A methodological principle in historical phonology proposing that sound change operates according to systematic phonetic laws that apply uniformly to all lexical items in the same phonetic environment; apparent exceptions are attributed to independent secondary processes such as analogy, borrowing, or morphological conditioning.

Principle

Treat regular, context‑conditioned phonetic change as the default explanation for systematic correspondences; explain deviations by secondary mechanisms rather than by abandoning regularity without evidence.

Demonstration

Illustrative scenario → In a reconstructed stage, a phonetic shift (e.g., voiceless stop → fricative) affects all tokens of that stop in intervocalic position across the lexicon. Recognition → Cognate sets across dialects consistently reflect the shift. Action → Infer a systematic sound law and use it in comparative reconstruction. Consequence → Regular correspondence patterns support reconstruction of ancestral forms.

Misapplication

Inferring a regular sound law from a small, biased sample or ignoring evidence of analogy, lexical borrowing, morphosyntactic conditioning, or gradual lexical diffusion that better explain exceptions.

Consequence

Provides the methodological basis for the comparative method and for systematic reconstruction of earlier phonological stages; it focuses analysis on patterned correspondences rather than on isolated alternations.

Reversal

Circumstances such as lexical diffusion (gradual, word‑by‑word spread), strong morphological conditioning, rapid contact and borrowing, or sociolinguistic variation can produce genuine and systematic deviations from strict uniform application.

Boundary

Pertains to historical phonological change and comparative reconstruction; does not directly govern synchronic phonological alternations, performance phenomena, or non-phonetic causes of variation.

Semantic Tension

Tension between explanatory regularity (seeking systemwide phonetic laws) and evidence for incremental, lexically heterogeneous, or socially mediated change.

Synthesis

The Neogrammarian hypothesis is a powerful methodological default: assume regularity to identify sound laws, but remain alert to documented secondary processes that legitimately produce exceptions.