Book:The Paradox of Convergent History
In an alternate history timeline, convergent history (or OTLism) refers to events subsequent to the point of divergence which share many elements in common with, or directly parallel to, corresponding events in OTL history. Typically, this only applies to events that are directly affected by the butterfly effect stemming from the PoD. Given a soft interpretation of the butterfly effect, then any region or aspect of society that are distantly removed from the PoD may be expected to follow OTL history for a long time, and are thus not considered to be convergent history. In other words, if the butterfly effect pushes ATL and OTL histories apart, then convergent history is whenever the two timelines start to pull back together.
For example, say a timeline has a point of divergence where Harold Godwinson wins the Battle of Hastings. Under normal conditions, even a soft interpretation of the butterfly effect would predict that the entire history of Great Britain after this point should be radically changed. Thus, any subsequent events which are either parallel to or share many elements in common with OTL British history are considered to be an OTLism. For instance, events which are equivalent to the Anarchy, the War of the Roses, the English Reformation, etc. This still applies even when the exact names and circumstances of the parallel events are changed, like changing the War of the Roses to something like "the War of the Axes".
Sometimes, OTLisms can be much more subtle. Suppose a timeline has the Spanish Empire colonize the continental United States instead of England. The colonial history of America, and the circumstances of the American Revolution, are totally different from OTL. However, the principle leader of the ATL American Revolution is named Jorge de Guasa (a loose translation of "George Washington" in Spanish), and his actions/personality have many elements in common with OTL George Washington, even though everything else in the timeline is changed. In this case, not only is George Washington an OTLism, but also the fact that the American Revolution happens during his lifetime (as opposed to any other time period, if at all).
Sometimes, an OTLism may appear in a completely different time and place from their OTL counterpart. For example, suppose a timeline has a completely original civilization to develop in 15th century South Australia, but the events of its history borrows many elements from Mycenaean Greece. This is still an OTLism, even though the original counterpart is from a completely different region and time period.
In popular fiction, convergent history is often used as a solution to cases of malicious time travel. A malicious actor travels back in time and creates one point of divergence, then the protagonist goes back in time to create another point of divergence that "fixes" history. In this case, the reader is expected to believe that the second PoD creates a butterfly effect that cancels out the first PoD, such that the second ATL is virtually indistinguishable to OTL history. The 1985 movie Back to the Future is one famous example, although it still acknowledges that some residual butterfly effects still exist in the second divergent timeline (like George McFly becoming wealthier, etc.).
The paradox of convergent history refers to a phenomenon across many timelines in the multiverse in which the appearance of convergent history relative to the point of divergence runs counter to intuition. Intuitively, events in ATL history should become more divergent from OTL history the more time passes from the PoD, due to the butterfly effect. Thus, timelines with an older PoD should more radically different in the present day than timelines with a more recent PoD. However, the consensus of timelines across the multiverse tend to reflect an opposite trend: universes with a more recent PoD tend to be more radically changed in the present day, while older PoDs are more likely to result in convergent history.
To illustrate this idea, notice that many timelines using a PoD within the last hundred years will often result in a world that is radically divergent from OTL, where many facets of society such as politics, culture, or even ethical standards are effectively turned upside down (for example, if the world becomes dominated by fascist or communist ideologies). But for timelines with a much older PoD, such as thousands of years ago, it's a different story. Events relatively close to the PoD, like within the first two hundred years, will tend to be drastically changed with respect to the butterfly effect. But as time goes on, the events of the timeline start to become more and more familiar. There will be some events that are effectively equivalent to the Renaissance, the Enlightenment, the Industrial Revolution, etc., albeit the names and circumstances surrounding these events may be changed. If the timeline reaches the modern day, there will often be some version of World War I and II, and even a subsequent Cold War and nuclear age. By the 21st century, the world is dominated by moderate liberal democracies, exactly like OTL, despite the fact that the civilizations spawning these liberal democracies didn't even exist historically.
This runs counter to intuition, resulting in a paradox. It is expected that worlds with an older PoD should be more divergent than one with a more recent PoD, not the other way around.
There are many possible explanations for this paradox, as well as the proliferation of OTLisms in general, all of which fall on a spectrum. On one side of the spectrum are Doylist approaches, which explain the paradox as a result of the author's own decisions, limitations or biases. The multiverse on the Wiki is a collection of fictional stories, and their human authors are susceptible to basic pitfalls of creative writing. In many cases, the proliferation of this phenomenon can be seen as a common mistake of novice writers (and some veteran writers, too). On the other side of the spectrum is a Watsonian approach, which exxplain the paradox as an intrinsic mechanic of the multiverse itself, despite being counterintuitive. There are many cases where using an OTLism is completely justified, without compromising the plausibility of the timeline. In fact, there are many others cases where (it can be argued) using an OTLism is actually more plausible than not using one.
No single explanation will fit every scenario, and each case of OTLism should be individually judged for its plausibility, based on whether it can maintain a suspension of disbelief. The rest of this article will examine each possible category an OTLism can fall into, listed in order from Doylist to Watsonian, and provide examples of scenarios where an OTLism of that category might be justified.
Historical Variations
A historical variation is a general aesthetic associated with one specific nation, region, or civilization at one or more distinct eras of OTL history. This aesthetic can be distinguished by a wide variety of factors, including but not limited to: political organization, state ideology, dominate language, dominate religion, social structure, or economic paradigm. One factor not typically utilized is the technological level, because it is generally assumed that any historical variation has the potential of still existing in the modern day, given the right point of divergence.
Take Italy for example. Each era of OTL Italian history has its own aesthetic, which comes from a combination of the cultural, social, and political organization unique to that era. So the historical variations of Italy could be listed as something like this:
- Classical city-states
- Roman Empire
- Germanic petty kingdoms
- Holy Roman Empire
- Mercantile republican city-states
- Napoleonic puppet-state
- Nationalist, constitutional monarchy
- Fascist dictatorship
- Unitary liberal republic
- Historical variations are not an objective measurement, but are up to individual interpretation and subjective opinion. In the list above, the pre-Roman history of Italy could be subdivided between Etruscan kingdoms and Hellenized city-states; the Roman Empire could be subdivided between Republic, Principate, and Dominate, and so forth.
Some nations have many more historical variations than others, depending on how long that nation has had recorded history. Australia, for example, has effectively only two (Aboriginal Australians and the British Dominion).
In writing alternate history, many authors have a tendency to pigeon-hole each nation into one of its historical variations, or sometimes a combination of two or more variations. For instance, a PoD more than two hundred years ago has equal potential of modern China either becoming a dynastic empire, a nationalist republic, or a communist state. Brazil will either end up as a Latin American republic or a constitutional empire (occasionally neither). Oftentimes, the choice of historical variation is a direct consequence of the butterfly effect, while other times it is more of an educated guess (in cases of a very old PoD, or a hard butterfly effect). Sometimes, however, the choice is totally random.
Historical variations is not a recommended approach to alternate history, but the phenomenon is pervasive among many writers, especially those who are relatively new to the craft. The most obvious flaw in the system is that the author is artificially limiting themselves to only consider what incarnations did happen, without opening their imagination to the infinite possible incarnations that could have happened. It suggests that the author is so deeply accustomed to some parts of OTL history that they struggle to imagine a world without it.
In extreme cases, rigid adherence to historical variations will create massive holes in plausibility. For example, if a timeline has a significant PoD in western civilization from five hundred years ago, then there is no plausible explanation for how the United States could sill form under exactly the same circumstances as OTL (i.e., breaking any suspense of disbelief). Or as another example, if a butterfly effect prevents the rise of Islam from happening, then the appearance of any Islamic state after that point is ASB by default. This kind of scenario exemplifies the worst form of OTLism, where copying OTL history is objectively more implausible than choosing any ahistorical variation at random.
It is possible that the author is subconsciously influenced by popular media, or cultural stereotypes, such that they cognitively associate a certain nation with a limited set of aesthetics. For instance, they could be so used to imagining Egypt as either Pharaonic or Muslims, that they never consider a world where Egypt is actually Jewish or Zoroastrian (despite both scenarios being quite plausible, given the right PoD).
This is also a major reason why so many timelines include a World War of some sort in the 20th century. The Second World War is so iconic to that century, and iconic to alternate history in general, that passing over it simply feels very empty and incomplete for a lot of people, even if the PoD is so old that the belligerents, casus belli, or even civilization itself have become virtually unrecognizable. Of course, this doesn't apply as often if the PoD is specifically about preventing the world wars. Even among them, there are a good number of timelines that starts out trying to avoid World War II (such as preventing Hitler's rise to power), but end up having it anyway (usually because of Joseph Stalin).
In fact, the prevalence of historical variations tend to get worse the further away it is from the PoD. For instance, if the PoD is specifically about curtailing the rise of Islam, then any competent writer will take note that Egypt should probably be Christian instead of Muslim. But if the PoD is distantly removed from Egypt, then it becomes increasingly more likely that the writer will make the nation end up converting to Islam one way or another, even if the circumstances around the rise of Islam are radically changed by the butterfly effect.
In a similar vein, there is a tendency for timelines to arbitrarily stop historical development of a nation that happens to be contemporary to the PoD, even if there is no logical connection by the butterfly effect. For example, a PoD in Ancient Rome ends up having China remain under the Han Dynasty to the present day, whereas a PoD in the Islamic Caliphate will keep the Tang Dynasty in the modern day, etc. This only ever happens in timelines with a soft butterfly effect, for obvious reasons.
In a broader sense, almost every single "overused trope" of alternate history can be described as a manifestation of historical variations. Some examples include:
- Inevitable Republic of Deseret: the State of Utah has very few historical variations, due to its relatively short recorded history. Unless the timeline has American westward expansion just like OTL, or a civilization of Ute People (the latter being very unlikely), then the only possibility left is a theocratic democracy like Deseret. This is chiefly why that nation is so ubiquitous across the multiverse. Even in timelines with a PoD so old that Mormonism can't exist, there is often some ahistorical religion that happens to bear enough similarities to Mormonism such that Deseret is still founded
- The Kazakh Border: almost all historical variations of Kazakhstan (the Kazakh Khanate, the Uzbek Khanate, etc.) terminates their territory at the foot of the Eurasian Steppes, around the same latitude as Lake Boktal and the Altai Mountains. This leads many writers to ensure every nation in that region shares the same border as OTL Kazakhstan, despite the fact that the OTL border follows no specific natural barrier
- Divided Italy: despite Italy being unified in OTL, many writers appeal to the historical variation of Italy when it was divided between mercantile republican states (among other forms of government).
- United India: many writers associate India as a united state, mostly due to the modern incarnation under the Indian Federation, as well as a number of historical variations in which India was mostly unified (the Mauryans, Gupta, Delhi Sutanate, Mughals, etc.)
- Randomonian Congo: at first, it seems like this wouldn't apply, because it is specifically putting Congo under a different nation than historical. However, this trope is still caused by historical variations, because every timeline still utilizes a kind of Free Congo State very similar to OTL, but merely change the name of its colonial master.
- Nothing happens in South America: the historical variations in Latin America have very little impact on the OTL history of the western hemisphere, with the United States and Europe taking most of the limelight. Timelines that create a more relevant South America tend to focus heavily on the Inca Empire, the only centrally-organized pre-colonial variation.
The use of historical variations should not at all be a source of derision to the timeline author. Everyone has biases, and part of the joy of learning is to understand our biases from a different point of view, and experiment with something new. At the same time, the mere presence of an OTLism does not automatically make it the result of a historical variation, as will be explained in subsequent sections.
Stylistic Choice
One potential problem of using an OTLism is that it invites the audience to make a comparison outside the bounds of the timeline's universe, which runs the risk of breaking the reader's sense of immersion. In some cases, however, this feeling of comparison can be deliberately harnessed in order to make a statement that extends beyond the timeline itself.
In the 1997 novel Back in the USSA, the 20th century history of America and Russia are perfectly reversed, such that events in ATL America run parallel to the OTL history of the Soviet Union, and vice-versa. The reader is invited to make a comparison, which makes a broader statement of what it would be like for Americans to live under the USSR. In another example, say a timeline has the Central Powers win the First World War. The writer may decide to create a fascist government in France that is deliberately parallel to OTL Nazi Germany, which makes a broader statement of how easily a democratic nation can be led down a dark path.
In some cases, an OTLism can be used for historical irony. For instance, a world where John Wilkes Booth goes into politics and is elected President in 1864, only to be assassinated exactly the same way as he assassinated Lincoln in OTL. It's the kind of gesture that is meaningless to the characters in-universe, but is appreciated by the audience.
The deliberate use of OTLism can feel heavy-handed at times, but it can also be used to communicate some rather subtle information. If the birth of a child is described in a way that shares many elements in common with the Nativity of Christ, then it signals to the reader that this is the beginning of a major ATL religion, even if the timeline never explicitly says it. If a nation in a timeline shares many elements in common with the Roman Empire, that can communicate that this nation will have a lasting impact on future civilization, as Rome did for Europe. On the other hand, if the nation has elements in common with the Mongol Empire, that could suggest that it will collapse in a few generations and become mostly forgotten. If a timeline generically mentions a city gets sacked, that could just be an unfortunate happenstance. But if the writer deliberately copies the OTL Gothic Sack of Rome, that signals to the reader that the empire's days or numbered, even if this ATL empire is far removed from Rome in space and time. Of course, all of these things can instead be accomplished by examining the underlining mechanics of history, rather than copying from OTL, but it works just as well.
In order to make a timeline into an engaging narrative, there is a lot of wisdom that can be gleaned from treating the nations of a timeline as if they were characters of a story. It just so happens that contemporary OTL history (particularly World War II and Globalization) lends itself towards a satisfying third act. In many cases, the "meat" of a timeline (extending from the point of divergence up until the 20th century) follows the lifespan of two or more rival Great Powers (i.e. the protagonists and antagonists), which are constantly competing over territorial, economic, ideological, or religious domination. By the modern period, the reader will be anxiously looking forward to seeing how that tension is resolved, and a climactic global conflict is certainly a satisfying way of accomplishing that. After the climax, the proliferation of international organizations (like the United Nations or the European Union) serves as a satisfying epilogue, as the victors in the global war come together to usher in a new age of cooperation and prosperity. It fills the same role as a wedding in a Shakespearean comedy, as the great powers are "married" into a multi-national union.
That being said, OTL history is certainly not the only way of reaching a satisfying conclusion of the story, and the writer should judiciously decide which ahistorical scenario fits their narrative best. One could argue that the OTL Cold War is rather "anti-climactic": many timelines could benefit from mixing things up with a Nuclear Holocaust, or a multi-polar Cold War, or never inventing nuclear weapons at all. Perhaps the timeline focuses on the lifespan of one specific nation instead of multiple Great Powers, in which case it might be better for the timeline to climax with some sort of internal conflict or Balkanization. Or perhaps the nation was already conquered by the antagonist, and the timeline climaxes with its war of independence.
Of course, these suggestions based on stylistic choice only really apply if you approach a timeline having a specific narrative in mind. There are more than a few writers, espoused to a hard butterfly effect, who may frown on such a practice. They will argue that a timeline should strictly follow a realistic chain of cause and effect, and not follow any overarching narrative. These tend to be the same people who will reject the use of OTLisms altogether. As discussed later in this article, however, the fanatical disregard for any OTLism comes with its own set of problems.
Plausibility Benchmark
Plausibility benchmarking is a process of using events in OTL history as a baseline for understanding what is possible in an alternate timeline. When a timeline is approached as a blank slate where almost anything can happen, it becomes very non-trivial to determine if the current direction of the timeline is plausible. For a soft approach to the Butterfly Effect, the recommended process is to start with the point of divergence and follow a direct sequence of cause-and-effect, selecting the scenario with the highest probability (i.e., the most plausible outcome). This is indeed the best approach in the short term, but over time the margin of uncertainty is so large that it becomes very difficult to determine the probability of each scenario. And if the author selects an outcome at random, it runs the risk of being so unprecedented that it breaks the reader's suspension of disbelief, and thereby losing plausibility.
Plausibility benchmarking solves this problem by first determining what paradigm or niche of OTL history the current state of the timeline is most similar to, and then use that to estimate where the timeline should most likely go next. After all, it is a lot easier to argue that a scenario is possible by comparing it to something that actually happened (since no one would deny that events in OTL history are possible, although some are more likely than others). Imagine a timeline describes a tribal confederacy that is organized by a charismatic religious leader, who manage to conquer multiple neighboring empires in less than a hundred years. Ordinarily, the probability of this scenario would be fairly low, except that this is exactly what Muhammad accomplished in the seventh century AD. So as long as the reader is able to accept that this ATL figure is "like Muhammad", then they are more likely to accept the scenario as a whole, and therefore not consider it contrived. And once suspension of disbelief is achieved, so is plausibility.
As another example, imagine a timeline that makes an original civilization in medieval South Australia. Due to a lack of written records, it is not physically possible to follow an explicit chain of cause and effect. If the civilization is developed in a random or unprecedented way, it runs the risk of breaking any sense of immersion. But if the author instead imitates the history of other river valley civilizations, such as Egypt, Mesopotamia, or the Indus Valley, then plausibility is much easier to maintain. Once the reader is willing to accept that this scenario is "like Egypt", or "like Mesopotamia", then they are likely to accept the timeline as a whole. Alternatively, this same outcome could be achieved by understanding the underlining mechanics of civilizations as a whole.
So the process of plausibility benchmarking effectively uses OTL history like a painter's palette, where the uniqueness of a timeline comes from the combination or implementation of events rather than the events themselves (just how the colors of a palette are not unique, but their combination and arrangement on the canvas is). If the timeline involves a relatively-isolated but advanced island nation, the author can draw inspiration from the history of Japan. If the timeline is about heavily-mercantile landlocked state, the writer should instead look into the Ghana Empire. If the timeline includes a great monarch whose legendary deeds are larger than life, then the author can borrow elements from King David or Sundiata of Mali. If instead the monarchy has a child on the throne, then the timeline can go in a number of different directions, depending on if the writer draws inspiration from Edward V of England, Pepi II of Egypt, Manasseh of Judah, etc.
The fact of the matter is, OTL history is so incredibly vast and diverse, that there is practically no plausible scenario that hasn't already happened at some point in the recorded past (or, in many cases, multiple times). Trying to find a scenario that hasn't happened in OTL history is like trying to find a completely original color, or a joke never used by the Simpsons. It is partly for this reason that there is a common understanding among fiction writers that imitating the patterns of previously-proven works is not inherently a bad thing. And if you set out to make a timeline that is completely original, with absolutely no OTL analogues whatsoever, your head will probably explode. So rather than trying to deliberately avoid OTLisms, the author should embrace OTL history as their arsenal of tools.
In mathematical terms, imagine that every single timeline that could ever be written (whether or not it actually has been written) is arranged along a probability distribution, according to how likely it is for each timeline to happen. One can assume that OTL history sits at the exact center of the Gaussian curve, i.e. the most probable timeline out of all of them. Of course, there is no way to know if such an assumption is actually true, but for the time being (until humanity develops sufficient technology to traverse parallel universes) that is the only data point we have to work with.
Based on that assumption, then the likelihood of every other timeline is directly proportional to how similar they are to OTL history. So this effectively creates an alternate definition for plausibility: a timeline is more plausible the more similar it is to OTL (even if that does make it more "trivial"), and less plausible the more radically unprecedented it is (for example, if an empire forms or collapses much faster than any other nation in history, then it is implausible). This definition makes sense in most practical cases. For example, as long as Islam forms in the Arabian peninsula, then Egypt has a very high probability of converting due to its proximity and cultural similarity. Otherwise, the next-most probable scenarios are a Christian or Zoroastrian Egypt, and so forth, whereas a radically-unprecedented religion like Shinto or Cao Dai has an extremely low probability of becoming dominate.
It is important to emphasize that plausibility benchmarking only works if the OTL counterpart is similar in ways that are relevant to the scenario. For example, the Indus Valley civilization is fundamentally connected to its river valley, and thus cannot be expected to behave the same way if their history is applied to Alaska or the Sahel. A scenario that originally happened in Feudal Europe may not make much sense in the Victorian Era, even less so in the United States. Plausibility benchmarking is intended to enhance and guide the plausibility of a timeline, not be detrimental to it.
One common problem with plausibility benchmarking is how often it gets abused by certain individuals in order to wank nations they are personally attached to. They will borrow just enough elements from the Mongol Empire in order to justify a rapid territorial expansion, but simultaneously give it the longevity of Pharaonic Egypt, and also the technological advancement of the British Empire, without ever considering that all of these traits could not possibly exist at the same time. While each individual event from OTL history is highly plausible, an overly-contrived combination of events or applying scenarios inappropriately is just as capable of doing damage to suspension of disbelief.
Deliberately picking-and-choosing the best possible traits for the author's preferred character is precisely the building blocks of a Mary Sue, the bane of all fanfiction writing. A textbook example of a Mary Sue in alternate history fiction is the Draka Saga by S. M. Stirling. This ATL South African nation uses a kind of OTLism, borrowing America's historical Manifest Destiny to justify its rapid expansion across the entire African continent. However, this timeline is ASB, because it fundamentally misunderstands what enabled America's expansion in North America couldn't be applied to a different continent (if it could, the historical Union of South Africa would certainly have done it).
Cosmic Solipsism
Cosmic Solipsism is a concept in which certain individuals or other entities are destined to behave in similar ways across their alternate counterparts in the multiverse. Solipsism is a philosophical concept that a person's soul is distinctly-separate from their physical body, which is a doctrine that is shared among the orthodox beliefs of many world religions and spiritual traditions. Cosmic Solipsism takes that concept to its logical extreme, saying that a person's soul remains constant even when the physical world is radically changed. This means that souls can never be altered by the Butterfly Effect, since the butterfly effect can only ever affect the physical state of the world.
In practice, Cosmic Solipsism is commonly used to introduce an OTL historical figure, even when the context they are born into has been radically changed. In a world where Harold Godwinson wins the Battle of Hastings, William Shakespeare's soul is still destined to be a great playwright, even though in ATL his plays are performed for an Anglo-Saxon monarch. In a world where the continental United States is colonized by the Spanish Empire, George Washington's soul is still destined to lead the colonies to independence (given that something like the American Revolution still happens). In a world where the Dark Ages never happen and technology is much more advanced, Albert Einstein's soul is still destined to make some kind of revolutionary scientific discovery comparable with the Theory of Relative.
One character commonly brought up by Cosmic Solipsism is Napoleon Bonaparte. Many timelines speculate on what would happen if Napoleon was born under different circumstances, such as a world where Genoa does not sell Corsica to France, or sells it to a different country instead, or if Napoleon's parents immigrated to a different region such as colonial America. Most of these writers take the assumption that, regardless where Napoleon is born, he is destined to become a military and political genius, and will transform his home country into a great power that redefines history of the western world, just as he did with OTL France. Similar concepts are also applied to the birth of other political or military giants, such as Hannibal Barca or Joseph Stalin.
Cosmic Solipsism is easier to justify for a historical figure whose achievements were already revolutionary or unprecedented in OTL. The circumstances of Genghis Khan's empire was already so unlikely, that it would appear that any major change to Central Asian history could only work more in his favor.
For similar reasons, some of the most common uses of Cosmic Solipsism is the advent of major religions. The creation of evangelical religions such as Christianity, Islam and Buddhism were already considered revolutionary ideas in OTL, even without considering their claims to divine revelation. And if divine revelation is factored in, then it is self-evident that God or other celestial beings are not going to be affected by the Butterfly Effect, so one would expect their corresponding prophetic messages to still happen regardless of the circumstances on Earth. For example, the angel Jibril is still going to give Muhammad the Quran in 610 AD, even in a world where Mecca is being ruled by the Achaemenid Empire or Pharaonic Egypt. This doesn't mean that the religion would still be successful or widespread, just that the initial spark from the spiritual realm still takes place.
Of course, Cosmic Solipsism cannot apply in situations where the PoD is specifically about changing a character's life, or if the character's life decisions are directly impacted by the Butterfly Effect. In a world where Martin Luther pursues his original goal to become a lawyer and never joins the church, no cosmic force is going to compel him to start the Reformation like OTL. Cosmic Solipsism is a kind of tongue-in-cheek explanation for how an ATL historical figure mirrors his OTL counterpart, in a timeline that is already considered plausible. Cosmic Solipsism should never be used as an in-universe explanation for why events play out the way they do, nor is it a substitute for a plausible chain of cause-and-effect in the physical world.
There are some cases where entities other than people are introduced with Cosmic Solipsism, such as nations or social movements. The most common example is the Inevitable Republic of Deseret. This is extremely rare, however, and it's hard to apply it without causing issues of plausibility somewhere down the line.
Gambler's Fallacy
The Gambler's Fallacy derives from a misconception of how known probability distributions affect the outcome of statistically-independent events. If you flip a coin, the probability of it coming up heads is one-half. If you flip the coin nine times, and it comes up tails every single time, you might conjecture that the probability of getting heads on the tenth flip has now increased, because you've only gotten tails so far. However, that is not the case. Each coin flip are statistically-independent events, so the probability is still one-half no matter how many times it is flipped.
Whenever a timeline uses convergent history (that is, when the subsequent history of the timeline becomes gradually more similar to OTL), there is a natural tendency from many people to call that implausible. This is true in many cases, whenever the prerequisites of the convergent history are precluded by the Butterfly Effect (for example, a world where Islam never forms but the history of Indonesia remains unchanged). That being said, it may not always be the case, and there are many situations where a convergent history is just as plausible as not converging history, albeit not as imaginative.
It is understood that almost every event in a timeline, including the PoD itself, is not deterministic, but instead generates a probability distribution of multiple possible outcomes. One can further assume that this is a uniform distribution (it almost certainly isn't, but this is just a simplifying assumption for the sake of the argument). Among all the possible outcomes from this event, at least one of them may share many elements in common with OTL history. This means that the scenario that leads to convergent history is equally probable (and therefore equally plausible) as every other scenario that doesn't involve convergent history.
For example, imagine a timeline where France conquers the Aztec and Inca Empires instead of Spain. There are a vast number of possible ways that the subsequent history of Latin America could play out, of which some of them may bear many similarities with OTL (merely substituting Spanish names and institutions for French equivalents). If this is a uniform probability distribution, then those scenarios with convergent history are equally plausible as the scenarios that are not convergent.
There is a kind of knee-jerk reaction to assume that convergent history must always be implausible, on the grounds that ATL history happening to align with OTL history is a very unlikely coincidence. However, this is faulty reasoning that stems from our bias as living in an OTL universe. The fact of the matter is that every timeline in the the multiverse, including OTL history, are statistically-independent of each other. Therefore, the conjecture that convergent history is somehow less likely than any other scenario is effectively committing the Gambler's Fallacy. Uncreative? Yes, but not implausible.
Chaos Theory
In addition to the scenarios listed above, this question can also be examined using a mathematical argument based in probability distributions on a large scale. This argument will demonstrate that can convergent history be plausible, but in some cases it is critically necessary, such that the absence of OTL analogues is actually more implausible than having one. Furthermore, this argument can also give a fully in-universe solution for the paradox of convergent history, explaining why a PoD near the present is expected to result in a more divergent timeline than a PoD in the distant past.
According to the law of large numbers, general statistical patterns can be predicted deterministically from a sample of random numbers of a known probability distribution, as long as the sample size is very large. For example, if you flip a coin ten times, then you expect to get five heads and five tails. In practice, this is very often not the case. However, if you flip a coin ten thousand times, then you are pretty much guaranteed to get heads exactly 50% of the time, or very nearly close to it. As long as you know what statistical patterns to expect from the probability distribution, then the behavior of random numbers become more consistent and predictable as the sample size increases. Contrariwise, as the sample size decreases then the behavior becomes more chaotic and harder to predict.
In terms of alternate history, one can define the "sample size" as the amount of history covered in the timeline, spanning from the PoD to the present day, and the "random generator" as the set of historic events that happens in ATL history after the PoD. In this case, "known statistical patterns" refers to the set of historic events that are expected to occur in any civilization, both historic and fictional, given enough time. If the PoD is very close to the present day (like in World War II), then the sample size of the timeline is relatively small. Therefore, there isn't enough time for predictable statistical patterns to emerge, and the timeline ends up very divergent from OTL as a result. However, if the PoD is set in the distant past, like thousands of years ago, then the sample size is much larger, and therefore more likely to exhibit statistical patterns that are similar to OTL (and, by the same logic, similar to every other timeline that lasts equally as long).
A similar analogy can be made using thermodynamics. A point of divergence is akin to an unstable system of heated gas. But the more time passes, the more the system cools down until it reaches a state of equilibrium.
To illustrate this idea in a very simple example, imagine a world where Albert Einstein never existed. Would the Theory of Relativity ever be discovered? It's certainly conceivable that relativity would be discovered at some point. But Einstein lived so close to the present, and the theory itself is so incredibly counter-intuitive, that it is highly likely that a timeline terminating in the present day would never see that discovery happen. Now, instead imagine a timeline where Pythagoras never existed. The lack of a Pythagorean Theorem would certainly set back the history of mathematics for a while, possibly even a couple hundred years. But in the two thousand years since that time, does it really make sense to say that nobody would have ever developed the same theorem? The odds seem to be astronomically small. So in the first example, history becomes more divergent (Theory of Relativity in OTL and none in ATL), while in the second example history converges (both OTL and ATL having the Pythagorean Theorem), as a direct consequence of having a much older PoD.
There is nothing intrinsically special about the present, but in our corner of the multiverse it provides a hard upper limit to the length of a timeline because every timeline on the Wiki must end in the present day. Given enough time (beyond the 21st century), a PoD in World War II will eventually start to converge as general statistical patterns start to emerge. Contrariwise, a PoD that collapses the Roman Empire in 200 AD will look extremely divergent from OTL for the first few hundred years.
What kind of events count as "predictable statistical patterns"? They would have to be broad socio-political or cultural movements, which occur gradually over a long period and spread out over a large area. It cannot be an event tied to one specific cause or the decisions of one individual person, but rather should be a natural consequence of civilization reaching a certain level of development. This would include such events as an agricultural revolution, Bronze Age, Classical Period, as well as a Renaissance, Enlightenment, and Industrial Revolution. On the other hand, events such as World War II or Alexander the Great are much too specific to fall into this category. The writer cannot just spawn Alexander into their timeline and claim that it is the result of Chaos Theory, as that would be the equivalent of predicting one specific data point as falling into one specific part of the Gaussian Curve, which wouldn't make sense.
It is easier to justify an OTLism under Chaos Theory if it is a pattern observed in multiple historical civilizations that have no contact with each other. For example, many civilizations from both America, Africa and Eurasia went through very similar events immediately after developing agriculture. Therefore, it is reasonable to expect the same events to happen to any civilization that reaches the same state. Other historical events are harder to judge whether or not they fall into this category. In OTL, the Industrial Revolution was only invented in one part of the world, and gradually inspired or directly exported to every other nation since. However, there have been extensive studies on this subject, and the evidence suggests that any civilization would industrialize as soon as it had the ability to do so.
The Nuclear Age is more of an open question on whether or not it can be justified by Chaos Theory. Are nuclear weapons intrinsically tied to the level of advancement civilization reached in the 20th century? (Such that we expect any civilization equally advanced to do the same thing) Or is OTL history more of an aberration, such that humanity stumbled across a technology which, under normal circumstances, should have been developed much later?
It should be self-evident why Chaos Theory does not apply if the PoD is specifically about removing one of these events. If a PoD is made specifically to remove the Enlightenment, then clearly it would have to be placed relatively close to the Enlightenment in time. Because this is a relatively short period of time since the PoD, then it is expected for the timeline to be significantly divergent from OTL.
Also, bear in mind that this argument doesn't imply that these ATL events must happen at the same time as their OTL counterparts, only at the same level of development. If a timeline causes the Roman Empire to last to the modern day, for example, then it is very likely that the empire will become socially and technologically stagnate, and thus never reach the level of development such that the statistical patterns of OTL Europe would be expected.
In conclusion, a timeline that lasts thousands of years should plausibly expect to share some broad socio-political events with OTL in the long run (such as a Renaissance, Enlightenment, Industrial Revolution, etc.), as long as civilization advances at the same rate and enough time has passed for those statistical patterns to emerge. The timeline will slowly become more convergent as time goes on, until the modern day is dominated by liberal democracies just like in OTL. For a timeline with a PoD very close to the present day (within the last two hundred years), there is expected to be little to no convergent history at all. However, this is not a license to copy any specific entity from OTL (such as specific wars, nations, or individuals).
Chaos Theory shares many similarities with Plausibility Benchmarking, but there is a clear difference. Plausibility Benchmarking is a kind of Doylist approach, where the author deliberately chooses to use an OTLism in order to make the timeline more believable and immersive. Chaos Theory is more of a Watsonian approach, speculating if there is an intrinsic reason why certain events in history almost always happen in every timeline, including OTL. Unlike Plausibility Benchmarking, Chaos Theory doesn't assume that OTL history is a statistical norm, but instead assumes that certain broad events in OTL history are made more likely as time goes on.
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