Am I misunderstanding something? You seem to be defending a phylogenetic definition of “fish” as a reason why dolphins aren’t fish, but if you used a phylogenetic definition of “fish”, you’d still have dolphins be fish—that’s the first part of his argument.
I wonder to what degree the perspective comes from us generally not thinking about nonvertebrate animals. So the things that distinguish “phylogenetic fish” from them (like having craniums and vertebrae) are just considered “animal things”. And so instead, when defining fish we end up focusing on what distinguishes tetrapods and taking the negation of that. Sort of a categorical “tree rotation” if you will.
Another tree rotation is the human vs animal distinction. Humans are animals, but sometimes one uses “animal” to refer to nonhuman animals. I wonder if there’s some general things one could say about tree rotations. The human/animal distinction seems to have a different flavor to me than the fish/tetrapod distinction, though.
Something that also seems related is asking for an eggplant and expecting a fully-developed, non-rotting eggplant.
Such a category is called paraphyletic. It can be informationally useful if the excluded subgroup is far-divergent from the overarching group, such that it has gained characteristics not shared by the others, and lost characteristics otherwise shared. But the less divergence has taken place, the harder it is to justify a paraphyletic category. The category “reptile” (excluding birds) makes sense today, but it wouldn’t have made sense in the Jurassic period. The mammal/cetacean distinction is somewhere in the middle.
Animal/human is different because the evolutionary divergence is so recent that it’s difficult to justify the paraphyletic usage on biological grounds. Rather this is more of an ingroup/outgroup distinction, along the lines of βαρβαρος (“anybody who isn’t Greek”). If humans learned to communicate with e.g. crows, the shared language probably wouldn’t have a compact word for “non-human animal,” although it might have one for “non-human non-crow animal.”
Human intelligence counts as “gained characteristics not shared by the others”.
I think you’re thinking that it doesn’t count as a lot of divergence, but “a list of divergences with few items” doesn’t mean “not a lot of divergence”. Human intelligence has an effect on the environment and capabilities of humans that is equal or greater than the effect of the differences between birds and reptiles.
Am I misunderstanding something? You seem to be defending a phylogenetic definition of “fish” as a reason why dolphins aren’t fish, but if you used a phylogenetic definition of “fish”, you’d still have dolphins be fish—that’s the first part of his argument.
I wonder to what degree the perspective comes from us generally not thinking about nonvertebrate animals. So the things that distinguish “phylogenetic fish” from them (like having craniums and vertebrae) are just considered “animal things”. And so instead, when defining fish we end up focusing on what distinguishes tetrapods and taking the negation of that. Sort of a categorical “tree rotation” if you will.
Another tree rotation is the human vs animal distinction. Humans are animals, but sometimes one uses “animal” to refer to nonhuman animals. I wonder if there’s some general things one could say about tree rotations. The human/animal distinction seems to have a different flavor to me than the fish/tetrapod distinction, though.
Something that also seems related is asking for an eggplant and expecting a fully-developed, non-rotting eggplant.
Such a category is called paraphyletic. It can be informationally useful if the excluded subgroup is far-divergent from the overarching group, such that it has gained characteristics not shared by the others, and lost characteristics otherwise shared. But the less divergence has taken place, the harder it is to justify a paraphyletic category. The category “reptile” (excluding birds) makes sense today, but it wouldn’t have made sense in the Jurassic period. The mammal/cetacean distinction is somewhere in the middle.
Animal/human is different because the evolutionary divergence is so recent that it’s difficult to justify the paraphyletic usage on biological grounds. Rather this is more of an ingroup/outgroup distinction, along the lines of βαρβαρος (“anybody who isn’t Greek”). If humans learned to communicate with e.g. crows, the shared language probably wouldn’t have a compact word for “non-human animal,” although it might have one for “non-human non-crow animal.”
Human intelligence counts as “gained characteristics not shared by the others”.
I think you’re thinking that it doesn’t count as a lot of divergence, but “a list of divergences with few items” doesn’t mean “not a lot of divergence”. Human intelligence has an effect on the environment and capabilities of humans that is equal or greater than the effect of the differences between birds and reptiles.