What is the "principle of uniformity" in historical linguistics?

Question

I feel hopeless asking this. The word in question as I understand it describes that a theory has to account for all observables under discussion without exception.

In historical linguistics it is based on regular sound-laws and to a lesser degree on common sense. There's no special name for that but the Neogrammarian school of thought has been attached as a symbol. Some have used the more generic term which is in question without explicitly referencing Neogrammarians.

The last time I checked, long after I read it once in a paper, I have found only Geology related usage and shrugged it off. Some time later it occured again in a more familiar context on Wiktionary, so I have reason to believe that it actually has currency. Now, however, I remember it as "Unitarian" which brings up denominations of churches, pretty much exclusively, so I'm afraid I misremember. It very likely starts with un(i) is all I can say.

In reality I am looking for a critique of this principle as applied in practice.

Answer 1

The uniformitarian principle a.k.a. Uniformitarianism is actually a general scientific premise, that natural laws are the same at all times and places, and conservation of charge is not a quirk of the planet Earth. It obviously does not apply to man-made artifacts so is inapplicable to literature and art styles. It does not mean that the average temperature is the same everywhere at all times, but the physical laws that relate to temperature are time-and-place invariant.

Since the Neogrammarians believed that language change was the result of "natural laws", whatever was the nature of those would be the same everywhere and at all times. That does not actually mean that all languages always have Grimm's Law, so the version of Uniformatarianism that exists in Neogrammarianism is somewhat different from physics, in that it a sound change has to somehow "get started" from random phonetic variation (this part is unpredictable). Once you have a sound law in a language, it applies to everything (counterexamples are either borrowings or analogy).