After World War One more scientific techniques were applied to the study of language, induced by discoveries in theoretical research and archaeology. One of the most prominent scholars of this period is N.S. Trubetzkoy who, in his book titled in English Principles of Phonology (1939) “made signal contribution of combining Saussure’s social view of the system of language with the psychological view of the neogrammarians” (Lehmann 37). One of the important topics in the Principles was the notion of marking. Trubetzkoy used the oppositions of sounds to prove their distinction, as linguists did in 1920s, but he used the term “marked element” to label “the entity with the feature that is lost …” (Lehmann 38). The concept of “markedness” is today regarded as “linguistically central” (Trask 163), especially because it was successfully extended to grammar and lexicology (Lehmann 38). Roman Jakobson, who greatly contributed to generative linguistics, later introduced the use of distinctive features, instead of the whole phonemes, thus extending the concept of marking. As Lehman states, rules derived from distinctive feature were much more precise that those from the entire phonemes, which further systematically strengthened the findings of historical linguistics.
Noam Chomsky is one on the greatest linguists and thinkers of the twentieth century. He is credited for significant shift towards synchronic examination of language within historical linguistics. However, the influence was mutual, since the discipline itself affected Chomsky’s philosophy. Reading historical linguistics motivated Chomsky to develop a “rationalist” approach. This was in contrast with the then current “empirists’ view” that human mind gets all content by “’learning’ it from environmental conditions” (McGilvray 14):
The rationalist recognizes, of course, that experience and “external” factors play a role in the mind’s “choosing” which concepts to activate or develop. But the rationalist denies that external elements shape and constitute concepts via the operations of some sort of domain-general learning procedure such as hypothesis formation and testing. Circumstances serve to “occasion” or “trigger” the introduction of a concept; crucially, the mind’s own machinery dictates what “patterns” in the data count as appropriate “occasions.” The patterns are, in a sense, built into the mind all along. (ibid)
This would give rise to new theories with a focus on language acquisition, again reaffirming the significance of contemporary language examination for historical linguistics.