Is Evolutionary Theory a Fallacy?

[Rumraket (Mikkel R.)]

@Don_Mc

That’s all well stated, and I agree. As I mentioned earlier the FoC is an informal fallacy, in that an inference from parts to whole is neither necessarily true nor necessarily false; it depends on the composition of the structure in question. But if someone says the whole has property x because the parts have property x, they are guilty of fallacious reasoning.

I think you should say they could be guilty of fallacious reasoning, not that they are(as in necessarily).

After all it could be true that the reason why the whole has property x is because the parts have property x. I return to the red lego bricks analogy. Why is the structure made of all the lego bricks red? Because all it’s individual parts are red. Why is the structure made of plastic? Because all the parts are made of plastic.

So one does not necessarily commit a fallacy by doing compositional reasoning. There are cases where such inferences fail, and cases where it doesn’t. For that reason I don’t see much value in erecting the fallacy of composition against a hypothetical case of flagellum evolution. There would have to be emergent attributes that would prevent combinations of parts from being selectable.

Suppose we treat the flagellum as being made of the components A, B, C, and D. When A, B, C, and D, are assembled in some particular order, A-B-C-D, we have a flagellum, and the flagellum has a selectable function. Suppose also it is true that the components individually have evolvable functions that natural selection can explain, such that each component alone has a selectable function. As in A alone has a selectable function, B alone has a selectable function, etc.

So we could say natural selection can explain A alone, B alone, C alone, and D alone. However, and here I think the fallacy could potentially occur, because natural selection can explain any one component alone, therefore natural selection explains the gradual elaboration of the structure such that it first explains A, then it explains A-B, then it explains A-B-C, and finally A-B-C-D.
This could be a faulty inference if, in fact, either A-B, or A-B-C together doesn’t have a selectable function. That when combined into intermediate structures hypothetically ancestral to the flagellum, they are functionless.

But I don’t think the real evolutionary inference is that because A, B, C, and D individually can be explained by natural selection, then A-B-C-D can be explained by natural selection. I get that you found what appears to be an example of an article making a statement to this effect, but I don’t think any case for the flagellum’s evolution requires that sort of reasoning.

Rather, the evolutionary inference is that because natural selection can explain A, A-B, A-B-C, and A-B-C-D, then natural selection can explain the incremental evolution of A-B-C-D through the selectable intermediates. Now that of course does depend on it being true that A, A-B, and A-B-C have selectable functions natural selection can explain.
When it comes to the flagellum, I think we have good evidence that is true. We know of simpler systems made of partial structures that are plausible as pre-flagellar intermediates, that have selectable functions. So I just don’t think we have reason to think there are any unforeseen emergent properties that would prevent the evolution of the flagellum through simpler intermediates. For that reason I don’t think we have any good reason to think the real argument for the flagellum’s evolution actually commits the fallacy of composition.

@Don_Mc

It seems to me that for the inference to fail to a composition fallacy, that if natural selection can explain each step in the evolution of the flagellum then natural selection explain the entire flagellum, the entire flagellum would have to exhibit novel emergent properties of some sort that makes natural selection unable to act on it at some point. Your thoughts?

Honestly I didn’t quite follow all that.

Sorry that was badly phrased. I should have said the following:
It seems to me that for the inference to fail to a composition fallacy—that if natural selection can explain each component individually of the flagellum then natural selection explains the evolution of the entire flagellum—then intermediate stages in it’s evolution made of fewer components would have to exhibit novel emergent properties as a byproduct of some sort that makes natural selection unable to act on those intermediate structures.

@Don_Mc

I start with the idea of natural selection acting on various structures and then question whether natural selection can be reasonably expected to perform the additional feat of assembling those structures to produce a new functionally complex system. The difference is subtle, but one implication is that I’m not trying to show that evolution of these sorts of systems is impossible.

I’m not sure I get what you’re saying. I mean it is a fact that natural selection occurs, that structures of various sorts suffer mutations of various types, and that these alter their functions and properties in different ways when they occur, and that these changes are subject to natural selection. With this in mind, I just don’t see why the flagellum should be thought of as an intrinsically implausible outcome of such a history of such changes? Wouldn’t any sufficiently long history of mutations subject to natural selection, or even a history that involved occasional design-interventions, look incredibly unlikely after the fact?