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Is The Limited View of Evolution Scientific?

continued from Is Evolutionary Theory Scientific?

First, I'll consider the more limited meaning of evolutionary theory that doesn't involve claims about the past. To keep it simple, I'll consider this theory as just involving something like the following: "The fittest members of a species survive to pass their genes on to the next generation, so traits that make an individual more likely to survive to produce offspring will be more likely to appear in future generations."

This theory is of course falsifiable to a certain extent - if the genetic assumptions included in it weren't right, experiments could show that to be the case. If, for example, the offspring of two individuals did not have a genetic makeup derived from theirs, that particular aspect of the theory would be shown false.

But a theory needs to be generally falsifiable, not just partially falsifiable, to count as scientific. Otherwise all sorts of whacky, partially-falsifiable theories would count as scientific. So the question is whether or not the limited evolutionary theory as a whole is falsifiable.

The limited evolutionary theory does make future predictions: the fittest members of a any particular species will, in general, pass on their genes/traits to future generations more than less fit members will. This seems at least possibly falsifiable - you could observe a species over time and see that the genes/traits passed along were not generally from its fittest members. This would show that this particular formulation of evolutionary theory didn't hold up.

But then again, this formulation of the theory almost seems like a tautology. Don't we simply define "fittest members of a species" as those who do survive to pass on their genes/traits? That means that whatever members generally don't pass on their genes are by definition not the fittest. But this would mean the theory was generally not falsifiable.

We could try to save the theory by using some other definition of "fittest" - maybe as "members of a species most likely to live long, healthy lives". But that won't necessarily fit with the facts - genes are passed on by members of a species who have the most offspring (that also have offspring that have offspring...). This means that any genes not affecting individuals until after the normal child-bearing period can be passed along even if they are harmful later on.

Examples of this in humans are genetic disorders like Huntington's disease that are devastating later in life but generally don't affect their ability to father/mother offspring. Others are possible - even disorders that would increase an individual's likelihood to pass on genes but making him or her less fit according to the "members of a species most likely to live long, healthy lives" definition. There could be a disorder that made an individual extremely fertile, and thus more likely to have offspring, but that also made that individual die early (as long as it wasn't too early to produce a good number of offspring).

As long as we consider the situation I just mentioned as being possible (I see no reason to think that it isn't), then we have to either modify our theory of evolution or give up this new definition of fitness. But unless we come up with some definition of fitness other than the one just mentioned, we are back to the first, which risks making our theory unfalsifiable.

Conclusions: The limited evolutionary theory is quite possibly generally non-falsifiable and thus non-scientific. But I'm sure there's more to be said for each side of the debate, so I'm not prepared to conclude that it is not falsifiable for sure. But its falsifiability is certainly questionable, at best.

Next: The more comprehensive view of the theory of evolution.

Is Evolutionary Theory Scientific?
Is The Limited View of Evolution Scientific?
Man Living with Dinosaurs?
Is the More Comprehensive View of Evolution Scientific?


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