I don’t of course use technical terms unnecessarily in daily conversation, but even aside from the fact that my knowledge of Greek would enable me to translate the term (in its original meaning, before cladistics transformed the meaning to make it theoretical rather than empirical), I’ve known the term since about my 18th birthday, when I got a wonderful book on animal life that has pages and pages of classifications at the back, of all the groups of animal life. I studied those pages over and over. So yes, I know the terms Chondrichthyes, Osteichthyes, Agnatha (“jawless fish” – though that term seems to be missing in the recent cladistics arrangements) etc. I used to be able to rattle off all the orders of mammals with ease – Hyracoidea, Pinnipedia, Lagomorpha, Dermoptera, Chiroptera, Pholidota, etc. Indeed, when I started at university on my science scholarship, I was wavering over what my major would be, and biology (with a focus on evolution) was one of the possibilities, I back then being a card-carrying, Bible-bashing worshipper of Carl Sagan.
And when I was a kid I was even more science-nerdy. I had sets of dinosaurs, the first bought for me by my grandparents when I was about 4-6 years old, and on their tails, embossed in plastic letters, were their names and how many feet long they were. I had all that information memorized, too, and read lots of books on prehistoric life. For a time I wanted to be a paleontologist, looking for dinosaur eggs in the Gobi Desert and so on. Later my passion was “outer space” (as it was often called back then), and I could have told you how many moons each planet had, which were the biggest known stars, how many trillion miles away Alpha Centauri was, and so on. I did one fifth or sixth grade project on quasars, and another on the Big Bang vs. Steady State notions of the origin of the universe. (Yeah, I know, that stuff was not on the science curriculum back then, but I was in a “gifted” class, and each month we had to do a project, so I picked projects of interest to me.) Before I finished high school I had the “molecules to man” narrative solidly in my head, from reading Sagan and Jastrow, two of the big scientist-science popularizers of the day. (With lots of details added from my mountain of books by Isaac Asimov.)
I did no such thing – for a lawyer, Puck, you’re a careless reader. What I did do was urge Harshman not to confuse non-specialists by mingling technical and lay vocabulary.
This is a forum where people of all walks of life participate, and the silent readers dwarf the number of vocal participants. Given that only a handful even among the regular participants are specialists in evolutionary classification like Harshman, and given that most of them are not even biologists, and that some are not scientists of any kind, and that the majority of the silent readers are very likely not biologists, layman’s language should be used unless technical language is necessary to make a point. And in layman’s language (I mean, those laymen educated enough to know the difference between a fish and a mammal, which probably applies to most lay readers of this site), whales are not “fish”. In fact, I bet that some members of this forum, in their precocious childhoods, enjoyed correcting less educated members of the benighted masses, maybe their aging grandmothers for example, telling them “whales aren’t fish, they’re mammals”.
So my point was not that cladistics is wrong or worthless, but that its language, if it leads to everyday conversations including non-biologists where someone says that whales are “fish”, is not appropriate for general conversation. Saying whales are descended from bony fish is fine; saying whales are fish muddies the waters for no good reason – unless desiring to impressing the rubes with one’s knowledge of cladistic classification counts as a good reason.