Back to the Future – Metaphysics of Time and Time Travel.
by Bryn Gatehouse
Throughout history, time travel has taken a mythical role. Beginning in the realm of prophecies and oracles, the modern age has confirmed a continued obsession with the possibility of knowing what will happen, and changing what has happened. This is a basic way of understanding the motivations of Doc Brown and Marty McFly in a scientific manner, a question of possibility and of empirical observations, made through Doc’s plutonium powered car. The pair test both the possibility and the limits of time travel, and through an incestuous encounter with Marty’s mother they engage with the most famous paradox in the logical area of time travel – the grandfather paradox. As the pair move throughout time, from the 1950s of Marty’s parents to the old West, or forward to the mesmerising age of 2015, their hijinks test the boundaries of logic and our engagement with the world, simultaneously engaging with the thought of Einstein and relativity.
A trail of fire left from the DeLorean, Back to the Future I, Universal Pictures.
As a preliminary I would like to point out the fact that the Back to the Future series (Robert Zemeckis, 1985-90) already engages with philosophy, specifically the philosophy of time, through its use of time travel at all. Whilst scientifically uncontroversial, as one only has to point to Einstein’s theories of relativity and the plane of spacetime, the statement that there are different times at all finds itself with logical problems. One of these is that the thought that all times are equally present, and thus reachable as Marty and Doc do a number of times, contradicts Leibniz’ law, which states that for something x to be identical to something y, x and y must share ALL the same properties. In the case of Back to the Future, Marty at the beginning of the first film does not share all the same properties as Marty at the end of the first film. In order to avoid this, whilst keeping Leibniz’ law, one can instead deny the existence of all time excluding the present. This would change the way our sentences operate when speaking of time. For example, existential statements such as “Marty exists in 1955 and 1985” would be changed for the sake of clarity to “Marty existed in 1955 and exists in 1985”, assuming that this statement is uttered in 1985, perhaps by Doc or Marty. If this seems outright silly, ask yourself this: do dinosaurs exist? Or did they exist? If the second is true, we may be more inclined to this presentist picture of time.
Similarly, we may be inclined to say that the past and present exist, but the future does not. This growing block theory opens up the possibility of free will, which some may find important when theorising. But, in an interesting addition to the franchise, the second film denies us this opportunity, for how can one travel to the future without a future already existing to travel to? When removing the distinction between time and space one may be inclined to think of this spatially – can you drive to a location that does not exist?
Marty being shorter than his Dad in 1955, Back to the Future I, Universal Pictures.
Just as Back to the Future rejects the presentist theory of time in favour of the infinite possibility of time travel, unfortunately including relationships with your own mother and almost jeopardizing your own birth, we may reject the presentist picture of time using Marty himself, along with his father George. Take this statement - “Marty in 1985 is shorter than George in 1955”. This is true, as Marty travels back as one entity, remaining the same in 1955 and at that point is clearly shorter than his youthful, perverse father. Accepting this, we may now ask what makes this true? For, if George in 1955 did not ‘exist’ at the time of the statement being uttered, but only ‘existed’, what is one pointing at (or referring to, to use philosophical language) if not George? Thus, the logic of Back to the Future is (maybe a little shakily) restored, allowing reason to flow through the film once more. But, just as for most rivers, another blockage appears on the horizon, much larger than before, an ugly dark mass of paradox that threatens to destroy the logical integrity of the entire genre of time-travel fiction, not just Marty’s little adventure to seduce his own mother.
Marty with his Mum in 1955, Back to the Future I, Universal Pictures.
The grandfather paradox is simple, and even features within Back to the Future. As Marty relentlessly pursues his own teenage mother, thus using the magic of science to turn his own father into a cuckold, his family photo begins to fade. The corruption of Ms McFly by her sick son has resulted in Marty’s entire life to have never happened. But, if this is the case, how would Marty have possibly existed and grown in such a way as to travel back in time to lead his mother astray from the only future in which Marty exists? This is the root of the grandfather paradox. Of course in the film Marty fixes the timeline in which he is born, but the very possibility of this occurring presents a paradox so large that we may be forced to deny the possibility of time travel at all, thus denying Marty the opportunity he so (unconsciously) desires, that being to make a pass at his own mother.
What are the consequences of this paradox for the logic of Back to the Future? Simply this: Marty necessarily cannot change the past, nor the future in the case of the second film. This is as, in order to subscribe to the universal picture of time in Back to the Future, everything that has happened and will happen exists just as the present does. Allowing this picture of time, Doc’s time-travel machine may only work alongside the grandfather paradox if Marty makes no effort to change the past, nor the future. But, he does. Whilst paying no heed to the devastating consequences of eternalism to any concept of free will, Marty is now denied the ability to change the past at all, thus denying his arc throughout the film – but can Marty possibly change the past? Why should we deny any attempt to change the past at all? This is simple, it is illogical. Human life, along with everything else, can only exist within a logical framework that sets the boundaries for any distortion of the past, the present or the future. Marty can change the past in some ways, but one can only accept this if they can accept that Marty has always changed the past. Take the case of Marty’s introduction of Johnny B. Goode to the world. This is acceptable, only if one is willing to say it has always been the case that Chuck Berry stole from a California teenager in 1955 word for word, bar for bar.
The logical boundaries of the structure of reality are daunting and bright, allowing Marty no chance to change his own future. Marty could spend his life training to seduce his mother and would fail to even fall out of the tree that leads to him meeting her. The likelihood is that logic would not act in any spectacular way, no figure would appear and bear down upon Marty and his mother in bed, but the event simply would not occur. Perhaps Marty would trip up, or lose his voice, all resulting in history occurring as history has already occurred. Back to the Future becomes an illogical mess, as the unfurling of the paradox blocks any pre-natal incest from occurring.
by Bryn Gatehouse, June 2023.
