We present evidence that mainstream Anglophone philosophy is insular in the sense that participants in this academic tradition tend mostly to cite or interact with other participants in this academic tradition, while having little academic interaction with philosophers writing in other languages. Among our evidence: In a sample of articles from elite Anglophone philosophy journals, 97% of citations are citations of work originally written in English; 96% of members of editorial boards of elite Anglophone philosophy journals are housed in majority-Anglophone (...) countries; and only one of the 100 most-cited recent authors in the Stanford Encyclopedia of Philosophy spent most of his career in non-Anglophone countries writing primarily in a language other than English. In contrast, philosophy articles published in elite Chinese-language and Spanish-language journals cite from a range of linguistic traditions, as do non-English-language articles in a convenience sample of established European-language journals. We also find evidence that work in English has more influence on work in other languages than vice versa and that when non-Anglophone philosophers cite recent work outside of their own linguistic tradition it tends to be work in English. (shrink)