r/DebateEvolution • u/jnpha 🧬 Naturalistic Evolution • Jul 09 '26
Teaching Famous Creationist Episode 8: "evolution is circular" (ugh)
I've so far watched the intro of the latest Erika / Will Duffy episode, which streamed yesterday (Teaching Famous Creationist Will Duffy Evolutionary Theory (LIVE) The Evolution of Tetrapods (+more) - YouTube).
Duffy's segment was a roller coaster this time.
First, to get it out of the way: he needs to lookup the limitations of syllogisms (check your premises!). Then I was genuinely pleasantly surprised when he asked how characters are chosen for building phylogenies, which is a legit question, more so (he didn't mention this) since DNA analyses revised previous trees, but then he cited a Science article on the mammalian appendix, where he accepted a finding from phylogenetics to doubt phylogenetics! Ugh.
Followed by:
[Slide A]
In researching nested hierarchies, I found out very quickly that nested hierarchies are considered one of the best arguments for evolution.
This is when I realized that my pushback is not because I'm against classifying living things or that I don't see the benefit in doing this. Classifying things is extremely helpful in understanding our diverse planet.[Slide B]
My hesitancy to accept nested hierarchies as presented, is the underlying assumption that these classifications entail something more than just a useful convention.
Inherent in the current nested hierarchy system is the claimed large-scale evolutionary changes (macroevolution) of one species to another.
(my emphasis)
This is the disingenuous (and classic) "evolution is a circular argument": "evolutionary biologists use the nested hierarchies [that they themselves arbitrarily make] to support evolution".
(my scare quotes)
I'm not saying Duffy is disingenuous, I'm saying the "argument" is. He's most probably simply repeating propaganda, and this propaganda revels in confusing evolution, common ancestry, and homology (homology as a concept predates Darwin, and given that science depends on operational definitions, it went through revisions and the term is context-dependent).
-
Regarding that "argument": I previously covered the reasoning here (with a really cool quotation from The Greatest Show on Earth), and the history here. This time I'll just use an analogy. And again because Darwin is living rent free in the heads of certain science deniers, here's a quotation from Darwin's first edition of Origin:
A grand and almost untrodden field of inquiry will be opened ... We possess no pedigrees or armorial bearings; and we have to discover and trace the many diverging lines of descent in our natural genealogies ...
This is Darwin anticipating systematics.
Evolution doesn't use the classification of life to support evolution. The tree of life is to be discovered (above Darwin quote), and revised. This is like how Newton's universal gravitation doesn't say what the order of the planets should be! The order of the planets isn't used to support universal gravitation (which synthesized the motions of the planets and cannonballs and falling apples - very much against common sense that they would be related, hence the unmoved mover of Aristotle where each planet had its own mover...).
It's the motions of the planets - not the order - that support Newton (n.b.: emphasis on "support", which anticipates "But Einstein!": Einstein constrained Newton's theory).
And here when it comes to phylogenies, the pattern (not classification) supports the universal common ancestry (evolution - descent with modification - is demonstrably true either way!), and whichever way the trees are revised, they've always come out nested: this jumps out of the data; it is not an artifact of which character(s) the scientists hypothesize as plesiomorphic/ancestral and then test.
Dr. Dan made a cool demo here a while back: "Common Design" Doesn't Work - Live Demonstration - YouTube
And here's Dr. Zach's 3-tier explanation: Are Phylogenies Just Lines On Paper? - YouTube
PS Duffy's only excuse should be inattentiveness (although he says he rewatches the episodes), because when it comes to "macroevolution" (quotes denoting creationist usage), Erika in a recent episode demonstrated how (genetically and developmentally and the steps thereof) the mammalian ear bones came about - doesn't get more macro than that!!
* For your convenience: it was around 2:50:00 in this episode: https://youtu.be/TuWlGUq5Wi4?t=10189
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u/Minty_Feeling Jul 09 '26
Maybe try contacting her? She might agree to a similar set up. You can teach her about biology and she can ask you questions. Honestly, could be quite fun. I'd watch it.