According to Paul Kiparsky, Lachmann's law is an example of a sound law that affects deep phonological structure, not the surface result of phonological rules. In Proto-Indo-European, a voiced stop was already pronounced as voiceless before voiceless stops, as the assimilation by
voicedness must have been operational in PIE ( → 'forced, made'). Lachmann's law, however, did not act upon the result of the assimilation, but on the deep structure > > . Jay Jasanoff defends the
Neogrammarian analysis of Lachmann's law as analogy followed by sound change. ( ⇒ * > * > ). Although this formulation ultimately derives from
Ferdinand de Saussure, Jasanoff's formulation also explains problems such as: • > * > • - ⇒ *- > • > * ⇒ * > * > Because Lachmann's law also does not operate before PIE voiced aspirate stops,
glottalic theory reinterprets the law as reflecting lengthening before glottalized stops, not voiced stops. ==See also==