Yeah. I read his popularisations too back in the day, and they were good. But I’m struggling to think of what he contributed to the discipline.
Wikipedia: Mario Pei.
He was an old school philologist, I see. And I have all the respect in the world for that. But I suspect that, if you’re not working on Romance historical linguistics, he won’t be on your radar, and even if you are, he won’t rank highly. Among his books listed in Wikipedia, only one looks to be a straight academic monograph (French Precursors of the Chanson de Roland, 1949), and one other a collection of papers.
No shame in that. Good solid philologists are necessary; I wish there were more of them. And I do popularisation of linguistics here, now, instead of academic work. It too is important work.
But “greatest linguist of the 20th century”… no.
, MA in Linguistics from BYU, 8 years working in research for language pedagogy.