# Time travel the grandfather paradox ii. lewis’s puzzle A. Tim can kill Grandfather. B. Tim cannot kill Grandfather.

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time travel the grandfather paradox ii

lewis’s puzzle A. Tim can kill Grandfather. B. Tim cannot kill Grandfather.

lewis’s puzzle A. Hud works with those people. B. Hud doesn’t work with those people.

lewis’s puzzle A. Hud works with Dan and Frances. B. Hud doesn’t work with Ben and Zoe.

lewis’s puzzle A. Tim can kill Grandfather. B. Tim cannot kill Grandfather.

lewis’s puzzle A. Tim’s killing Grandfather is compossible with the R facts. B. Tim’s killing Grandfather is not compossible with the R+ facts.

lewis’s puzzle A’s X-ing is compossible with facts F 1 -F n iff there is some possible world in which F 1 -F n obtain and A Xs.

the altered past paradox 1. If time travel is possible, then one can change the past. 2. One cannot change the past. 3. [So] Time travel is not possible.

the fatalist argument 1. It is either true that Hud will eat dinner tonight or true that Hud won’t eat dinner tonight. 2. If it is true that Hud will eat dinner tonight, then his eating dinner is unavoidable. 3. If it is true that Hud won’t eat dinner tonight, then his not eating dinner is unavoidable. 4. [So] Whatever happens—dinner or no dinner—is unavoidable.

the retro-suicide paradox 1. If time travel is possible, then one can commit retro-suicide. 2. One cannot commit retro-suicide. 3. [So] Time travel is not possible.

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