One of the most original, if not one of the most immediately influential, linguists of the 19th century was the learned Prussian statesman Wilhelm von Humboldt (died 1835). His interests, unlike those of most of his contemporaries, were not exclusively historical.

One of the central figures involved in this development was the German philosopher Gottlob Frege, whose work on philosophical logic and the philosophy of language in the late 19th century influenced the work of 20th-century analytic philosophers Bertrand Russell and Ludwig Wittgenstein.

Philosophy of linguistics is the philosophy of science as applied to linguistics. This differentiates it sharply from the philosophy of language, traditionally concerned with matters of meaning and reference.

John Stuart Mill (1806–73) was the most influential English language philosopher of the nineteenth century. He was a naturalist, a utilitarian, and a liberal, whose work explores the consequences of a thoroughgoing empiricist outlook.

Modern philosophy - The 19th century: Kant’s death in 1804 formally marked the end of the Enlightenment. The 19th century ushered in new philosophical problems and new conceptions of what philosophy ought to do. It was a century of great philosophical diversity.