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brainpushups said:I left out a key element which is that Popper's criterion hinges on falsifiability, not just testability. "X will evolve" is not a falsifiable claim.
One issue is that in evolution, the definition of evolution in specific predictions, as well as the specific nature of the predictions is harder to pin down. Usually, the claim of confirmation by prediction is made only AFTER the change is observed.
Using the definition of "change in allele frequencies over time" observation of evolution is trivial.
I think we can all agree that validated predictions of the future emergence of new species would be more impressive.
But even more interesting might be the ability to predict things like which species will evolve, which will move, and which will be extirpated in response to warming trends in specific regions.
If we really understood both evolution and global warming, shouldn't we be able to accurately predict which species have the capabilities to evolve fast enough to survive and which do not?
brainpushups said:Aside from those mentioned by Dr. Courtney, a historical example of a concept in physics which had no predictive power at the time of its introduction yet developed into a core principle is Ockam/Buridan's theory of impetus.
Perhaps another example, if you'll accept it, is that of phlogiston. Of course, this theory was replaced rather than augmented as in the case of impetus, but the concept of of phlogiston (which is not too dissimilar to that of oxidation – backwards really) was widely accepted, had no predictive power and helped catalyze the development of more fruitful theories.
EDIT: Oh, and the theory of atoms progressed in a similar vain.
Great points. Scientists often miss the distinction between descriptive and predictive until the descriptive theory gets replaced with a better model with real predictive power.
brainpushups said:Right, but in the case of medical research isn't there the risk of repeating studies on drugs (for example) that were shown to have no effect? It seems like having access to, and information about, null results could help streamline certain fields of research.
Of course. Null results should be published. But it seems to me that this requirement should be supported and enforced by the funding agencies rather than by external authorities. And in a business environment, why does one company who funded drug research care if another (competing) company wastes money on a dead end product?
Student100 said:Again, your examples aren't addressing the initial claim, that predictive power is somehow not a a defining element of science. The phlogiston hypothesis made predictions, thus it had predictive power, that just turned out to be wrong when experimentation tested those predictions.
I think you are confusing "predictive power" with falsifiability. Perhaps "predictive power" has not been defined as well as Popper defined "falsifiability." I do not see them as synonyms. For me, "predictive power" means able to reliably make CORRECT predictions of future events.
Falsifiability just means able to make predictions which are capable of being falsified in future experiments, whether or not they are.
So a theory that makes wrong predictions is falsifiable but has no predictive power.
A theory that makes right predictions is falsifiable and has predictive power.