Grimm’s Law

Grimm’s Law, described by Jacob Grimm in his "Deutsche Grammatik" (1819–37; “Germanic Grammar”), outlines regular correspondences in Indo-European languages. It highlighted significant correlations between the Germanic languages and other Indo-European languages of Europe and western Asia. The law, systematically and coherently formulated with numerous examples, built on patterns recognized as early as 1814 by Danish philologist Rasmus Kristian Rask. Grimm’s Law is crucial for historical linguistics because it demonstrates that sound change is a regular phenomenon, not a random process affecting only some words, as previously thought.

Grimm described two consonant shifts involving nine consonants. The first shift, occurring likely a few centuries before the Christian era, affected Indo-European consonants and is evident in English, Dutch, other Low German languages, and Old Norse. The second shift, around the 6th century CE, was less radical and affected Germanic consonants, resulting in the consonant system of Old High German and its descendants, Middle High German and Modern High German (standard German). According to Grimm’s Law:

The ancient unvoiced consonants p, t, k became the English unvoiced consonants f, th, h and the Old High German consonants f, d, h, resulting in correlations such as Greek pod-, English foot, and Old High German fuo.

The ancient voiced consonants b, d, g became the English unvoiced consonants p, t, k and the Old High German spirant stops f, ts, kh, illustrated by the correlation between Latin duo, English “two,” and modern German zwei (pronounced “tsvai”).

The originally voiced aspirated consonants bh, dh, gh became the English voiced consonants b, d, g and the Old High German consonants p, t, k. For example, compare Sanskrit bhárati, English “bear,” and the Upper German dialects of Old High German ki-peran (later standard German ge-bären). The Old High German examples exhibit both the first and second shifts, whereas English only shows the first shift.

Grimm's Law identifies sound changes that distinguish Germanic languages from their Proto-Indo-European origins. These changes occurred in prehistory but have left traces in modern languages.

A sound shift involves two main components:

1. A phoneme changes to another phoneme in specific contexts.

2. Every word containing the original phoneme adopts the new pronunciation.

The discovery of these sound changes marked the beginning of comparative historical linguistics. Sir William Jones, after returning from his judicial role in British-controlled India, delivered a lecture at the Royal Asiatick Society around 1800. He proposed that Sanskrit, Latin, Greek, and German were related languages and provided evidence for this claim. This led to the discovery of sound shifts now known as Grimm's Law, first identified by Rasmus Rask and shortly after by Jacob Grimm (of the Brothers Grimm). Grimm's greater fame resulted in the law being named after him.

Comparative historical linguistics is straightforward, beginning with observed similarities (datasets of related words) and a hypothesis that these similarities arise from common descent. Sound shifts are then postulated to explain the relationships between the forms in the datasets.

The neogrammarian hypothesis asserts that a sound shift affects every instance of that sound in a language. These shifts can be narrowly defined (e.g., changes occurring only between vowels) or broadly applied. The key is specifying the environment in which the shift occurs.

In Modern English, we can find examples of descendants from the same Proto-Indo-European root word in various forms. Some of these forms underwent the shifts identified by Grimm's Law in Proto-Germanic, while others did not, leading to the diversity we observe today.

Grimm's Law consists of three parts, forming consecutive phases in a chain shift. These phases are typically described as follows:

Proto-Indo-European voiceless stops change into voiceless fricatives.

Proto-Indo-European voiced stops become voiceless stops.

Proto-Indo-European voiced aspirated stops become voiced stops or fricatives (as allophones).

This chain shift can be abstractly represented as:

bʰ → b → p → f

dʰ → d → t → θ

gʰ → g → k → x

gʷʰ → gʷ → kʷ → xʷ

In this representation, each sound shifts one position to the right to take on its new sound value. Within Proto-Germanic, the sounds denoted by ⟨b⟩, ⟨d⟩, ⟨g⟩, and ⟨gw⟩ were stops in some environments and fricatives in others, so bʰ → b indicates bʰ → b/β, and similarly for the others. The voiceless fricatives are usually spelled ⟨f⟩, ⟨þ⟩, ⟨h⟩, and ⟨hw⟩ in the context of Germanic languages.

The precise details of the shift are unknown, and it may have progressed in various ways before reaching its final state. The three stages above illustrate a "pull chain," where each change creates a "gap" in the phonological system that "pulls" other phonemes into it. Alternatively, the shift could have occurred as a "push chain," with each change "pushing" the next forward to avoid phoneme mergers.

Another possible sequence of events is:

Voiceless stops are allophonically aspirated under most conditions.

Voiced stops become unaspirated voiceless stops.

All aspirated stops become fricatives.

This sequence would lead to the same result. This variant of Grimm's Law is often suggested in the context of the Proto-Indo-European glottalic theory, followed by a minority of linguists. This theory assumes that Proto-Indo-European "voiced stops" were originally voiceless, so the second phase involved losing another articulatory feature like glottalization or ejectiveness rather than devoicing. This alternative sequence also accounts for Verner's Law phonetics, which are easier to explain within the glottalic theory framework when Grimm's Law is formulated this way. Additionally, aspirated stops changing to fricatives is a known transition between Proto-Indo-European and Proto-Italic, providing a plausible parallel for the shift to Proto-Germanic.