Category: Metaphysics

Since his creation, James Bond has been a white man. Much to the delight of some and to the horror of others, there were serious plans to have a black actor play James Bond. There has even been some talk about having a female James Bond. While racist and sexist reasons abound to oppose such changes, are there good reasons for James Bond to always be a white man? Before getting into this discussion, I will first look at the matter of the 007.

While James Bond has been known as 007, this is his agent designation and there are other 00 agents.  This is like the number used by an athlete on a team. As such, while James Bond has been 007, another person could replace him and get that number, just the person who was 23 on a baseball team could retire and someone else could get that number (although teams do retire numbers). Within the James Bond universe, it would make sense for someone who is not a white man to get the 007. This could occur for any number of in universe reasons, most obviously that James Bond is not immortal and would eventually be too old or dead to remain 007. From an aesthetic standpoint, it would be interesting to see a Bond timeline in which time mattered, a Bond world in which he grew old, and a new agent took his place. This would have the benefit of keeping Bond relevant to today while also maintaining (in universe) the old Bond. There is, of course, the obvious financial risk: having a new 007 who is not James Bond can be seen as analogous to replacing a star athlete with a new person who gets their number. There is the risk of losing the drawing power. But my concern is with the more interesting matter of whether James Bond must be a white man, so I will leave the money worries to the branding gurus.

One obvious fact about the Bond of the movies is that different actors have played the character. While there are strong opinions about the best Bond, there was little debate about whether a new white man should take the role when the previous Bond aged out of the role or left for other reasons. The actors who played Bond were (in general) accepted as at least adequate for the role and there was no debate about whether the character was James Bond despite the change in actors. That is, there is no general issue with a new actor playing the role. There was also, obviously enough, no effort to explain in the Bond universe the change in Bond’s appearance. I mention this because of another famous character from United Kingdom fiction, Dr. Who. When Dr. Who began, the actor playing the doctor was already old and they ran into the problem of age. They hit on a brilliant solution: Dr. Who regenerates and radically changes appearance, though remaining the same person. This gives the show an interesting feature: continuity of character through changes of actors with an in-universe explanation.

While Bond movies do feature gadgets and plots that border or even cross into science fiction (consider Moonraker), it is unlikely that the Bond cinematic universe would allow for such science fiction devices as alternative realities, such as in Marvel’s What If…? As such, the various Bonds are not explained in terms of being alternative or variant Bonds; they are all the James Bond. Now, if Bond can remain Bond despite the changes of actors, then it would seem that he would remain Bond even if he were played by a non-white actor. After all, if switching from Sean Connery did not mean that Bond was no longer Bond, then changing his race should not do that either. After all, the actors that played Bond are different people, with significant differences in appearance, mannerisms, and voice. Having a black actor, for example, would just be another change of appearance.  It would also seem to follow that having a female actor play Bond would also make as much sense; it would just be another change in appearance. But one could attempt to argue that it is essential to Bond that he be a white man. This, of course, gets us into the notion of essential properties.

In philosophy, an essential property (to steal from Aristotle) is a property that an entity must have or cease to be that thing. In contrast an accidental property is one that it does have but could lack and still remain that thing. To use a simple example, it is essential to a triangle that it be three-sided. It must have three sides to be a triangle. But the size and color of a triangle are accidental properties; they can change, and it will still remain a triangle. So, the relevant issue here is whether being a white man is essential to being James Bond or merely accidental. Given all the changes in actors over the years, there are clearly many properties that Bond has accidentally as they can change with the actors while the character is still Bond. One advantage of a fictional character is, of course, that the author can simply decide on the essential properties when they create the metaphysics for their fictional world. But, of course, the creator of Bond did not do that, so we need to speculate using various metaphysical theories about our world. That is, would a person changing their race or gender result in the person ceasing to be, just as changing the sides of a triangle would make it cease to be a triangle? On the face of it, while such changes would clearly alter the person, they would seem to retain their personal identity. If this is true, then James Bond need not be a white man. But more will be said in the next essay.

In philosophy, the classic problem of universals is determining in virtue of what (If anything) a particular individual is a member of a category. Some philosophers, such as Armstrong, Plato, and myself believe that at least some categories are metaphysically real and are thus as realists about properties. For example, if mass is a real quality, then entities with mass are grouped into that category in virtue of possessing that metaphysical property. A realist does not need to accept that all categories have a metaphysical foundation. For example, I take race and gender as human made ideas rather than being grounded in metaphysical entities. To use a less contentious example, I also take the property of being a citizen of the United States to be a social construct rather than a real metaphysical entity.

When talking about particulars being in categories, there are two general ways to view this. One is a matter of grouping: the property is what puts an entity into that category. There is also the matter of the entity being what it is in terms of the quality. These two can amount to the same thing but can be distinguished conceptually. For example, there is what it is for a green thing to be in the category of green things and the matter of what it to be green. Again, one might determine that these amount to the same thing. To illustrate, Plato would (probably) say that the Form of Beauty groups beautiful things into that category and makes a beautiful individual beautiful. I have not, of course, gotten into the epistemic aspect of this, such as how we know that something is in a category. I have also not addressed alternatives to metaphysical realism about properties. But for the sake of what follows, I will assume properties are real so that I can get on to discussing substances and substrata.

Philosophers such as Aristotle and Descartes accepted the existence of substance and define it as something that exists in a manner that does not depend on other entities. This can quickly get messy, but to keep it simple think of an everyday object like an apple.  It can exist as a distinct entity, apart from other things. Yes, I know that apples come from trees and depend on the existence of dimensions such as time; but I am keeping it simple here. The ability for an apple to exist on its own contrasts with that of its properties. To illustrate, I can buy an apple at Publix and take it home. I can take a bite out of it, taking that piece from the apple. But no matter how I bite it, I cannot bite away the property of mass or shape and have just mass or shape in my stomach. As such, properties are taken by many philosophers as not being substances. You can have an apple in your stomach, but you cannot have just apple shape or apple mass in your stomach. Because of this sort of thinking, philosophers such as John Locke have reluctantly accepted substance, calling it “something I know not what.” Others, of course, have rejected substance. If you accept properties as existing as part of substances, there is then the matter of whether the substance is just a bundle of properties or if there is another metaphysical entity that “binds” the properties together into a substance.

While bundle theorists have the advantage of metaphysical economy, they face the problem of explaining what connects the properties together into a single entity. Substrata theorists, like me, claim that there is a second type of metaphysical entity, the substrata. It has the function of binding properties together to form objects. While I have argued in favor of substrata at length, teaching the subject again in my Metaphysics class provided me with a metaphor that might help explain the matter.

Think of properties as being like paints and objects being like paintings. For those who just believe in properties and reject substrata, a painting would just be paint. Metaphorically, one would paint a painting by painting nothing; there would just be paint touching paint, forming a painting. Naturally, one could talk about letting some paint dry and then painting on that paint like a canvas, but there would be the question of what the first paint was painted on.

For those who accept substrata, the canvas (or other surface) would be like the substratum and the properties would be like paint: one paints on the canvas and the canvas plus the paint forms the painting. Naturally, metaphors and analogies tend to fall apart quickly when pressed. For example, one could say that one just needs to paint on the canvas until the paint dries, then peel the paint off. While this would be a flimsy painting, a painting made entirely of paint could thus exist. At least after it had been painted on a canvas. One could also reject the paint analogy or modify it in some manner so a painting could just be paint without a canvas. But the canvas and paint metaphor has a certain appeal.

This contains many spoilers. When I first saw the trailer for The Tomorrow War my thought was “I wonder who that discount Chris Pratt is?” When I realized it was the actual Chris Pratt, my thought was “he must really need money.” Yes, it is exactly that kind of movie. I will start with some non-philosophical complaints and then move on to what is most interesting (and disappointing) about the flick: time travel.

Like many war movies of its ilk, this flick handles armored fighting vehicles by leaving them out. Instead, the human forces confront the aliens with infantry, Humvees, transport helicopters, and fighter-bombers. Oddly, the infantry is armed with standard guns that are largely ineffective against the aliens.  This is even though they know this and there are plenty of existing infantry weapons that would kill the aliens. No armored fighting vehicles (like tanks) are used, and Humvees are the mainstay of the forces. They get easily destroyed by the aliens charging into them like deranged moose (except when the main characters are in one). Maybe leaving out armored vehicles is a budget issue, but it mainly seems because the aliens, which are basically animals, would be slaughtered by modern armor. They could do no damage, and antivehicle weapons would slaughter them. My theory is that rather than come up with an alien that could beat armor, the writers just leave out armored vehicles. The transport helicopters, as one would expect in such a film, generally fly within the leaping range of the aliens and attack helicopters do not exist (they do have armed drones, though). The fighter-bombers exist, as always, as a stupid plot device: in one part of the movie the hero is tasked with rescuing research that is the last hope for victory, yet an air strike is called on the otherwise empty city and it cannot be called off. But enough of that, on to the time travel.

Time travel is always a mess in philosophy, science, and fiction. But it can be fun if used properly. The movie does have an interesting, though unoriginal, premise: humans in the future have built a time machine and are using it to recruit soldiers and supplies from the past to fight the aliens that have killed all but 500,000 people. As movies must, the movie puts limits on time travel. The biggest limitation is that the time “tunnel” has a fixed temporal range of 30 years. When people go forward, they go forward thirty years. When they go back, they go back thirty years. One of the minor characters explains it in terms of two connected rafts in a river: they always stay the same distance apart but move along with the river. One of the supporting characters asks the obvious question as to why they do not make more rafts. The answer is that the time machine they have is held together with bubble gum and chicken wire, so they cannot build another one. While not the worst answer a writer could come up with, it is stupid within the rules of the movie: people and equipment can move freely between the present and future. More time machines could be made in the past and brought to the future. They could even build a time machine in the present and open a time tunnel to 30 years earlier, giving humanity another 30 years of preparation time. And then do that repeatedly until the paradoxes destroy reality. A better answer would have been some techno-metaphysical babble about how the time stream can only permit one time tunnel to operate. But let us get back to the fact that people and things can move between the times.

At one critical point in the movie, the heroes have completed a toxin that will kill the female aliens. But just as they complete it, their last base is overrun, and Chris Pratt is recalled to the past, with the toxin. The time machine is done, so the war has been lost. Apparently having struck his head in the fall, Pratt thinks he has no way of getting the toxin to the future, so everything is lost. The nations of the world also just sort of decide to give up as well, which would make sense if everyone believed in metaphysical determinism. Pratt’s character apparently lost the ability to understand how time works: the toxin he has in the present will eventually reach the future. It will just travel one day at a time towards that future.

Going back to the raft analogy, the time machine is like a pneumatic tube that has a fixed length, it can quickly move things back and forth over that distance. But, and here is how normal time works, one can also walk an object to towards the other end of the tube in the future. As such, when the aliens show up, the humans will have as much toxin as they wish to make to use against them. This feature of time would also allow the humans to plan their missions very effectively. To illustrate, I will use a smaller version of the time tunnel thing.

Suppose that on 12/5/2026 I build a time tunnel that reaches back 1 year (roughly). On that day, the tunnel pops open on 12/5/2025 and Mike 2026 can hand Mike 2025 a usb drive full of useful information (such as winning lottery numbers, weather reports, news reports on disasters, and so on). How would this be possible? Here is how. When Mike 2026 arrives, he tells Mike 2025 to fill up the drive. Mike 2025 spends the year doing just that, so in 2026 the drive is full of information and Mike 2026 hands it to Mike 2025 when he arrives.  Mike 2025 can now use all that information.

In the case of the movie, when the time tunnel opens for the first time, they could do the same thing: as people come from the future, they just update information. Thirty years after the time tunnel opens, the travelers have all that information and can use it to change missions that failed, and so on, thus changing the future. This, of course, creates the usual time travel mess of changing the future based on information from the future. An analogous problem also arises from bringing objects back from the future that depend on the future to exist. I will use the toxin from the movie to illustrate this old problem.

As mentioned above, Pratt’s character helps create a toxin in the future and brings it back to the past. He is weirdly baffled about how he will get it to the future but decides to not give up the fight. With the help of some others, he manages to determine that the aliens landed long ago and were frozen in the ice (like in the Thing). So, he does the sensible thing: he goes to a government official and tells him he knows where the aliens are and has the toxin to kill them. So, the official does the usual movie thing: he just refuses. So, Pratt and his associates do the usual movie thing and go it on their own. They use the toxin to kill a couple aliens, then blow up the alien ship (so they did not need the toxin). Then Pratt and his dad beat up the female that escapes the ship. The movie ends with everyone being happy. Except, obviously, the aliens and anyone who might have wanted the technology in that ship. Because of this, the tomorrow war never occurs. Which leads to some problems, but I will focus on the toxin.

The toxin only exists because it was created in the future in response to the aliens. To steal from Aquinas who stole from Aristotle, “To take away the cause is to take away the effect.” As such, the defeat of the aliens would mean that the toxin would never exist, it could not be there in the past. Also, going back to the information problem, Pratt only knows about the aliens because of the tomorrow war, which he prevented from happening. They could, of course, have done a “Yesterday’s Enterprise” thing: the whole timeline changes or something. This is just one of the many paradoxes of time travel.

Another approach, which one could mentally write into the movie if one wishes, is that time travel is dimensional travel or creates time-line branches (which is effectively dimensional travel). So, the future Pratt goes to is real and does not change for it is what it is. When he comes back from that future (alternative reality) with the toxin and kills the aliens in his present, this creates a new future timeline for him. This means, of course, that his alternative adult daughter dies in that alternative future, but his new alternative daughter does not, since the war does not happen in the new timeline.

The movie, I think, would have a been a bit more interesting if they used the alternative timeline approach and they could have had a brief moral debate about obligations to help in an alternate future of one’s own reality. Or it could be a plot twist that the people doing the “time travel” knew they were going to another reality but decided to lie about it to get help.

In terms of the quality of the movie as a movie; well, it is what one would expect from either a store-brand Chris Pratt or a name-brand Chris Pratt who really just needs the money.

As a runner, I have often imagined what it would be like to have super speed like the Flash or Quicksilver. Unfortunately for my super speed dreams, Kyle Hill has presented the fatal flaws of super speed. But while Hill did consider the problem of perception, he seems to have missed one practical problem with being a super speedster and that is how mentally exhausting (and boring) running a super speed could be. Kant can help explain this problem.

Our good dead friend Kant argued that time is not a thing that exists in the world, rather it is a form in which objects appear to us. It is for him, the “form of inner sense” because our mental events must occur in temporal sequence. Or, rather, must occur to us in that way. He does bring up a very interesting point, namely that other beings could experience time differently than humans. For example, God might experience all time simultaneously.  If God does this, it can account for both omniscience and free will: God knows what you will do because from his perspective you done did it, are doing it, and will do it. Other beings might have a similar inner sense, but with a different perceived speed. This takes us to speedsters.

While humans can operate fast moving vehicles like jets and rockets using our merely human perceptions, a super speedster would need to perceive the world and make decisions at super speed. Consider a simple comparison. With adequate training, I could pilot a plane going 500 mph. But imagine that I could run 500 mph, but my brain operated normally. If I tried to run a winding trail in the woods, for example, I would slam into trees because my running speed would vastly exceed my ability to perceive the trail and decide when to turn. But if my mental processes were also fast, then I would be able to run “normally” on the trail: from my perspective, I would have plenty of time to make decisions and avoid collisions. My “form of inner sense” would match up with my movement speed, so I would be fine. Mostly. But there would be a problem if I wanted to use my super speed to save on travel expenses.

Suppose I wanted to visit my family in Maine. My sister’s house is about 1500 miles from my house in Florida. If I could run 500 mph, I could be there in three hours. Being an experienced marathoner, I know that running for three hours is no big deal for me and it would be well worth it to save the cost and annoyance of flying. But travelling in this way would be more complicated than just running for three hours. For people watching me and by my watch, it would be three hours of running. But remember, my mind would be significantly sped up to enable it to handle my physical speed.

To keep the math simple, suppose my normal human running speed is 10 mph. So, my super speed would be fifty times that (500 mph). Suppose that my perception and decision-making speed was equally increased. While this might seem amazing, it would entail that from my perspective the three-hour run would take 150 hours (6.25 days). Even ignoring concerns about sleep and endurance, that would be an extremely unpleasant run. After all, I would experience it as if I were running there at normal human speed (although other people and things would seem to be moving very slowly). For me, it would not be worth it to spend 150 (mental) hours running even if it saved me the price of a plane ticket. After all, I could do that now—and I do not.

One could, of course, tweak the numbers a bit. Perhaps I could safely run at 500 mph while my mind operated at slower than 50 times normal speed. But it would still need to operate much faster than normal, otherwise I would keep running into things and doing a lot of damage. So, super speed would generally not be great for long distance travel.

One could, of course, do some comic book stuff and come up with workarounds to avoid the boredom problem. Perhaps a speedster would have multiple levels of awareness—a fast navigating subconscious awareness that guides them safely and a slower conscious mind to avoid the boredom. Going back to Kant, this would involve having two different forms of inner sense operating in the same mind, which is obviously not even very weird in philosophical terms. In that case, super speed would be a great way to travel.

By https://www.marvel.com/articles/movies/sdcc-2019-all-of-the-marvel-studios-news-coming-out-of-hall-h-at-san-diego-comic-con, Fair use, https://en.wikipedia.org/w/index.php?curid=62990603

If you have yet to see the first episode of season one of Disney’s Loki series, this essay contains spoilers. This episode presents some of the metaphysics of the MCU: there are many timelines (alternate realities) and variants of people, such as Loki and Deadpool, exist in some of them.

Loki is, obviously, the main character of Loki. In fact, he is two main characters: the anti-hero Loki and the hero-anti Loki (the villain). Since the metaphysics of the MCU includes time travel, this entails that the same person can be at different places at the same time. They can even fight, as happened with Captain America. While this is a metaphysical mess, this means time travel can be used as a multiplier: a person can time it so different versions of themselves arrive at the same place at the same time. So, for example, Loki could show up to fight an enemy at a set time and arrange for himself to go back or forwards in time ten times and end up with eleven of himself to overwhelm the foe. This, of course, leads to the usual paradoxes and problems of time travel. A future Loki could tell a distant past Loki about things that a middle past Loki did not know, but then the middle past Loki would know it. While this is even more of a mess, the time travelling Lokis could remain there in that time and start their own lives or perhaps travel back to a more distant past over and over to create a vast army of Lokis that meet up at a future time to do whatever it is that his character arc directs him to do.

Such time travel has various other problems. A point often made in time travel tales is the importance of not changing the past. Some sci-fi stories do allow a change in the past to change the future; other stories simply make it so that whatever the time travelers do is what happened anyway. That is, they make no change in the past because what they do is what they did and will always done did (Star Trek IV implies this). The classic grandfather paradox falls into this family of problems: if a person goes back to the past and changes things that impact their ability to go to the past (such as killing their grandfather), then they could not go back to change the past and hence the past would be unchanged and so they could go back to the past. But they could not, because if they made that change then they could not go back. And so on. In fiction, the writers simply write whatever they wish, but this does not address the matter of how this would all “really” work.

There is also the problem of personal identity: in the metaphysics of the MCU variants arise and a new timeline branch could presumably also spawn variants that create additional branches. As there are multiple Lokis in the show, they both spawned off the main timeline. Perhaps one Loki “divided”, or one Loki “split” from the other Loki. Or perhaps there are three (or more) Lokis: there is the Loki who remained on the timeline and was killed by Thanos. There is the Loki who escaped from the Avengers because of their time heist (the anti-hero of the show) and the third Loki who is the villain. Because of time travel, the third Loki might have split from the second Loki in the future. As always, time travel is a mess.

Having multiple Lokis does create the usual problems for personal identity. After all, what provides personal identity is supposed to make a person the person they are, distinct from all other things. As such, it would seem to be something that should not be able to be duplicated. Otherwise, it would not be what makes an entity distinct from all other things. If there are two Lokis in a room, there must be something that makes them two rather than one. There must also be something that makes each of them the Loki they are. But is this true?

One approach is taking inspiration from David Hume’s theory of personal identity.  After he argues a person is a bundle of perceptions, he ends up saying that, “The whole of this doctrine leads us to a conclusion, which is of great importance in the present affair, viz. that all the nice and subtle questions concerning personal identity can never possibly be decided, and are to be regarded rather as grammatical than as philosophical difficulties.” While this might be true, it does not satisfy. But it does provide a way of resolving a room full of Lokis: it’s a matter of grammar.

Another approach is trying to sort out the metaphysics of personal identity in the context of time travel. After all, time travel requires that entities can be multiply located while personal identity would seem to forbid duplication of what individuates. The reason time travel requires multiple location is that something from one time travels to another time and the matter or energy that makes up what travels will also be present when it arrives. So, the same thing will be in two places at the same time; something that is not normally possible. But one could accept the existence of metaphysical entities that allow this.

Yet another approach, and one that seems to match how the timelines were presented in the show, is that a branching creates an entire new reality that is similar but not identical to the first. This would also duplicate the people, perhaps creating them ex nihilo. So, the various Lokis would be similar people, but not the same person.

Dice (unloaded) seem a paradigm of chance: when rolling a die, one cannot know the outcome in advance because it is random. For example, if you roll a twenty-sided die, then there is supposed to be an equal chance to get any number. If you roll it 20 times, it would not be surprising if you didn’t roll every number. If you rolled the die 100 times, chance says you would probably roll each number 5 times. But it would not be shocking if this did not occur. But if you rolled a thousand or a million times, then you would expect the results to match the predicted probability  closely because you would expect the law of large numbers to be in effect. 

While dice provide a simple example, the world seems full of chance.  For example, diseases are presented in terms of chance: a person has X% chance of catching the disease and, if it can be fatal, they have a Y% chance of dying. While the method of calculating chance in the context of disease is complicated, the rough process involves determining the number of people in a category who become infected and the number in that group who die. To use a made-up example, if 1 person out of every 100 dies, then the chance of dying from infection would be 1%.

This estimate can be off for many reasons, but one obvious concern is that probability is being estimated based on the outcome. Why this is a problem is illustrated by considering a scenario in which you are given the results of repeated rolling of a die, and you are trying to figure out the type of die being rolled and whether it is weighted. You can, obviously, make some reasonable inferences. For example, if the highest number you are given is a 30, you know the die has at least 30 sides. Matters become more complicated if you are not sure that a die is really being rolled. Perhaps you have been given numbers generated by some other means. They might, for example, be selected to give the impression of chance. One could, for example, create the impression that they are rolling a 20-sided die by picking the appropriate numbers. A similar sort of thing could occur in the world, and this can be illustrated with the disease example.

Let us imagine two universes. Universe A is a random universe that has random chance and probability (whatever that means). In that world, there would be a metaphysical and metaphorical roll of the dice to determine outcomes arising from chance. For example, a disease that had a 1% fatality rate would work metaphorically like this: each infected person would get a roll with a 100 sided die (a d100 for tabletop gamers) and if they roll a 01, then they die. Thanks to the law of large numbers, if enough people got infected then this would work out to 1 in 100 people dying in this random universe.  Naturally, smaller numbers will not match the 1 in 100 perfectly, but with a large enough number of infections the 1 in 100 will be achieved (oversimplifying things a bit). Now to universe B.

Universe B is not random. It could be a deterministic or pre-determined universe or whatever non-random reality you want. In this universe the disease kills 1 in 100 people, but this is not the result of chance. Out of every 100 infected people, there will be one who will die (this oversimplifies things a bit for the sake of the example). This is not due to chance since this is not (by hypothesis) a random universe. In terms of why it occurs, this will depend on the sort of non-random universe one has picked. For example, perhaps the universe is run by a god who created the 1 in 100 death disease and has sorted out humans into groups of 100 using whatever standard the god has chosen and then selects one to kill with the disease.

From the standpoint of humans, this universe will (probably) appear identical to random universe A. After all, the samples people use will be imperfect and will create the impression that it is not a perfect 1 in 100 every time.  As such, it will seem random. Unless, of course, humans can figure out how the 100 person groups work. One could imagine a short story based on this idea in which scientists find that a disease is always fatal to 1 person out of a group of 100 people and the 100 person groups are divided up by the X factor they find. But if humans do not sort out the grouping, then the non-random universe would seem random because of human ignorance.

We do not, of course, know what sort of universe we live in. Roughly put, this might be a random universe and a 1 in 100 chance is “rolled” with metaphysical metaphorical dice. Or it might be a non-random universe in which a 1 in 100 “chance” means that it is “set” to happen once out of every group of 100. Unless we can identify the groupings and get adequate data, then we will never know what sort of universe we inhabit.

One approach to time travel is to embrace timeline branching: when someone travels in time and changes something (which is inevitable), then a branch grows from the timeline. This, as was discussed in the previous essay, allows a possible solution to the grandfather paradox. But it also gives rise to various problems and questions, such as the need to account for the creation of a new universe for each timeline branch. The fact that these universes are populated also creates a problem, specifically one with personal identity. Since I used the grandfather paradox as the context previously, I will continue to do so.

Suppose that Sally and Ted travel back in time and Sally kills her grandfather Sam. Ted does not murder his grandfather. Assuming the timeline branching solution to the grandfather problem, Sally creates a new timeline branch in which Sam is killed. While Sally does not exist (one assumes) in the new timeline, Ted does. There would be at least two Teds now: one that is in the original timeline and the Ted in the new timeline. In fact, anyone who was alive for the creation of the new timeline would presumably also in the new timeline as the entire population of the universe would be replicated. This raises some obvious questions about how this would work and issues within the context of personal identity. For the sake of simplicity, I will focus on Ted as my example, but this would also apply to anyone who ends up being branched.

To keep it simple, let us suppose that Sally and Ted are the first time travelers, so there have been no time branches. When they travel back, they create the first branch. While Sally will not exist in the new branch (and her act of murder might result in other people not existing or even new people existing), Ted will exist in both. So how would this work?

One option is to take the time splitting metaphor literally: the universe and the people in it are split into two. Think of this as like an amoeba dividing. This does raise the obvious question of whether whatever makes a person the person they are can be split. For example, Leibniz took a person to be a monad, and his monads are metaphysically simple: they cannot be split. But if personal identity rests on something that can be split up, then this would be possible. For example, Hume (sort of) advances a bundle theory of personal identity. On his view, the self is not a simple, indivisible entity. It is a collection or bundle of perceptions. To use a metaphor, just as a bundle of marbles could be divided up, this bundle could also be divided between timelines. This would lead to questions about trans timeline identity: would there be one divided person or two people who arose from a past person? In the case of Ted, there would be one Ted in each timeline, and they might (or might not) be the same person.

Another option is that the people in the new timeline are identical duplicates. This would require that the basis of personal identity be something that can be copied. Locke, for example, makes consciousness (memory) the basis of personal identity and even considers a case in which a person’s consciousness (memory) is duplicated. With a basis of personal identity that can be copied, the problem is solved: each new timeline person is a copy of the original. This also leads to the question of whether they are a trans timeline person or multiple different people who happen to have originated from the same person. One obvious consideration is that the basis of personal identity is supposed to be what makes a person distinct from all other things and this suggests that there should only be one of each person. But this view can be countered by arguing that it is philosophically fine to have multiples of the same person. This could be reined in a bit by limiting it to one person per timeline, the challenge would be justifying and explaining this restriction. On this view, there would be Ted in the original timeline and a Ted copy in the new timeline, who might or might not be the same person.

A third option is that the new timeline is a completely new creation that just resembles the original. The people do exactly resemble each other, but this is analogous to having two unrelated people that happen to look exactly alike: while the appear to be the same, this is not due to any connection between them. This is essentially an alternative reality view in which the reality begins with a timeline branch. While this does have some appeal, if the branch is not connected to the main timeline, then one must explain how it connects to time travel. One way to do this is to take the view that what seems to be time travel just creates an alternative reality and there is, in fact, no travelling. In this case, there would be a new Ted-like person who just happens to be exactly like Ted but has no metaphysical connection to the original Ted.

This matter becomes even more complex is one starts to consider theological and moral matters. For example, if God exists and people are souls that are sent to an appropriate afterlife, then God would need to sort out who is responsible for what. This should be super easy for God, barely an inconvenience. But without God, the ethics become more challenging: if a person is split into two people, which one is accountable for the past deeds? Perhaps they both are, like an amoeba who has split into two. If a new alternative reality is created and all the people are new, they should not be accountable for any past deeds, because they have no past at that moment of creation. Time travel is, of course, an even bigger mess than one would imagine.

The grandfather problem is a classic time travel problem. Oversimplified, the problem is as follows. If time travel is possible, then a person should be able to go back in time and kill their grandfather before they have any children. But if they do, then the killer would never exist and would not be able to go back in time and kill their grandfather. So, their grandfather would not be killed and they would exist and be able to go back in time and kill him. But if they kill him, then they would not exist. And so on. There have been attempts of varying quality to solve this problem and one is to advance the notion of timeline branching. The simple version is that time is like a river and travelling back in time to change things results in the creation of a new branch of the river, flowing onward in a somewhat different direction.

So, imagine that Sally goes back in time to kill her grandfather. She succeeds and thus creates a new timeline in which he dies. Presumably, she returns to her own timeline and finds that her original grandfather was never killed by her. She might keep trying and from her perspective she would kill him over and over, only to return to find that she never succeeds. But with each trip to the past, she creates another new timeline. For those who prefer their time travel murder free, any change a time traveler made would presumably create a new timeline and this would include the smallest change. Time travelers would certainly end up creating new timelines in which they (or, more likely, someone like them) exist and would probably keep traveling in time, thus creating branches off the branches. While having so many branches would seem excessive, there are metaphysical concerns for even having one additional timeline branch.

Each extra timeline branch would seem to require the creation of an entire new universe. But even if it created less than that, there would still be the same concern, albeit on a smaller scale. This concern is the origin of the stuff that makes up the new timeline. One solution is to just allow ex-nihilo creation: the new universe appears out of nothing, mostly duplicating the original with the relevant changes arising from the time travel. Allowing ex-nihilo creation would have implications beyond time travel and is generally considered sketchy metaphysics. It can, of course, be given a divine twist: God or other supernatural beings are kept busy creating new universes in response to time travel. This would also involve some interesting problems but is not any more problematic than having just one universe created by God or other supernatural being(s). As such, if you already accept that God can create a universe out of nothing, then the problem is solved. One could even endorse pantheism: everything is God and God just “creates” new modes “in” Himself that are the new timelines. Pantheism to the rescue.

A second solution is that the basic stuff (prime matter or similar) for new timelines already exists and just needs to be formed by whatever it is that does that sort of thing. The easiest answer is to just use whatever originated the first universe to fill the role of creating the new timelines. While there would be the question of why it keeps doing that, it seems sensible that if it can do it once, it can keep doing it.

In terms of the stuff, perhaps there is a finite amount of stuff and eventually time travel would no longer be possible because no new timelines can be created. But an easy fix is to make a clever appeal to the infinite: if there is infinite stuff, then no matter how much stuff is taken to make a new timeline universe, then there would still be infinite stuff left to keep creating new timelines. Infinity to the rescue once again.

One could also use various clever workarounds. For example, maybe solipsism is true and only I exist, so there would be no need to create new timelines. Or perhaps Descartes got it right and it is just him and the evil demon; the demon can just deceive Descartes about time travel without creating anything. But if the evil demon travels in time and changes things, then the problem would still arise. Or maybe there is actually nothing, no self, no reality and no time travel. In that case, there would also be no problem.

In sci-fi people upload their minds to machines and, perhaps, gain a form of technological immortality. Because of the obvious analogy to the way computer memory works, it is appealing to take uploading the mind as uploading memories. In fiction, the author decides whether it is the same person or not, but philosophers need to argue this matter.

While the idea of mind uploads might seem a recent thing, philosophers have been considering this possibility for a long time. On excellent example is John Locke.  On his view, a person is their consciousness, and he considered the possibility that this consciousness could be transferred from one soul to another. Locke’s terminology can get a bit confusing since he distinguishes between person, body, soul, and consciousness. But suffice it to say that on his view, you are not your soul or body. But you are your consciousness. Crudely put, this consciousness can be considered to be your memory. As far back as your memory goes, you go. The basis of personal identity is important: for you to achieve technological immortality (or as close as possible) it needs to be you that continues and not just someone like you.

Locke anticipates the science fiction idea of uploading your mind and considers problems that arise if consciousness makes personal identity and could be transferred or copied. His solution seems to be a cheat: he claims that God, in His goodness, would not allow this to happen. But if Locke is right about consciousness being the basis of personal identity and wrong about God not allowing it to be copied, then it would be at least metaphysically possible to upload your mind by copying your memories.

David Hume, an empiricist like Locke, presented an argument by intuition against Locke’s account: people believe that they can extend their identity beyond their memory. That is, I do not think that it was not me just because I forgot something. Rather, I suppose that it was me and I merely forgot. Hume took the view that memory is used to discover personal identity and then went off the rails and declared personal identity to be about grammar rather than philosophy. But even if the memory approach to personal identity fails, there are other options. One simple approach is to cheat a lot and just talk about the mind (whatever it is) being uploaded. The mind would, of course, also need to be the person otherwise it would not be you getting immortality.

Assuming the mind is the person, there are two possibilities: it can be copied/transferred or it cannot. If it cannot, then this sort of technological immortality is impossible.

Suppose that the mind can be copied. If it can be copied once, then there seems to be no reason why it cannot be copied multiple times. The problem is that what serves as the basis of personal identity is supposed to be what makes me who I am and makes me distinct from everyone else. If what is supposed to provide my distinct identity can be duplicated, then it cannot be the basis of my distinct identity. Locke, as noted above, “solves” this problem by divine intervention. However, without this there seems to be no reason why my mind could not be copied many times if it could be copied once. As such, a being might have a copy of my mind, just as it might have a copy of the files from my PC. There seems to be a paradox here: to have technological immortality, then the mind must be copyable. But if it can be copied, then it is not the basis of personal identity and it is not what makes you the person you are, distinct from all other things. So, if your mind can be copied, you are not your mind, and the copy will not be you. It will just be someone like you; a technological doppelganger. If your mind cannot be copied, then there is no technological immortality in the strict sense.  So, for the copy to be you, it would need to possess whatever it is that made you the person you are and what distinguished you from all other things: your personness and your distinctness. But perhaps the basis of identity could be transferred rather than copied.

One interesting possibility is that the mind could be transferred from a biological system to a new technological one. In this case, you would be transferred rather than copied. It would be like handing off a unique item as opposed to creating a copy. In this case you could achieve technological immortality. Your original body might keep living, but if you are transferred whatever that entity is it would no longer be you. It would be like a house you once occupied. This, of course, is analogous to possession: an entity takes over a new body by transferring into it.

As a final possibility, it is worth considering that the Buddha is right: there is no self. In this case, you can never upload yourself because there is no self to upload.

George enjoyed and hated the privileged position of being the grandson of Edgar the Tyrant, the man who had killed his kindly brother Sam. Edgar had conquered the Seven Systems with alien technology and established the most crushing despotism in human history. Like his grandfather, George was a brilliant scientist with a special talent for understanding alien technology. Unlike his grandfather, George was burdened with ethics and compassion. After discerning the secrets of an alien time machine, George nobly decided to sacrifice himself by going back in time and killing his grandfather before he discovered the trove of alien technology that enabled his reign of terror.

After travelling back in time and locating his target, George took careful aim with the alien plasma rifle, confident that the heavy weapon would guarantee the death of his grandfather. It did exactly that, vaporizing not only him but several meters of ground.

George expected to be erased from time instantly, but in realizing that he still existed he realized he still existed. Thinking that it might take some time for the effects to catch up to him (or head back to him, however it worked) he sat down to wait. And wait. When nothing happened, he thought “hmm, maybe that rumor about grandma and Uncle Sam was true after all” and travelled back to his time.

 

Time travel, as any time traveler will tell you, is problematic. One of the classic problems is the Grandfather Paradox. If you can travel in time, then you should be able to go back in time and kill your grandfather (or grandmother, to avoid sexism in temporal murder). However, if you kill your grandfather, then you would never exist and would not be able to go back and kill him. As such, time travel would make it possible to kill your grandfather but killing him would make it impossible for you to kill him. Hence the paradox.

One solution is to take it as a reductio ad absurdum of time travel. If time travel were possible, it would lead to an unacceptable paradox. Therefore, time travel is not possible. Another approach is to address the paradox with a bit of temporal deus ex machina: you can travel back and time and try to kill your grandfather, but you will never be able to succeed. If you, for example, try to run him over with a car, you will run out of gas or get a flat tire. If, as another example, you try to shoot him with a rifle, every round will miss or misfire. Or you will get caught by the police. There is an obvious question of how this temporal enforcement mechanism would work.

One could, of course, invoke a teleological explanation: there is a purposeful agent that ensures that you will never succeed. As with non-time travel teleological agents, this could be a supernatural being (God or a god of time), mortal agents (time cops, perhaps) or some sort of Aristotelian temporal paradox-preventer (perhaps related to the first mover).

In the context of doing metaphysics in accord with the economic style of argumentation, using a teleological metaphysical entity to solve the paradox would raise the cost of the theory. As per Occam’s razor, entities should not be multiplied beyond necessity. Metaphysical teleological explanations also tend to be out of favor in philosophy, especially those of the supernatural sort. This will tend to impose both a “weirdness” and implausibility cost on the theory.

But this cost can be offset if the entity provides enough benefits, such as explanatory power. On this economic model one chooses between metaphysical theories in a way analogous to choosing between smartphones: the one with the best benefits for the lowest cost would be the winner.

Having mortal agents prevent the paradox could make for interesting science fiction (and imposes no metaphysical cost) but there is an obvious problem: mortal agents could fail. While one could argue that time police would have a huge advantage over a lone time-traveler, there are easy-to-imagine scenarios where even a lone time-traveler succeeds. One could imagine, for example, a rogue time cop deciding to kill their grandparent. Because of this, fallible protectors of time would not solve the problem.

Another approach would be to embrace a form of non-teleological determinism: while one could travel back in time one can never succeed in killing one’s grandfather because one failed. This would seem to have broader implications for time travel as well in terms of making any changes to the past. This does raise the question of how this determinism would work but determinism (in its various forms) is already a well-established philosophical position. As such, if you are already a determinist, then you can presumably apply it to time at no extra cost and solve this problem.

Science fiction has other options that could solve the problem. One approach taken by Alfred Bester  in “The Men Who Murdered Mohammed” is that going back in time to commit murders does not affect the timeline, but instead affects the traveler by gradually removing them from reality. While the mechanism for this would need to be explained, it does solve the paradox: you could go back and kill your grandfather, but this would have no impact on the timeline. You would just fade a bit, metaphysically speaking, and history would remain unchanged.

Another approach is that time travel creates alternative timelines. The traveler goes back and murders his grandfather and thus creates a new timeline in which this occurred. The original timeline (whatever that might mean) remains intact. The time traveler might also split and they would exist in the original timeline because nothing changes there. But they would not exist in the “new” timeline: they killed their grandfather in that timeline and hence would never be born. Since time travel is mysterious and messy, perhaps the time traveler would be exempt from the split in some manner. Or perhaps not.

This approach does raise some obvious problems. One is that time travel would seem to create new timelines ex nihilo: they seem to simply come into existence from nothing. Unless, of course, the original timeline gets sliced like a pizza, something that would seem to be, at least in theory, detectable. Then again, if the original timeline is infinite, dividing infinity results in infinities. Another set of problems would involve personal identity. If the split occurs, what happens to the identity of the people in the original timeline and those “created” in the new timeline? For example, if Sally goes back and kills her grandfather and splits the timeline, then there would be a new timeline with the people from the original “duplicated” (perhaps including her grandfather if a there is an afterlife). To illustrate, consider Sally’s grandmother Sarah. When Sally kills her grandfather and splits the timeline, then there would now be at least two Sarahs. Both arose from the unsplit Sarah, so they would both seem to be Sarah. But they are now two people unless there is some form of cross timeline personal identity. Some theories of personal identity can easily handle this. For example, Locke’s consciousness-based theory would entail that both Sarahs were the original Sarah (if their memories remain) but they are no longer the same person after the split because they have different memories. Theories, like Descartes’, that make the person the soul would need to account for there being two souls: does the original divide like an amoeba or does a new soul get created? Or something else? All these issues (and others) need to be addressed to make this solution work.

While there are numerous problems that arise from this approach, it does not require postulating the existence of new types of metaphysical entities: one just needs multiples of what we already have, namely the timeline. This does not raise the ontological cost of the theory. To use an analogy, if one accepts the existence of one supernatural god, accepting a second or tenth god comes with no extra ontological cost. The price is paid for each metaphysical type rather than each token of that type. There might be other costs arising from this, though, such as matters of weirdness or plausibility.

The last approach I will consider is that time travel is dimensional travel. That is, when you travel in “time” you are going to another reality that is at a different time than your reality. On this view, when someone travels “in time” to kill “their” grandfather, they are travelling to an alternate reality and killing an alternate version of their grandfather. In that reality, “they” would not exist, but they could return to their own reality, which would be one in which their grandfather was not killed by a time traveler. This would be analogous to killing the grandfather’s twin brother: this kills someone like him but not him.

While this approach does require explaining how dimensional travel would work, it has fewer problems than the split timeline approach. While it does require multiple dimensions, so does the split timeline approach. But it does not require that they appear ex-nihilo or form from division. It also does not face the problems with personal identity: the person in the other reality is not the traveler’s grandfather, just someone similar. The obvious downside to this approach is that it solves the problem by eliminating time travel. But maybe that is a good thing.