Introduction
David Lewis, in his work, The Paradoxes of Time Travel, posits that time travel is possible and adds that; paradoxes surrounding time travel are not impossibilities but oddments. In this paper, the writer imagines that an author writes a science fiction story about time travel.
In the story, a poor scientist in 2010 uses a time machine to travel back to 2008, where he/she tells his younger self the winning lottery numbers for 2009. The time traveler uses the time machine to return to 2010, where he is now rich. The writer then uses Lewis’ arguments to criticize the story and suggest how Lewis would revise it. To understand this story, it is important to understand some of Lewis’ arguments.
Lewis on Time Travel
Lewis observes that, “time must not be a line but a plane” (146). This implies if two events are separated more than once in time dimensions, then they can have two one-sided separations. In normal life, people live on straightforward aslope lines cutting across the plane of time. However, a time traveler lives on bent-line slopes on the same time plane. Moreover, according to Gott, time traveler has a personal time that does not comply with the rules of the normal time, also called external time (5).
In this case, the time traveler’s personal time can go back into ancient time in the present external time. Nevertheless, this phenomenon is relative and Lewis notes that the probability of a time traveler going back in time to change the past depends on some set facts. Lewis therefore would find a foothold to criticize the aforementioned fiction.
The Criticism
As aforementioned, the author writes a story where a poor scientist in 2010, goes back to 2008, reveals to his younger self the winning numbers of a 2009 lottery; wins the lottery, and comes back to 2010 where he or she is rich. Lewis would say that this scenario could not happen because of inconsistency.
Lewis would consider some few facts here. The poor scientist cannot be rich in 2010. This poor scientist is poor right now, therefore going back in 2008 and reveal to his/her younger self the winning numbers of a 2009 lottery, would be tantamount to changing the past, which cannot change.
Lewis would argue that, events surrounding “past moments are not sub divisible into temporal parts; therefore, cannot change” (151). Events of 2008 can either timelessly include the poor scientist revealing to his/her younger self the lottery winning numbers or timelessly do not include the events; however, the two events cannot occur simultaneously.
If the fiction story were to be considered true, the possibility of describing two events referring to same thing would be inevitable. In this case, there would be ‘original’ 2008 and ‘new’ 2008.
The ‘original’ 2008 would represent the actual time when the poor scientist lived and did not know anything about the winning lottery numbers; on the other hand, the ‘new’ 2008 would represent a counterfactual time when the poor scientist is revealing to his/her younger self the winning numbers of the lottery. In the time traveling world of this poor scientist, both the ‘original’ and the ‘new’ 2008 exist in his/her extended timeline; however, in the external time people would be referring to the same thing.
Unfortunately, one event cannot be defined or described by two different events. If the poor scientist did not reveal to his or her younger self the winning numbers in the ‘original’ 2008, but he reveals the numbers in the ‘new’ 2008, then he/she must both reveal and not reveal the winning numbers in 2008, because there can only be one 2008 which is both the ‘new’ and the ‘original’ 2008.
Therefore, logically speaking, the poor scientist cannot reveal to his/her younger self the winning numbers of the lottery; consequently, he or she cannot be rich in 2010.
Lewis’ Revision Strategy of the Story
Instead of giving a one sided story, Lewis would opt to give it two sides considering what the poor scientist could do and what he/she could not. The first scenario is that of the poor scientist not revealing to his/her younger self the winning numbers of the lottery as explicated in Lewis’ criticism. In revising this story, Lewis would argue that the poor scientist would reveal to his/her younger self the winning of the lottery.
Here are some facts that would facilitate this occasion. The poor scientist would change his/her poverty status in the past by revealing to his younger self the winning lottery numbers; however, he/she would fail to do that, not because of any impossibility but because of some inefficiencies. Given the fact that the poor scientist did not reveal the winning numbers in the original 2008, consistency requires that he/she does not reveal them in the ‘new’ 2008; why?
There has to be a reason why the poor scientist could not reveal the winning numbers to his/her younger self. Maybe he/she lost the paper containing the numbers or simply doubted the authenticity of the numbers. In this case, the poor scientist has the potential to reveal to his/her younger self the winning lottery numbers; however, something crops up which changes the fate of this poor scientist. This is normal in life; people try hard to do things that they would wish to; however, fate has it that they fail.
Not because it is impossible to do such things, it is only that luck does not allow it. In this case, some eminent contradictions would sabotage the consistency of the story. One, the poor scientist does not reveal the numbers even though he can for he/she has them. Two, the poor scientist does not reveal the numbers, and he/she cannot for the past is unchangeable. According to Sider, Lewis would argue that, ‘can’ is equivocal; hence, the two scenarios are compatible (1).
To say the poor scientist ‘could’ reveal the winning lottery numbers is compossible with contextual facts; that is, he had the numbers. The poor scientist could reveal to his/her younger self the winning lottery numbers just the way a teacher can read out answers to students. However, the poor scientist could not reveal the numbers to his young self because this scenario is not compossible with some other facts, he/she is poor in 2010, and this is the fact.
Nevertheless, interpreting these two scenarios calls to choose either a wide delineation and conclude that the poor scientist cannot reveal the numbers or a narrow delineation of relevant facts and conclude that he/she can reveal the numbers.
Relativity takes precedence here and either of the arguments can pass as true; however, one cannot afford to conclude that the poor scientist could and could not reveal the numbers simultaneously. The call to make choice here is to root out contradiction, which would otherwise refute the possibility of time travel.
Conclusion
Lewis points out that time travel is possible; however, one has to make a choice and argue his/her case out based on relativity of facts surrounding the subject under study. In the case of a poor scientist in 2010 traveling through a time machine to 2008, revealing to his younger self the winning numbers of a 2009 lottery, winning it and becoming rich in 2010, Lewis would criticize it on basis that, the past is unchangeable.
However, Lewis would revise the story and throw in a possibility of such an event happening depending on the relativity of facts surrounding it. The poor scientist did not reveal the numbers to his younger self but he/she could do so because he/she had the numbers; however, he/she failed for he/she either misplaced the paper containing the numbers or simply doubted the authenticity of the same.
On the other hand, the poor scientist did not reveal the numbers to his younger self and cannot because the past is unchangeable. The fact is, in 2010, the scientist is poor, and it depends on the stand that one takes in interpreting the possibility of this poor scientist going back to 2008 to reveal the winning numbers to his young self. Nevertheless, one cannot say that the poor scientist can and cannot travel back to 2008 simultaneously.
Works Cited
Gott, Richard. “Time Travel in Einstein’s Universe: The Physical Possibilities of Travel.” New York; Houghton Mifflin Company, 2001.
Lewis, David. “The Paradoxes of Time Travel.” American Philosophical Quarterly. 1976: 13(2); 146-152.
Sider, Ted. “Lewis on Time Travel.” Nd. Web.