Like, just to begin with nearly all the facts he brings up are things Kuhn says. At no point does Kuhn give the reader the impression that there were only ever two competing astronomical models. What he says is that the Ptolemaic-Aristotelian model broke down starting with the Copernican suggestion of a Heliocentric universe. The range of theories the blogger lists fit perfectly in the Kuhnian model as stepping stones on the way to Keplerian-Newtonian astronomy. The blogger is right, for example that the Tychonic model was a powerful predictor, very popular and geocentric. But Brahe’s model is, according to Kuhn, nonetheless part of the transition away from Ptolemaic astronomy because 1) It places the Sun as the center of orbits of Mercury, Venus, Jupiter, Mars and Saturn and (therefore) demolishes the notion of crystalline spheres moving the planets (because such spheres would crash into each other and because he observed comets passing through them). Mathematically successful Brahe may have been, but his model leaves out all of the Aristotelian artifacts that made the Ptolemaic model so compelling. This is exactly what we expect in the midst of a paradigm shift—attempts to incorporate the new evidence into the old paradigm but simultaneously weakening the coherence of the old paradigm. The other geocentric + Earth spinning models the blogger mentions fit fine as well.
Kuhn like many historian treats Kepler as if he were just a minor amender of Copernicus and therefore not relevant
Like… what?! Kuhn spends half a chapter on Kepler. Quoting Kuhn now:
Each of these examples shows Kepler striving to adapt Copernicus’ overly Ptolemaic mathematical techniques to the Copernican vision of a sun-dominated universe, and it was by continuing this effort that Kepler finally resolved the problem of the planets, transforming Copernicus’ cumbersome system into a supremely simple and accurate technique for computing planetary position.
The blog author’s insistence on treating the seven theories he lists as equal and unrelated contestants just isn’t responsive to what Kuhn is talking about. That there was for 200 years more than two competing models is not at all reason to think there were more than two competing paradigms. There is no good reason to not call Kepler a Copernican even though he no long agreed with the techniques of Copernicus (100 years and Brahe’s measurements intervening). Kepler called himself a Copernican. And similarly there is no good reason not to see Brahe as trying to defend aspects of the old paradigm. His model is mathematically equivalent to the Copernican model, it consists of ret-coning the Ptolemaic model to make it fit observation for religious and philosophical reason. The blog doesn’t pay any attention to the extra-astronomical aspects of the revolution- these are the features that make up the paradigm. Any theory that ruins the Aristotelian cosmology is another chink in the old paradigm’s armor.
I could go on- but in short every other sentence in that post reads to me like a non-sequitur. Cartesians persisted in arguing for their model some fifty years after Newton died? So what? That’s neither here nor there.
I’ve read Kuhn and I didn’t see a problem with it. Care to elaborate?
Like, just to begin with nearly all the facts he brings up are things Kuhn says. At no point does Kuhn give the reader the impression that there were only ever two competing astronomical models. What he says is that the Ptolemaic-Aristotelian model broke down starting with the Copernican suggestion of a Heliocentric universe. The range of theories the blogger lists fit perfectly in the Kuhnian model as stepping stones on the way to Keplerian-Newtonian astronomy. The blogger is right, for example that the Tychonic model was a powerful predictor, very popular and geocentric. But Brahe’s model is, according to Kuhn, nonetheless part of the transition away from Ptolemaic astronomy because 1) It places the Sun as the center of orbits of Mercury, Venus, Jupiter, Mars and Saturn and (therefore) demolishes the notion of crystalline spheres moving the planets (because such spheres would crash into each other and because he observed comets passing through them). Mathematically successful Brahe may have been, but his model leaves out all of the Aristotelian artifacts that made the Ptolemaic model so compelling. This is exactly what we expect in the midst of a paradigm shift—attempts to incorporate the new evidence into the old paradigm but simultaneously weakening the coherence of the old paradigm. The other geocentric + Earth spinning models the blogger mentions fit fine as well.
Like… what?! Kuhn spends half a chapter on Kepler. Quoting Kuhn now:
The blog author’s insistence on treating the seven theories he lists as equal and unrelated contestants just isn’t responsive to what Kuhn is talking about. That there was for 200 years more than two competing models is not at all reason to think there were more than two competing paradigms. There is no good reason to not call Kepler a Copernican even though he no long agreed with the techniques of Copernicus (100 years and Brahe’s measurements intervening). Kepler called himself a Copernican. And similarly there is no good reason not to see Brahe as trying to defend aspects of the old paradigm. His model is mathematically equivalent to the Copernican model, it consists of ret-coning the Ptolemaic model to make it fit observation for religious and philosophical reason. The blog doesn’t pay any attention to the extra-astronomical aspects of the revolution- these are the features that make up the paradigm. Any theory that ruins the Aristotelian cosmology is another chink in the old paradigm’s armor.
I could go on- but in short every other sentence in that post reads to me like a non-sequitur. Cartesians persisted in arguing for their model some fifty years after Newton died? So what? That’s neither here nor there.
Thanks! That was very thorough.