The Instigator
Pro (for)
0 Points
The Contender
Con (against)
8 Points

this argument proves that people cant travel back in time

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Voting Style: Open Point System: 7 Point
Started: 2/21/2013 Category: Philosophy
Updated: 3 years ago Status: Post Voting Period
Viewed: 875 times Debate No: 30459
Debate Rounds (3)
Comments (1)
Votes (2)




i believe that the argument below is proof that people cant travel back in time. CONs goal is to find an irreconcilable logical hole in my argument. give your rebuttals in the 1st round. state every point that you would disagree with and why.
consider this scenario:
P1. Bob's son is named Fry
P2. Fry traveled back in time
P3. Fry killed Bob, resulting in Bob never having a son

based on P3, Bob never has a son, but according to P1, Bob did have a son. this is a contradiction, so at least one part of the scenario must be logically impossible. let's go through them: is it logically impossible to have a child? no. is it logically impossible to kill someone? no. is it logically impossible to not be a parent? no. is it logically impossible to travel back in time? MAYBE.
Given that one part of the scenario must be logically impossible, and the only part that might be logically impossible is backwards time travel, then backwards time travel must be logically impossible.


Thank you for giving me the opportunity to have an honest debate with you. Good Luck.

My rebuttals will be as follows:
1) the flaw in the breakdown of the scenario
2) the 3 most popular time-space continuum theories
3) media portrayals of a very similar scenario ('Looper')

Before beginning with my rebuttals, am I right in assuming P3, P2 and P1 refer to the Persona series of video games?
Just a personal question.

1) It is wrong to assume that some part of the scenario NEEDS to be logically impossible. After many years of schooling and practicing of higher level physics I have learned many things. One thing that i have come to realize is that when the answer is not perfectly clear nothing is impossible. Based on special relativity, time slows down when moving at speeds close to the speed of light. The theory also states that at the speed of light, time stops. Based on this, one could say that by going faster than the speed of light, one could reverse time in their frame of reference and thus move backwards in time. Another theory states that one would need an infinite amount of energy to move at the speed of light. At this time, neither theory has been fully proven correct or fully proven false. It is very possible that at least one of these theories is wrong. It is impossible to say something is impossible until you can prove it unequivocally.

2) Your argument also assumes a very specific time-space continuum. The theory you are using is that time is perfectly linear and any change in the past will in turn change the future. In this sense, you would be perfectly correct. Fry killing his father before he himself is born would make it impossible for him to be born and in-turn make it impossible to kill his own father, making his father survive and him being born. In this scenario then, theory also states that it is possible to create an infinite loop in which Fry is born and un-born, killing his father and not killing his father. Thus, all time after which Fry goes back in time never exists and the world ends at the exact time Fry leaves the "present".

Another theory is the split-continuum theory. At the exact time in which Fry, or someone in a different scenario going back in time changes the past (i.e. killing someone, buying something, telling someone the future, etc) another universe instantaneously appears, parallel to the original in which the future takes place completely independent from the original timeline. In this theory, Fry CAN kill his father and exist at the same time. He has successfully created a new universe in which he is not born but exists. Yay paradoxes.

This next theory is one of my favorites in terms of how hard it is to understand, Much like the first, this theory has only one timeline. Based on this specific scenario, when Fry goes back in time and kills his father, he does effectively prevent his own birth, but that does not create the paradox in which he never existed. The instant that Fry left the "present", he is no longer affected by the space-time continuum. When he kills his own father and prevents his future birth, he is unaffected and remains in the past as a paradoxical entity (much like ghosts, if they exist).

3) MAJOR SPOILERS!!! In this scenario, a man is sent to the past to be killed. It is clean and nearly impossible to find the body. One man kills himself from the future who was sent back in time. He lives through his whole life before he inevitably sent back in time in order to be killed by his younger self. He then fights against his younger self and survives. Based on the most accepted theory (#1 of rebuttal 2), the instant he made the decision to fight against his own death would have changed everything in his mind (whether to rebel, his wife and his life as a whole). Using media as a source (as i assume you did as well), you are wrong.

~again i wash you luck and a thank you.
Debate Round No. 1


"do P3, P2 and P1 refer to the Persona series of video games?"
no, i dont know what youre talking about

anyway, you said "It is wrong to assume that some part of the scenario NEEDS to be logically impossible."

it sounds like you agree that part of my scenario is probably false, but you just disagree that part of the scenario must be impossible? this is a good point to bring up, and i will try to explain why it's not an assumption. let me illustrate by using an example: i consider being a married bachelor to be impossible, rather than something that is possible, but just hasnt happened or wont happen. saying it's possible means that you think a contradiction could be true, but speaking logically, it is impossible. it's not just false to say Bob is a married bachelor, it is impossible that anyone is a married bachelor.

now let me put it this way; let us assume for now that backwards time travel is possible. if so, then P1, P2, and P3 would all be able to occur, which means that a contradiction would be true if and when those things happened. but that would contradict logic. doesnt that mean that some part of it is impossible?

all the other points you made are arguments for the possibility of backwards time travel. but first of all, they are only theories and dont prove conclusively that you can travel back in time, and secondly, they don't refute my logic. indeed, i dont know everything about how time and space work, but if my argument is valid and sound, then my conclusion must be true, regardless of anything else


As you stated in the first argument, I am not here to prove that time travel is possible. I am here to prove that the way in which you "disproved" time travel is not correct. "CONs goal is to find an irreconcilable logical hole in my argument." Whether or not the theory is correct, it disproves your argument. When you stated your original scenario, your conclusion was based on THEORY about the space-time continuum. Thus, an answer using THEORY about the space-time continuum would effectively prove or disprove your argument.

When I said that anything is possible, I meant that anything is LOGICALLY possible. Special relativity has more or less been proven [1].

As I stated in my previous argument, scenario is entirely possible based on MULTIPLE theories. Just because you feel you can prove that time travel is not possible under a specific theory's frame of reference doesn't mean it is holistically impossible. We have no way to prove that any of the a fore mentioned theories are wrong or right. My goal, as you stated. is to say that your argument is not guaranteed, which I feel has been done.

Debate Round No. 2


time being different wouldnt cause a hole in my logic
let's say i said this:
1. if roses are red, then time exists
2. roses are red
conclusion: time exists
if premises 1 and 2 were true, then the conclusion would have to true, regardless of what the nature of time is. time is just a variable. you could replace it with X, and the logic would be valid. defining the variable wont falsify the logic.

this is what that would look like:
P1. Bob's son is named Fry
P2. Fry did X
P3. because of X, fry was able to never be born
if you knew that a contradiction could happen if Fry were able to do X, then you would have to conclude that X is impossible. it doesnt matter what X is. if X is the source of the contradiction, then it is impossible, regardless of what the nature of it is. Con has failed to understand this. if there is a hole in my logic, Con hasnt found it. vote PRO.


Unfortunately, I have come to the understanding that my opponent is not using any scientific facts or reasoning for a question that is essentially pure science based. Although I feel that I have portrayed my side correctly, my opponent will never see things from my point of view. The point of an argument is to view all sides, choose one and state the ways in which the other(s) is(are) wrong. I at least hope that those who view and/r choose to vote on this argument are able to understand both perspectives and determine for themselves what is most likely.

To the instigator: Induced, the true hole in your logic is the inability to understand another's logic. I thank you for the opportunity to discuss this topic with you and I wish you luck on your future endeavors.
Debate Round No. 3
1 comment has been posted on this debate.
Posted by likespeace 3 years ago
Pro made a similar argument once before, with a similar outcome--
2 votes have been placed for this debate. Showing 1 through 2 records.
Vote Placed by Deadlykris 3 years ago
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Total points awarded:03 
Reasons for voting decision: Pro's logic is inherently flawed, as was pointed out by Con. The example with the rose shows that clearly - roses have nothing to do with whether or not time exists, so P1 is invalid. C cannot be considered based on an invalid P1, even when P2 is demonstrably true.
Vote Placed by likespeace 3 years ago
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Total points awarded:05 
Reasons for voting decision: Con explained that under multiple theories of time P1, P2, and P3 could simultaneously be true. The problem in Pro's argument was the assumption that "one part of the scenario must be logically impossible." Con pointed that out. The resolution did not task Con with proving time-travel was possible, simply with pointing out the problem in Pro's argument, which he clearly did. Update: Con also posted the only source and it supported his position.