1. the double-occupancy paradox
time travel
the double-occupancy paradox

2. the psychologist’s argument
If the time machine were traveling into the future, we would see it right now.
We don’t see it right now.
[So] The time machine isn’t traveling into the future.
If the time machine were traveling into the past, we would have seen it on Thursday.
We didn’t see it on Thursday.
[So] The time machine isn’t traveling into the past.
If (3) and (6), then the time machine isn’t traveling in time.
[So] The time machine isn’t traveling in time.
the psychologist’s argument

3. the psychologist’s argument
If the time machine were traveling into the future, we would feel it right now.
We don’t feel it right now.
[So] The time machine isn’t traveling into the future.
If the time machine were traveling into the past, we would have felt it on Thursday.
We didn’t feel it on Thursday.
[So] The time machine isn’t traveling into the past.
If (3) and (6), then the time machine isn’t traveling in time.
[So] The time machine isn’t traveling in time.
the psychologist’s argument

4. If the time machine were traveling continuously into the future, we would see it right now.
We don’t see it right now.
[So] The time machine isn’t traveling continuously into the future.
If the time machine were traveling continuously into the past, we would have seen it on Thursday.
We didn’t see it on Thursday.
[So] The time machine isn’t traveling continously into the past.
If (3) and (6), then the time machine isn’t traveling continuously in time.
[So] The time machine isn’t traveling continuously in time.
The revised argument

5. the double-occupancy paradox
If continuous travel into the past is possible, then double occupancy in possible.
Double occupancy isn’t possible.
[So] Continuous travel into the past isn’t possible.
the double-occupancy paradox