Rachell Powell

speaker

762 appearances 1 recordings 1 series first heard Jan 2026 last heard 26 Jan

Rachell Powell’s voice in public audio — every appearance, attributed to the second.

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Recordings per month over the last 12 months — 1 in all, peaking in Jan 2026 with 1.

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Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas · 342 | Rachell Powell on Evolutionary Convergence, Morality, and Mind · 26 Jan 2026 podcast

So the big problem is there are no globally optimal traits, meaning traits that are always going to be fit, always going to be optimal.

So as a result, you just don't get any specific laws falling out of the principle of natural selection that's not gonna tell you what evolves.

And that seems like a really interesting fact, but that's a fundamental reason or one of the fundamental reasons why the history of life is not amenable to the same kinds of projections or predictability.

Or at least we just don't have any evidence yet that it is.

Although the convergence people are going to come and say, well, maybe there is –

Maybe there is some evidence.

So let me just now just give you the Gouldian take on contingency, and then I'll tell you the convergence response and sort of where things stand now, and then we can just talk more freely.

Stephen Jay Gould, a paleontologist and evolutionist, he came along in the late 80s, early 90s, and he was sort of first really robustly articulating this notion of there being contingency in the history of life, and he was really pushing back against

the sort of progressivist narratives that people have tended to imbue to the evolutionary process.

Progressivist, I mean, in common cultures, you see the quadrupedal creature, then the knuckle-walking creature, then the creature walking upright, and it looks like a single linear trajectory of progress.

We know that all of that is false.

That's not the way we think about evolution.

And so Stephen Jay Gould was very much keyed into that, and his contingency thesis was very much aimed at kind of demolishing the idea that there are these kind of progressive forces in evolution.

And by the way, the assumptions of progress and evolution, unlike in physics, I think that they have infiltrated thinking about biology very profoundly, and probably even in 20th century thinking about SETI.

But anyhow, this is what Gould said, and it's really a beautiful argument.

I'll tell you what I think the state of it is, and then what the responses are, why the responses are not adequate, and where we are now.

Gould basically said,

Let's do a thought experiment.

So in physics, right, thought experiments have played interesting roles.

In biology, no, not that I know of, right, which is interesting in itself.

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