What is most central to Humboldt’s argument about the diversity of languages is not the relativity of thought to language and therefore the contingent plurality of linguistic and intellectual perspectives, but the universal human need for diversity and therefore for communication which that plurality implies.

In his “Introduction to the Whole Study of Language,” Humboldt writes as follows: “Vermutlich ist der eigentliche Grund der Vielheit der Sprachen das innere Bedürfnis des menschlichen Geistes, eine Mannigfaltigkeit intellectueller Formen hervorzubringen, welche Schranke auf uns gleich unbekannte Weise, als die Mannigfaltigkeit der belebten Naturbildungen, findet” (GS, 7, 2:622; The real reason for the multiplicity of languages is probably the inner need of the human mind to bring forth a multiplicity of intellectual forms. The limit to that diversity is as incomprehensible to us as the limit to the formation of organisms in the natural world). Humboldt’s analogy between languages and the living forms of the natural world does not therefore mean that he considers the development or interaction of languages to be an “organic” process in any teleological sense, especially not as a sign of historical or cultural progress. For Humboldt, neither the diversity of languages nor the ways in which they change can be conceived as having any “purpose” external to the living reality of language itself. There is no a priori reason why a particular finite number of languages exist, nor why they should develop in a particular way. The world of language is what Karl Popper, in his account of the Darwinian paradigm of evolution, calls “a world of propensities,” where living organisms may have “propensities” to develop in certain ways but in which we can never predict the outcome of their contingent interaction. Although Humboldt’s linguistic writings predate Darwin’s Theory of Evolution (1859) by at least thirty years, his understanding of the “organic” development of language has more in common with Darwin than Kant. For Humboldt, languages do not develop toward or because of a teleological end (“diese Ansicht ist gänzlich von der der Zwecke verschieden”) but as living organisms interacting with each other: