It’s a very interesting and controversial claim that heliocentrists were not really any more justified, epistemically, than the geocentrists. I will have to think more about that.
I feel like it might benefit from some additional clarification, because of the trap Asimov points at here:
John, when people thought the earth was flat, they were wrong. When people thought the earth was spherical, they were wrong. But if you think that thinking the earth is spherical is just as wrong as thinking the earth is flat, then your view is wronger than both of them put together.
It seems to me like there are about six important advances relevant to astronomical phenomena:
Periodic, predictable motion
Circular motion
Elliptical motion
Inverse square law
No privileged reference frame
The metric tensor / general relativity
Most of those are approximations to later principles--2 is an approximation to 3, which is an exact solution to 4, but 4 is only an approximation to 6. (This also isn’t the end of knowledge; I haven’t included things here that a working cosmologist would, let alone a future physicist.)
My view is that the geocentrists and heliocentrists (as factions) are both stuck in having just 1+2, and openly contradicting 5. That says the interesting questions are: how did Kepler come up with 3, how did Newton come up with 4, and how did Einstein come up with 5 and 6?
Even there the answer might sometimes be luck, as opposed to good thinking skill. One could imagine a version of Kepler who thought ellipses were theologically significant, and tried to apply them to everything, and discovered that they happened to work for astronomy. This doesn’t seem like a strategy worth stealing, whereas the strategy of “get good data, and try lots of functions on the data” does seem like a good strategy worth stealing. (And we can see Kepler’s mistake of not doing the Occamian thing and recognize that it was a mistake.)
This view looks like it has two weaknesses. First, the list of six things that I picked. The scale of the universe didn’t make the list, but might seem comparably important to 5. The position of the center of mass of the solar system also didn’t make the list, because ‘center of mass’ isn’t an interesting concept until you have conservation of momentum. (Since Aristarchus people have known the sun was bigger than the Earth, but until you understood gravitation, why would that be inconsistent with the sun moving around the Earth?) But I don’t think there’s a thing that could be added to the list such that the heliocentrists have clearly made an advance that the others haven’t.
Second, the claim that heliocentrists and geocentrists both openly contradict 5. In retrospect, many present heliocentrism as giving up on Earth’s privileged position, which is one of the inferential steps towards thinking that there’s no privileged position. But it’s not clear to me that this is the right way to view things; in particular, it seems important to distinguish the statements “the Earth isn’t special” from “the Sun is more special than the Earth.” My second-hand understanding is that Copernicus wouldn’t endorse the Copernican Principle. (One could point to Bruno or Galileo or so on as pointing towards this advance, but they don’t get credit for empirically discriminating between possibilities, much like Democritus doesn’t get credit for proving that matter is made of atoms.)
It’s worth noting that Kepler had the intuition that the motions of the planets ought to be produced by distinct lines of force adding up to regular curves—much as Galileo points out that constant acceleration is enough to cause mundane objects to fall in parabolic curves. But he didn’t quite have enough math to formalize this persuasively—that had to wait until Newton.
Likewise, ellipses are more difficult to work with than circles, until something like Cartesian analytic geometry lets you formalize them simply without any direct reference to conic sections.
It’s a very interesting and controversial claim that heliocentrists were not really any more justified, epistemically, than the geocentrists. I will have to think more about that.
I feel like it might benefit from some additional clarification, because of the trap Asimov points at here:
It seems to me like there are about six important advances relevant to astronomical phenomena:
Periodic, predictable motion
Circular motion
Elliptical motion
Inverse square law
No privileged reference frame
The metric tensor / general relativity
Most of those are approximations to later principles--2 is an approximation to 3, which is an exact solution to 4, but 4 is only an approximation to 6. (This also isn’t the end of knowledge; I haven’t included things here that a working cosmologist would, let alone a future physicist.)
My view is that the geocentrists and heliocentrists (as factions) are both stuck in having just 1+2, and openly contradicting 5. That says the interesting questions are: how did Kepler come up with 3, how did Newton come up with 4, and how did Einstein come up with 5 and 6?
Even there the answer might sometimes be luck, as opposed to good thinking skill. One could imagine a version of Kepler who thought ellipses were theologically significant, and tried to apply them to everything, and discovered that they happened to work for astronomy. This doesn’t seem like a strategy worth stealing, whereas the strategy of “get good data, and try lots of functions on the data” does seem like a good strategy worth stealing. (And we can see Kepler’s mistake of not doing the Occamian thing and recognize that it was a mistake.)
This view looks like it has two weaknesses. First, the list of six things that I picked. The scale of the universe didn’t make the list, but might seem comparably important to 5. The position of the center of mass of the solar system also didn’t make the list, because ‘center of mass’ isn’t an interesting concept until you have conservation of momentum. (Since Aristarchus people have known the sun was bigger than the Earth, but until you understood gravitation, why would that be inconsistent with the sun moving around the Earth?) But I don’t think there’s a thing that could be added to the list such that the heliocentrists have clearly made an advance that the others haven’t.
Second, the claim that heliocentrists and geocentrists both openly contradict 5. In retrospect, many present heliocentrism as giving up on Earth’s privileged position, which is one of the inferential steps towards thinking that there’s no privileged position. But it’s not clear to me that this is the right way to view things; in particular, it seems important to distinguish the statements “the Earth isn’t special” from “the Sun is more special than the Earth.” My second-hand understanding is that Copernicus wouldn’t endorse the Copernican Principle. (One could point to Bruno or Galileo or so on as pointing towards this advance, but they don’t get credit for empirically discriminating between possibilities, much like Democritus doesn’t get credit for proving that matter is made of atoms.)
It’s worth noting that Kepler had the intuition that the motions of the planets ought to be produced by distinct lines of force adding up to regular curves—much as Galileo points out that constant acceleration is enough to cause mundane objects to fall in parabolic curves. But he didn’t quite have enough math to formalize this persuasively—that had to wait until Newton.
Likewise, ellipses are more difficult to work with than circles, until something like Cartesian analytic geometry lets you formalize them simply without any direct reference to conic sections.
Newton has 5 for everything except the weird speed of light anomaly that Einstein exploited.