After waking from his dogmatic slumber, Immanuel Kant wrote The Critique of Pure Reason in which he pronounced a requiescat over all preceding philosophy. But his attempt to begin ab ovo is done under the aegis of Ovid and Persius. In the preface he unabashedly quotes these Latin writers with the clear assumption that his 18th-century readers will know them as well as he did. Descartes wrote philosophical treatises in Latin as well as in French providing a linguistic continuity with the tradition he was determined to replace. The earliest philosophers wrote in verse and it was only gradually that philosophy became prosaic.
Modern philosophy begins in Latin and presumes a classical culture.
The history of modern philosophy could be told in terms of the gradual abandonment of Latin, both the medium and the message. In the 20th century its occurrence is as quaint as references to Greek in the 12th century and indeed, as in the earlier century's Greek, the twentieth century's Latin is likely to be a matter of titles only. In the one, Proslogion , Metalogion and the like, in the other the Tractatus Logico-Philosophicus . Titular rather than real. The true mainstream came to look counter-cultural during this retreat to Babel, the upshot of which was German Philosophy, French Philosophy, British Philosophy, and, the colonial offshoot of the above, American Philosophy.