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The comparative method (in linguistics) is a method used to detecting genetic relationships between languages and to establish a consistent relationship hypothesis by reconstructing:- the common ancestor of the languages in question,
- a plausible sequence of regular changes by which the historically known languages can be derived from that common ancestor.
The comparative method is the "gold standard" by which mainstream linguists judge whether two languages are related; relation is deemed certain only if a reconstruction of the common ancestor (or at least a partial reconstruction) is feasible. Other approaches to the problem that have been proposed, such as Joseph H. Greenberg's " mass lexical comparison" method, are still considered too unreliable by most linguists.
1 Related languages
In the present context, "related" has a specific meaning: two languages are said to be related if they are descended from the same ancestor language. Thus, for example, Spanish and French are both descended from Latin. "Descent", in turn, is defined in terms of transmission across the generations: children learn a language from the parents' generation, transmit it in slightly changed form to the next generation, and so on. A continuous chain of speakers across the centuries links Classical Latin to all of its modern descendants.
This definition of relatedness implies that even if two languages are quite similar in their vocabularies, they are not necessarily closely related. Modern Persian in fact takes more of its words from Arabic than from its direct ancestor, Proto-Indo-Iranian. This is because of heavy borrowing over the years from Arabic into Persian. But under the definition just given, Persian is considered to be descended from Proto-Indo-Iranian, and not from Arabic.
The comparative method is a method for proving relatedness in the sense just given.
2 How the comparative method works
The essential steps are as follows:
- Relationship between two (or more) languages can be suspected if they show a number of regular correspondences in lexicon, which means that there is a regularly recurring match between the phonetic structure of words with similar meanings (one usually begins with characteristic sets like family terms, numerals, body parts, etc.). The notion of regular correspondence is very important here: mere phonetic similarity, as between English day and Latin dies (same meaning), has no probative value. English initial [d-] does not regularly match Latin [d-], and whatever sporadic matches can be observed are due either to chance (as in the above example) or to borrowing (e.g. Latin diabolus, English devil, both ultimately of Greek origin).
- There is, however, a regular correspondence between Latin [d-] and English [t-]:
- decem | ten
- duo | two
- duco | tow
- Old Latin dingua | tongue
- Closer analysis reveals that the correspondence is both regular and pervasive, and that it is part of a more general regular pattern ( Grimm's law)
- More trivial equations also hold between Latin and English:
- mater | mother
- ment- | mind
- mus | mouse
- They demonstrate that Latin word-initial [m] corresponds to English [m]. However, it is the regularity of the matches, not the identity of sound, that counts here.
- A really systematic correspondence can hardly be accidental. If we can rule out alternative possibilities like massive borrowing, the correspondence can be attributed to common descent. If there are many regular correspondence sets of this kind (the more the better), and if they add up to a sensible pattern (one that could have been produced by known types of sound change), common origin becomes a virtual certainty.
- On the basis of regular correspondence sets formulate a relationship hypothesis, involving an attempt to reconstruct the hypothetical ancestor of the languages being compared. Without going into detail, Latin [d] and English [t] are both derived from primitive *d (the asterisk means that the sound is inferred rather than historically documented) in the reconstructible common ancestor of both languages (called Proto-Indo-European or PIE for short). We also attempt to recover the past sound changes responsible for the historically known reflexes of the reconstructed protoform. For example (the symbol > should be read as "became"):
- PIE *dek^m > Proto-Germanic *texun > Old English teon (attested, yielding Modern English ten)
- PIE *dek^m > Proto-Italic *dekem > Latin decem (c = /k / in Classical Latin)
- PIE *dek^m > Proto-Indo-Iranian *daCa > Sanskrit das′a
- PIE *dek^m > Greek deka
- Each step must be justified, e.g. *k^ > *x (the sound of German ch) is part of a regular pattern seen also in Latin cord- | Germanic *xert- 'heart' (> English heart, German Herz) and many similar equations. The weakening and loss of this *x between vowels in the history of English (*-x- > *-h- > zero) is also regular. So are other changes visible in these word histories, e.g. the development of the syllabic nasal at the end of the word into Greek and Indo-Iranian [a], the change *e > *a (or rather the falling together of *e, *o and *a) in Indo-Iranian, or the so-called Satem development of *k^ in the same group (giving a Sanskrit palatal fricative via an Indo-Iranian palatal affricate).
- Regular sound changes form historical sequences and often "feed" one another (an older change creates an environment in which more recent changes apply).
- The reconstruction of proto-sounds and their historical transformations enables us to proceed further: we can compare grammatical morphemes (word-forming affixes and inflectional endings), patterns of declension and conjugation, and so on. The full reconstruction of an unrecorded protolanguage can never be complete (for example, proto- syntaxThe first meaning of the term syntax originating from the Greek words (sun, meaning ‘together’) and (taxis, meaning sequence/order), can be described as the study of the rules, or "patterned relations" that govern the way the words in a sentence come toge is far more elusive than phonologyPhonology is a subfield of grammar (see also linguistics). Whereas phonetics is about the nature of sounds (or phones) per se, phonology describes the way sounds function within a given language. For example, /p/ and /b/ in English are distinctive units o or morphologyMorphology is the following: In linguistics, morphology is the study of the structure of word forms. In biology, morphology is the study of the form or shape of an organism or part thereof. It can also be used to describe the form or shape of patterns for, and all elements of linguistic structure undergo inevitable erosion and gradual loss or replacement over time), but a consistent partial reconstruction can and must be attempted as proof of genetic relationship.
