In this chapter (Paul Horwich, “Time Travel” in Asymmetries in Time: Problems in the Philosophy of Science (Cambridge, MA: The MIT Press, 1987), 111-128.) Horwich discusses Gödelian time travel. He defends Gödel’s claim against the objection that time travel, as he envisions it, cannot occur since it would engender anomalous consequences. He then briefly deals with arguments for a Gödelian spacetime, which entails a closed universe and closed timelines. He then defends issues about anomalous changes and bilking arguments dealing with backwards causation. He concludes his arguments with a defense of Gödel’s thesis that there is a real possibility of trips to the spatially distant past (128).
Horwich dismisses things way too easily. When discussing objections to known physical features of the universe he appeals to mathematical models that make it theoretically possible. Theoretically, time travel is less abrasive but it being physically possible is another thing. Horwich does discuss the feasibility of obtaining such treks but treads lightly on their objections. It would have been beneficial to discuss feasibility objections in more depth such as the need to harness enough energy to have spacetime move through the object rather than the object through spacetime.
- If time travel were possible, then X would be possible.
- But X is impossible.
- Therefore, time travel is impossible.
The improbability of bilking attempts gives no reason to suspect that spacetime is non-Gödelian .
- If spacetime permits time travel, then men will travel into their local past.
- If men will travel into their local past, then there will be bilking attempts.
- Any such bilking attempts will be thwarted.
- The regular thwarting of bilking attempts will not involve an endless string of improbable coincidences.
- Therefore, if spacetime permits time travel, the there would occur certain phenomena that we have empirical reasons to believe will not in fact occur.
- Therefore, Spacetime does not permit time travel.
The argument must assume a lot of different physics and metaphysics. In order for Gödel’s argument to work spacetime must be cylindrical and time must be circular. Horwich’s arguments allowing for the possibility of Gödelian time travel seemed rather weak. Gödel’s model requires a closed universe, which observationally does not seem to be the case. 2) Backwards causation seem, to me, incoherent. To allow for AàB but yet BàA follows it does not make sense to then say that in order to achieve BàA if A is needed for B to begin with (bilking/autofanticide). This requires special pleading and ad hoc conjecture, especially if ‘coincidences’ are to occur. 3) I think [Gödelian] backwards time travel can be ruled out inductively since it should be the case that we see anomalies occurring.