According to the Neogrammarian hypothesis, a diachronicsound change affects simultaneously all words in which its environment is met, without exception. Verner's law is a famous example of the Neogrammarian hypothesis, as it resolved an apparent exception to Grimm's law. The Neogrammarian hypothesis was the first hypothesis of sound change to attempt to follow the principle of falsifiability according to scientific method. Subsequent researchers have questioned this hypothesis from two perspectives. First, adherents of lexical diffusionbelieve that some words undergo changes before others. Second, some believe that it is possible for sound changes to observegrammatical conditioning. Nonetheless, both of these challenges to exceptionlessness remain controversial, and many investigators continue to adhere to the Neogrammarian doctrine. Other contributions of the Neogrammarians to general linguistics were:
The object of linguistic investigation is not the language system, but rather the idiolect, that is, language as it is localized in the individual, and therefore is directly observable.
Autonomy of the sound level: being the most observable aspect of language, the sound level is seen as the most important level of description, and absolute autonomy of the sound level from syntax and semantics is assumed.
Historicism: the chief goal of linguistic investigation is the description of the historical change of a language.
Analogy: if the premise of the inviolability of sound laws fails, analogy can be applied as an explanation if plausible. Thus, exceptions are understood to be a adaptation to a related form.
Leading Neogrammarian linguists included:
Otto Behaghel
Wilhelm Braune
Karl Brugmann
Berthold Delbrück
August Leskien
Adolf Noreen
Hermann Osthoff
Hermann Paul
Eduard Sievers
Despite their strong influence in their time, the methods and goals of the Neogrammarians have been criticized for reducing the object of investigation to the idiolect; restricting themselves to the description of surface phenomena ; overvaluation of historical languages and neglect of contemporary ones.
