The Great Chain of Being

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Originally posted by Andya Primanda:
OK, I want to make the debate straight. My opposition states that progress can be defined in neural complexity and stages of consciousness. He considers that his definition is the position of many scientists.

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I'm new to this forum, although I used to participate in Percy's old yahoo! club...The "position of many scientists" is just hand waving unless he names some. And since you can't get two scientists to agree on what the hell "consciousness" means, this guy really can't argue for any sort of consensus based on "stages of consciousness".There's actually no particular expertise needed to answer this. There's plenty of evidence that evolution can result in lower neural complexity as well as higher. If a free swimming/moving organism evolves into a filter feeder, say (e.g., the sea squirt), or a parasite (e.g. tapeworm), you don't need a complex brain. The sea squirt is famous for eating its own brain, in fact - after passing through a brief free swimming developmental phase, it takes root in a nice spot, and absorbs its own brain - won't be needing that anymore! (This has been compared to the tenure process, by the way).The fact that things are more complex, "on average", now than at the beginning of life can be fully explained assuming a random walk of increasing or descreasing complexity. Since you start at zero, you can only end up higher.Imagine every new species is equally likely to be either more or less "complex" or "conscious" than its parent species. No direction here, right? Just random. Still, the highest "complexity" or "conscious" organism will tend to be more complex over time, even though there is no direction or systematic change. Indeed, the vast majority of life is and always has been bacterial, hardly a sign of an inherent drive towards greater "consciousness"!So, if you want to argue that evolution is fundamentally progressive, you have to do more than say "look, humans have big brains, trilobites didn't".Now, I think it's possible that there might be a statistical bias towards complexity along some measures. But even this wouldn't show a "great chain of being". What philosophical conclusions would one draw from a statistical walk through a continuum of complexity?

Oh, S.J. Gould (R.I.P.) develops many of these ideas in his book "Full House". He covers it in several essays as well, but I couldn't give you references on those without a bit of work.

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Originally posted by Quetzal:
WRT your post: in other words, the rebuttal to Andya's opponent's position on intelligence is the same (roughly) as the rebuttal to the old Escala naturae - there's no evidence that nature is required to tend toward increasing perfection or complexity. It can, in fact, go either way. Did I catch it right?

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Yeah, what you said!And another point: Everything's been evolving for the same amount of time, and 99% of it is bacteria, fungi, plants, and protists. To characterize evolution in terms of "neural complexity" when nearly all life lacks a nervous system seems pretty misguided.------------------
"Colorless green ideas sleep furiously." - Chomsky