At FMER I had an opportunity to chat with Michael Tooley about time travel. Two years ago I had this paper about Tooley's example of loopless time travels and conditional logics. Michael put forward this example to indicate that if Lewis-Stalnaker semantics for conditional logics is adequate, then there are impossible cases of backward causation even without causal loops. Later on the argument was interpreted as an argument against the adequacy of conditional logics from the possibility of time travel (I recall that seemed to be the interpretation of Charles Cross, I was commenting on his talk at WCPA 2006 in Vancouver).
My point was that the impossibility of the situation described not only follows from basic assumptions of LS semantics, not only can be proven syntactically as holding in many conditional logics (that was Charles' observation), but also can be proven using fairly weak assumptions, weaker that those of Charles, and that the possibility of the situation is not very intuitive to start with (thus I rather sided with Michael, emphasizing that even without causal loops time travel can be tricky).
The chat reminded me about this paper, so I dug it up and posted to my academia profile. It's here.
My point was that the impossibility of the situation described not only follows from basic assumptions of LS semantics, not only can be proven syntactically as holding in many conditional logics (that was Charles' observation), but also can be proven using fairly weak assumptions, weaker that those of Charles, and that the possibility of the situation is not very intuitive to start with (thus I rather sided with Michael, emphasizing that even without causal loops time travel can be tricky).
The chat reminded me about this paper, so I dug it up and posted to my academia profile. It's here.
Comments