Limits of Human Knowledge

Discussions on the philosophical foundations, assumptions, and implications of science, including the natural sciences.

Limits of Human Knowledge

Postby davidm on December 12th, 2019, 1:27 pm 

Apropos of this thread, today I stumbled upon the following:

The Uncomfortable Limits of Human Knowledge

From the linked article:

In 1859, astronomers determined that the orbit of Mercury was not behaving, over time, as Newtonian mechanics predicted. So another new planet (named Vulcan) was posited and its probable position calculated. Unlike the prediction of Neptune’s existence, this supposition did not pan out; rather, Newtonian mechanics was an incorrect theory in this context. Its conceptions of time, space, and simultaneity were simply wrong. A different scientific theory—Einstein’s theory of relativity—was required to later explain Mercury’s abnormal perihelion precession.


This is immediately followed by:
 
Examples of such later-overturned hypotheses litter scientific history across many fields: the spontaneous generation of life, bad air and the imbalance of four essential humors causing disease, embryos arising from homunculi, Pasteur’s theory of how vaccines work, Mesmer’s imponderable fluid that regulated human health, and so on.


I had written:

It is true that over time, theories are supplanted by better theories. But it is important to bear in mind that just because a theory is supplanted, it does not mean that the supplanted theory becomes invalid in its own domain of applicability. The best example of this is Newtonian physics. It was supplanted by relativity and quantum physics, but remains valid in its own domain of applicability. To chart the paths of spacecraft to other planets, all we need is Newton. Newton, in fact, works just fine in all workaday situations that do not involve high speeds or the microworld.


Now the author of the linked article does write: “Newtonian mechanics was an incorrect theory in this context,” meaning the context elucidated by relativity.

But that is just the point, to which I think the author gives insufficient weight: the “later-overturned hypotheses” that he mentions, have turned out to be valid in no context. But, as I said, Newtonian mechanics remains valid in its own domain of applicability — i.e., its own context. This is much different from spontaneous generation, bad air, and all the rest he cites.

And I suggest it is like this with evolutionary theory. Is it possible that future observations will lead to a new theory that, strictly, supplants our current evolutionary theory? Sure. But it does not follow from this that evolutionary theory will be completely discarded, anymore than Newton’s mechanics was completely discarded. Rather, Newtonian mechanics was found to be accurately descriptive, and hence useful, to a limit. I do not believe that there is any precedent for a theory as robustly supported as evolutionary theory, over such a long period of time, to be completely discarded — a very different state of affairs with, say, the theory of spontaneous generation, but perfectly in accord with the history of Newtonian mechanics.

Well, actually, admittedly, there is a precedent. Ptolemy’s geocentrism worked perfectly well for more than a thousand years, until it was completely overturned by Copernicus. To imagine that something similar will happen with evolutionary theory, though, takes a stretch of the imagination that is beyond me. But still, who knows?
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Re: Limits of Human Knowledge

Postby TheVat on December 12th, 2019, 1:48 pm 

Yes, I don't think ET will be replaced in the way that oxidation replaced phlogiston. There is no domain in which phlogiston theory still makes sense as a description of combustion or other oxidative processes. Changes in ET are more likely to add new layers rather than discard natural selection. Black moths will still make a comeback in Birmingham if they decide to go back to pre-50s coal burning.

I'm sure Boris Johnson has a plan!
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Re: Limits of Human Knowledge

Postby davidm on December 12th, 2019, 2:01 pm 

With respect to Ptolemy, though, it can and should be noted that his theory was not supported by robust and in-depth observational evidence (pre-Galileo), but only by superficial observation — such as positing that the earth is flat, because it looks to be so. No such superficiality is remotely comparable to evolution, which is backed by the fossil record, by the observation of selection and drift, by molecular biology, by population genetics, etc. For all of that to be wholly overturned, would strike me as a miracle on the order of Jesus rising from the dead.
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Re: Limits of Human Knowledge

Postby Forest_Dump on December 12th, 2019, 10:47 pm 

I think the history of science in Kuhn's classic on Scientific Revolutions pretty much covers most of this.
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Re: Limits of Human Knowledge

Postby Serpent on December 13th, 2019, 12:29 am 

davidm » December 12th, 2019, 12:27 pm wrote:It is true that over time, theories are supplanted by better theories. But it is important to bear in mind that just because a theory is supplanted, it does not mean that the supplanted theory becomes invalid in its own domain of applicability.

This is true, so long as the domain in which it operates continues to exist. But with each theory supplanted, the relevant domain shrinks - and sometimes disappears.

Is it possible that future observations will lead to a new theory that, strictly, supplants our current evolutionary theory?

There would be an awful lot to dispute and disprove. That's no longer a single theory based on an idea and a laboratory experiment - it's the result of extensive observation, recording, experimentation, testing and digging, by an awful lot of people over quite a long time - and with no hint of an alternative that comes even close to explaining a fraction of what evolution explains.

Well, actually, admittedly, there is a precedent. Ptolemy’s geocentrism worked perfectly well for more than a thousand years,

No, it didn't. It was accepted for all that time, because nobody questioned it - or if they did, they knew what was good for them and kept it to themselves.
until it was completely overturned by Copernicus.

who only meant to fix the obvious discrepancies in it, and when he realized what he'd actually done, refused to publish.

To imagine that something similar will happen with evolutionary theory, though, takes a stretch of the imagination that is beyond me. But still, who knows?

It depends on how far the regressive political movement succeeds.

What's published in science is not necessarily just about science.
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