time travel horwich’s reply

lewisian time travel Eternalism The B-Theory The 4D view

lewisian time travel One cannot change the past. One can commit grampatricide. One can commit retrosuicide. (?)

the bilking argument 1. If spacetime permits time travel, then men will travel into their local pasts. 2. If men will travel into their local pasts, then there will be bilking attempts. 3. Any such bilking attempt will be thwarted. 4. The regular thwarting of bilking attempts will involve an endless string of improbable coincidences. 5. If spacetime permits time travel, then there would occur certain phenomena that we have empirical reasons to believe will not in fact occur. 6. [So] Spacetime does not permit time travel.

the revised bilking argument 1. If time travel into the local past by people with the intention to change the past becomes common, then banana peel slips, last minute changes of heart, etc. will become common. 2. It is not the case that banana peel slips, last minute changes of heart, etc. will become common. 3. [So] Time travel into the local past by people with the intention to change the past will not become common.

inductive arguments 1. All observed ravens have been black. 2. [So] All ravens are black.

inductive arguments 1. Most observed raven have been black. 2. [So] Most ravens are black.

inductive arguments 1. Non-black ravens have been uncommon in the observed cases. 2. [So] Non-black ravens will not become common in the future.

inductive arguments 1. Banana peel slips, last minute changes of heart, etc. have been uncommon in the observed cases. 2. [So] Banana peel slips, last minute changes of heart, etc., will not become common in the future.

arguments by analogy 1. All observed ravens have been black. 2. [So] All ravens are black.

arguments by analogy 1. All observed ravens have been black. 2. The observed ravens are analogous to the unobserved ravens. 3. [So] All ravens are black.

arguments by analogy 1. All observed ravens have been observed prior to The observed ravens are analogous to the unobserved ravens. 3. [So] All ravens are observed prior to 2010.

inductive arguments 1. Banana peel slips, last minute changes of heart, etc. have been uncommon in the observed cases. 2. [So] Banana peel slips, last minute changes of heart, etc., will not become common in the future.

inductive arguments 1. Banana peel slips, last minute changes of heart, etc. have been uncommon in the observed cases. 2. The observed cases are analogous to the unobserved cases. 3. [So] Banana peel slips, last minute changes of heart, etc., will not become common in the future.

the parody argument

1. If traffic to Hovander Park becomes common, then accidents on Neilsen Ave. will become common. 2. It is not the case accidents on Neilsen Ave. will become common. 3. [So] Traffic to Hovander will not not become common.

the parody argument 1. Accidents on Neilsen Ave. have been uncommon in the observed cases. 2. The observed cases are analogous to the unobserved cases. 3. [So] Accidents on Neilsen Ave. will not become common in the future.

inductive arguments 1. Banana peel slips, last minute changes of heart, etc. have been uncommon in the observed cases. 2. The observed cases are analogous to the unobserved cases. 3. [So] Banana peel slips, last minute changes of heart, etc., will not become common in the future.

counterfactuals A would-counterfactual is any counterfactual of the form If A had been the case, then C would have been the case. A might-counterfactual is any counterfactual of the form If A had been the case, then C would have been the case. A counterfactual of coincidence is any counterfactual where C would be a coincidence.

counterfactuals If I had tried to go home for lunch, then I might have slipped on a banana peel or had a last minute change of heart or… been prevented from going home for lunch in some other way. If I had tried to go home for lunch, then I would have slipped on a banana peel or had a last minute change of heart or… been prevented from going home for lunch in some other way.

the counterfactual coincidence argument 1. If time travel were possible, then the counterfactual coincidence principle is false. 2. The counterfactual coincidence principle isn’t false. 3. Time travel isn’t possible.

counterfactuals If I had tried to go home for lunch, then I would have slipped on a banana peel or had a last minute change of heart or… been prevented from going home for lunch in some other way. If I had tried to go home for lunch and not gone home for lunch, then I would have slipped on a banana peel or had a last minute change of heart or… been prevented from going home for lunch in some other way.