Guest post: What evidence was available
Originally a comment by Jim Baerg on Stuck in presentism.
It was only with Kepler’s elliptical orbits that a heliocentric model predicted planetary motions better than a geocentric model.
Galileo’s observation of Jupiter’s moons showed that there are at least some objects that definitely orbit something other than the earth. The phases of Venus are hard (impossible ?) to explain in a non-heliocentric model.
For a non-dogmatic thinker, it was really only the combination of all of those developments that would remove reasonable doubt about heliocentrism. Though the lack of observable parallax of stars bothered scientists until measurements became good enough to detect the parallax in the 19th century.
Similarly in the case of continental drift/plate tectonics. There was reasonable doubt until the 1960s. It was accumulated data better explained by plate tectonics that tipped earth scientists into general acceptance of plate tectonics.
Honest present day scientists can try to look at what evidence was available to their predecessors of a given time to judge what they might have believed under the circumstances.
How to apply similar considerations to ethical issues is another matter.
This reminds me of one of the favourite targets of creationist apologetics in their attempts to discredit science, Ptolemy’s epicycles. The argument goes something like:
1. Science will endorse anything in their search for an explanation of God’s work, no matter how obviously ridiculous it is.
2. As an example of this we have epicycles – the idea that planets orbited in perfect circles, but also orbited the larger orbital arc, which in combination make for a very curly path.
3. These things are obviously ridiculous!
4. Therefore science isn’t reliable.
This reasoning has multiple issues of course, but the one that reminded me of this niche argument in the first place was Jim Baerg’s first sentence. Epicycles were an improvement on what previously existed. They improved the ability to predict the path planets would trace in the sky, and what better test of a scientific model can there be but its predictive power relative to other purported explanations?
@Jim Baerg
You are totally right – Kopernikus said that his model was superior because it needed less epicycles (34 instead of 42 IIRC). I think there is another point often overlooked: Back then, science was still mainly Aristotelian. So moving objects tended to come to rest. It was easy to make an exception for celestial objects (because they might follow special rules), but if the earth was moving, why would it not stop?
A long time ago, I wrote a fictional conference talk from someone who argues why heliocentrism must be wrong:
https://scienceblogs.de/hier-wohnen-drachen/2010/08/28/eine-kritische-analyse-der-heliozentrischen-kosmologie/
It’s in German, but perhaps automatic translation may help, if someone is interested.
Plate tectonics was not accepted because Wegeners theory was obvious nonsense – he claimed (lacking better knowledge and desperately looking for a mechanism) that centrifugal forces were responsible for the movement of the plates. Of course people have noticed that the continents did fit together and agreed to that – but there was no known mechanism for moving continents, so there was no other choice but to call this an accident of history. It was only with the evidence for sea floor spreading that a mechanism was found and then plate tectonics was accepted very quickly.
With the acceleration in the advance of science, together with lengthening life expectancies, we see an increase in the frequency with which scientists survive to see, in old age, the resolution of the conundrums that they contributed to characterising in their youth. Fraunhofer died before Kirchhoff and Bunsen discovered that spectral lines were diagnostic of chemical elements; Maxwell died before Hertz could demonstrate radio waves, though he survived long enough to present his electromagnetic theory to Faraday. Darwin, though he lived to a good age, did not see the rediscovery of particulate inheritance, still less the modern synthesis. By contrast, in the modern era, John Bahcall had the satisfaction of witnessing the resolution of the solar neutrino puzzle through flavour mixing
The question of the evidence for plate tectonics triggered a classic tongue-in-cheek paper. A web search left me happily surprised to find that Wikipedia has coverage which has not even been attacked by deletionists, much less fallen victim to them.
So I got my first guest post. :)
Sonderval:
I guess I can quibble about Wegener’s continental drift not being plate tectonics.
IIRC he had some notion of the continents ploughing through the ocean basins with mountains forming on the leading edge, rather than being carried on plates moved by mantle convection as in plate tectonics. Less plausible, which helped keep the idea of moving continents from being accepted.
Alan Peakall:
Thanks for reminding me about “Continental Drip” ;^)