To be sure, convergent evolution is a thing, such that sometimes we might want short codewords that point to the cluster-structure-produced-by-convergent-evolution rather than the conditional-independence-structure-produced-by-connectedness-in-phylogenetic-spaceātrees, and possibly crabs, are a case in point. But itās important to notice the differenceāto see through to the inferences your concepts are buying youāand what gets lost when you try to reason in a domain where your concept falls apart.
Zack, what are you claiming is lost? The straw-anti-phylogenist who headlines your post says:
Choosing to define categories around evolutionary relatedness rather than macroscopic human-relevant features seems like an arbitrary Ʀsthetic whim.
This seems genuinely straw, relative to the simple position: ā[Swimming-adapted animals] is a useful, joint-carving concept. [The clade containing all swimmers, minus the clade of landlubbers] is a useful, joint-carving concept. Sometimes one or the other is most suitable. If someone tells me Iām supposed to use one or the other, when the alternative is more suitable, based on some simplistic policy of using words that are joint-carving in one way but not the other (rather than arguing suitability), theyāre just being silly.ā Each of these concepts compresses cluster-structure in thingspace. You canāt explain why dolphins and fish both propel themselves by undulating in a certain way by reference to phylogeny, you have to talk about adaptation to the vorticial behavior of water. You canāt explain why dolphins breath air by reference to swimming-adaptedness, you have to talk about phylogenetic relatedness to air-breathers.
Ditto.
This is addressed as a side-note in the paragraph
Zack, what are you claiming is lost? The straw-anti-phylogenist who headlines your post says:
This seems genuinely straw, relative to the simple position: ā[Swimming-adapted animals] is a useful, joint-carving concept. [The clade containing all swimmers, minus the clade of landlubbers] is a useful, joint-carving concept. Sometimes one or the other is most suitable. If someone tells me Iām supposed to use one or the other, when the alternative is more suitable, based on some simplistic policy of using words that are joint-carving in one way but not the other (rather than arguing suitability), theyāre just being silly.ā Each of these concepts compresses cluster-structure in thingspace. You canāt explain why dolphins and fish both propel themselves by undulating in a certain way by reference to phylogeny, you have to talk about adaptation to the vorticial behavior of water. You canāt explain why dolphins breath air by reference to swimming-adaptedness, you have to talk about phylogenetic relatedness to air-breathers.
A potential crux:
I would also say:
but Iām not sure youād admit that, since the niche shows up in the causal graph in at best a cryptic way.