The Core

George Orwell didn't account for human fallibility.

No but everyone who watched the fall of the Soviet Union, East Germany and the Stasi in particular, should account for it.

But of course, there's always the crowd that says "This time it's different." And the scary part is that every once in a while, those people are right.

Sure.

Wrong: in the age of the train, people will stop using horses.
Right: the car changes everything; people will stop using horses.

Wrong: By the 1980s, India will experience widespread famine, as it always has during population growth and bad ag cycles (Paul Erlich).
Right: No, this time people will figure out how to avoid it. I forget the name of Erlich's opponent in these debates. But basically he was an outlier who said that world famine would decrease, not increase in the 1980s and 1990s, because this time it's different. And he was right.

I think there are many more cases like this, but we tend to forget them due to a hindsight bias. In other words, when someone says "This time it's different" and that person is right, we forget 50 years later that this was not the dominant opinion. The dominant opinion was that X would never change.

I think the classic example would be the French Revolution. France had had revolt after revolt. Huge uprisings that swept across the country throughout the years, some even well-backed by elements in power. But as Dickens said in Tale of Two Cities, it had become inconceivable that a society where the executioner wore a powdered wig would not outlast the stars.

But when the Revolution broke out, legend has it that the king asked if it was a revolt, and an advisor said, "No sire, it is a revolution." Might be apocryphal. But the person who said "this time it's different" was right.

Same with Martin Luther. In 1453 (if memory serves), Jan Hus was put to death at the decision of the Council of Constance for very similar critiques of the church. There was Wyclif, there were many. Most people would have said that the Mother Church was eternal. But, when Luther stood before the Imperial Diet and refused to recant, there were those who said "This time is different," and they were right.

For the area that I study, after the Reformation, people widely assumed that the Reformation was a "fad." They referred to it as "last week's religion" (la religion de huit jours). They hid their prohibited books and waited until they would be allowed again. They wrote wills with provisions for how many masses they wanted said "if the times change." But someone said "This time it's different," and that person was right. Catholics were not allowed to have a church in Geneva for almost 300 years.

Again, we tend to forget these things because of the way history is taught. Things that last take on a air of inevitability. But in all those cases, there was at first a small number of people saying "This time it's different," and in those small, but often massively noteworthy cases, they were right.

Great stuff Ergo.  We shouldn't be complacent with our assumptions.

It's not so much a question of assumptions as perspective.

In history, there is a perspectival bias called "presentism." The short version is that a presentist approach to history starts with the question "How did we get here?"

Reasonable question, but it creates lots of follow-on problems for someone who wants to understand 1) the past and 2) how we actually did get here.

The main problem with a presentist perspective is that it encourages you to study the Middle Ages entirely in terms of which elements were stepping stones to where we are now. This has some follow-on effects too.

1. Things that were of the utmost importance to a medieval person can be get completely ignored, because they don't fit into a nice narrative of how we got here.

2. Things that seem like precursors get labelled as precursors whether they are or not.

A classic example is Copernicus and Kepler. People often present Copernicus as having finally looked at the way the solar system functions based on data and having gotten rid of all those "epicycles" required to make the Ptolemaic model work. But actually, Copernicus reduced the size of the major epicycle, but did not reduce the number appreciably. More important, there was no observational proof that Copernicus was right for half a century. The driver was as much increased interest in Platonism and the desire to put the sun at the center than a model of the universe that conformed better to observation.

Same with Kepler. His Platonism has two conflicting nudges - on the one hand, a circle is a perfect form, but on the other hand, a model with a single ellipse seems more perfect than a model that requires dozens of circles. That's the nudge that set him looking for the mathematics that would result in the theory of elliptical orbits.

But in a "whig" or "presentist" presentation, they become heroes of modern science who allowed observation of things as they actually are triumph over slavish adherence to Aristotle and Ptolemy.

Similar with Descartes. He is typically taught in the university in such a way that his science is barely ever mentioned, because in fact his science does not fit into the the "march of history" from a presentist perspective very well. He believed in a plenum (no empty space), a set of vortices that pulled heavier matter in (planets) and lots of other ideas that appear daft to us. They were, however, highly influential at the time and most scientists were deeply influenced by Descartes.

Meanwhile, his Meditations on First Philosophy ("I think, therefore I am") had a big influence on later thinkers, especially Kant. So we end up with a history of Philosophy that tends to go Plato to Aristotle to Descartes to Kant. But in fact, Descartes was not continuing Aristotle as a means to make a bridge to Kant (presentist view). Descartes obviously knew nothing of Kant. The dominant trend at the time was philosophical skepticism and Descartes was trying to find a rational response to skepticism that would enable philosophy and science to make assertions.

All of that to say that when we have presentist perspective, we tend to push aside the science of Descartes and just not study it at all, but pull the science of Kepler and Copernicus into the methodical march toward the present.

We forget that Copernicus is one of several people to have theories of the solar system and we make his theory seem obvious and inevitable. We forget that people were saying "Just another flawed theory" and others were saying "this time it's different"

We also get abysmal, terrible, awful and ridiculous televsion shows like Neil de Grasse Tyson's treatment of Giordano Bruno

This is an oversimplification of your points but basically it all fits with that saying falsely attributed to Mark Twain.

“History doesn't repeat itself but it often rhymes,”

Yet it is another attempt to boil many variables into an easy to digest truth.