examine the claim that it would be possible for us now to do something which would be the posterior efficient cause of some past event. I am not prepared to discuss the physics of elementary particles, and I will not consider what is sometimes called time reversal. Rather my analysis will be limited to cases in which it is alleged that we, in a world of middle-sized physical objects where most causes precede or are (...) simultaneous with their effects, could conceivably do something so that something else should have happened. I will argue that some of the cases which meet this description are indeed backwards causation if one is prepared to make certain assumptions about time. I will not evaluate these assumptions; rather I will try to clarify them and to make plain their implications for causality. For the argument about backwards causation is most fundamentally, or so I will try to show, an argument about the nature of time. (shrink)

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. (shrink)

Tarski's equivalence, as he allows, applies only roughly to assertions in ordinary language. Some of the relevant exceptions are of merely grammatical importance but others leave scope for interesting metaphysical pronouncements on science, mathematics and other fields of assertion. To understand these latter exceptions is to gain insight into Baylis' and Lukasiewicz' views on the question "Are some Propositions neither True nor False?" (this journal, 1936). From different standpoints each is right and each is wrong. This comment also applies to (...) some later contributions to their controversy. (shrink)