My update is further in the direction that Jacob’s post The Copernican Revolution from the Inside argues for, which is that if two different people had different theories at the time, I do not anticipate the disagreement being able to be “clearly resolvable” at all, and do expect for it to involve a great number of judgment calls, in large part dependent on one’s “philosophy” of how to make those calls in this domain.
… there is rarely a single experiment that one paradigm fails and another passes. Rather, there are dozens of experiments. One paradigm does better on some, the other paradigm does better on others, and everyone argues over which ones should or shouldn’t count.
For example, one might try to test the Copernican vs. Ptolemaic worldviews by observing the parallax of the fixed stars over the course of a year. Copernicus predicts it should be visible; Ptolemy predicts it shouldn’t be. It isn’t, which means either the Earth is fixed and unmoving, or the stars are unutterably unimaginably immensely impossibly far away. Nobody expected the stars to be that far away, so advantage Ptolemy. Meanwhile, the Copernicans posit far-off stars in order to save their paradigm. What looked like a test to select one paradigm or the other has turned into a wedge pushing the two paradigms even further apart.
What looks like a decisive victory to one side may look like random noise to another. Did you know weird technologically advanced artifacts are sometimes found encased in rocks that our current understanding of geology says are millions of years old? Creationists have no trouble explaining those – the rocks are much younger, and the artifacts were probably planted by nephilim. Evolutionists have no idea how to explain those, and default to things like “the artifacts are hoaxes” or “the miners were really careless and a screw slipped from their pocket into the rock vein while they were mining”. I’m an evolutionist and I agree the artifacts are probably hoaxes or mistakes, even when there is no particular evidence that they are. Meanwhile, probably creationists say that some fossil or other incompatible with creationism is a hoax or a mistake. But that means the “find something predicted by one paradigm but not the other, and then the failed theory comes crashing down” oversimplification doesn’t work. Find something predicted by one paradigm but not the other, and often the proponents of the disadvantaged paradigm can – and should – just shrug and say “whatever”.
In 1870, flat-earther Samuel Rowbotham performed a series of experiments to show the Earth could not be a globe. In the most famous, he placed several flags miles apart along a perfectly straight canal. Then he looked through a telescope and was able to see all of them in a row, even though the furthest should have been hidden by the Earth’s curvature. Having done so, he concluded the Earth was flat, and the spherical-earth paradigm debunked. Alfred Wallace (more famous for pre-empting Darwin on evolution) took up the challenge, and showed that the bending of light rays by atmospheric refraction explained Rowbotham’s result. It turns out that light rays curve downward at a rate equal to the curvature of the Earth’s surface! Luckily for Wallace, refraction was already a known phenomenon; if not, it would have been the same kind of wedge-between-paradigms as the Copernicans having to change the distance to the fixed stars.
It is all nice and well to say “Sure, it looks like your paradigm is right, but once we adjust for this new idea about the distance to the stars / the refraction of light, the evidence actually supports my paradigm”. But the supporters of old paradigms can do that too! The Ptolemaics are rightly mocked for adding epicycle after epicycle until their system gave the right result. But to a hostile observer, positing refraction effects that exactly counterbalance the curvature of the Earth sure looks like adding epicycles. At some point a new paradigm will win out, and its “epicycles” will look like perfectly reasonable adjustments for reality’s surprising amount of detail. And the old paradigm will lose, and its “epicycles” will look like obvious kludges to cover up that it never really worked. Before that happens…well, good luck.
Related, from Scott Alexander’s review of The Structure of Scientific Revolutions:
Yeah yeah! I’ve heard this before and all. Somehow I felt it be more part of me this week.