Editing Comparative method (section)

==Complications==

===The history of historical linguistics===
The limitations of the comparative method were recognized by the very linguists who developed it,<ref>{{harvnb|Lyovin|1997|pp=4–5, 7–8}}.</ref> but it is still seen as a valuable tool. In the case of Indo-European, the method seemed at least a partial validation of the centuries-old search for an [[Ursprache]], the original language. The others were presumed to be ordered in a [[family tree]], which was the [[tree model]] of the [[neogrammarians]].

The archaeologists followed suit and attempted to find archaeological evidence of a culture or cultures that could be presumed to have spoken a [[proto-language]], such as [[Vere Gordon Childe]]'s ''The Aryans: a study of Indo-European origins'', 1926. Childe was a philologist turned archaeologist. Those views culminated in the ''Siedlungsarchaologie'', or "settlement-archaeology", of [[Gustaf Kossinna]], becoming known as "Kossinna's Law". Kossinna asserted that cultures represent ethnic groups, including their languages, but his law was rejected after World War II. The fall of Kossinna's Law removed the temporal and spatial framework previously applied to many proto-languages. Fox concludes:<ref>{{harvnb|Fox|1995|pp=141–2}}.</ref>
<blockquote>The Comparative Method ''as such'' is not, in fact, historical; it provides evidence of linguistic relationships to which we may give a historical interpretation.... [Our increased knowledge about the historical processes involved] has probably made historical linguists less prone to equate the idealizations required by the method with historical reality.... Provided we keep [the interpretation of the results and the method itself] apart, the Comparative Method can continue to be used in the reconstruction of earlier stages of languages.</blockquote>

Proto-languages can be verified in many historical instances, such as Latin.<ref>{{Cite book |last=Kortlandt |first=Frederik |url=https://www.worldcat.org/oclc/697534924 |title=Studies in Germanic, Indo-European and Indo-Uralic |date=2010 |publisher=Rodopi |isbn=978-90-420-3136-4 |location=Amsterdam |oclc=697534924}}</ref><ref>{{Cite book |last=Koerner |first=E. F. K. |url=https://www.worldcat.org/oclc/742367480 |title=Linguistic historiography : projects & prospects |date=1999 |publisher=J. Benjamins |isbn=978-90-272-8377-1 |location=Amsterdam |oclc=742367480}}</ref> Although no longer a law, settlement-archaeology is known to be essentially valid for some cultures that straddle history and prehistory, such as the Celtic Iron Age (mainly Celtic) and [[Mycenaean civilization]] (mainly Greek). None of those models can be or have been completely rejected, but none is sufficient alone.

===The Neogrammarian principle===
The foundation of the comparative method, and of comparative linguistics in general, is the [[Neogrammarian]]s' fundamental assumption that "sound laws have no exceptions". When it was initially proposed, critics of the Neogrammarians proposed an alternate position that summarised by the maxim "each word has its own history".<ref>{{harvnb|Szemerényi|1996|p=23}}.</ref> Several types of change actually alter words in irregular ways. Unless identified, they may hide or distort laws and cause false perceptions of relationship.

====Borrowing====
All languages [[loanword|borrow words]] from other languages in various contexts. Loanwords imitate the form of the donor language, as in Finnic ''kuningas'', from Proto-Germanic *''kuningaz'' ('king'), with possible adaptations to the local phonology, as in Japanese ''sakkā'', from English ''soccer''. At first sight, borrowed words may mislead the investigator into seeing a genetic relationship, although they can more easily be identified with information on the historical stages of both the donor and receiver languages. Inherently, words that were borrowed from a common source (such as English ''coffee'' and Basque ''kafe'', ultimately from Arabic ''qahwah'') do share a genetic relationship, although limited to the history of this word.

====Areal diffusion====
Borrowing on a larger scale occurs in [[areal feature (linguistics)|areal diffusion]], when features are adopted by contiguous languages over a geographical area. The borrowing may be [[Phonology|phonological]], [[Morpheme|morphological]] or [[Lexeme|lexical]]. A false proto-language over the area may be reconstructed for them or may be taken to be a third language serving as a source of diffused features.<ref>{{harvnb|Aikhenvald|2001|pp=2–3}}.</ref>

Several areal features and other influences may converge to form a [[Sprachbund]], a wider region sharing features that appear to be related but are diffusional. For instance, the [[Mainland Southeast Asia linguistic area]], before it was recognised, suggested several false classifications of such languages as [[Chinese language|Chinese]], [[Thai language|Thai]] and [[Vietnamese language|Vietnamese]].

====Random mutations====
Sporadic changes, such as irregular inflections, compounding and abbreviation, do not follow any laws. For example, the [[Spanish language|Spanish]] words ''palabra'' ('word'), ''peligro'' ('danger') and ''milagro'' ('miracle') would have been ''parabla'', ''periglo'', ''miraglo'' by regular sound changes from the Latin ''parabŏla'', ''perīcŭlum'' and ''mīrācŭlum'', but the ''r'' and ''l'' changed places by sporadic [[metathesis (linguistics)|metathesis]].<ref>{{harvnb|Campbell|2004|p=39}}.</ref>

====Analogy====
[[Analogy#Linguistics|Analogy]] is the sporadic change of a feature to be like another feature in the same or a different language. It may affect a single word or be generalized to an entire class of features, such as a verb paradigm. An example is the [[Russian language|Russian]] word for ''nine''. The word, by regular sound changes from [[Proto-Slavic]], should have been {{IPA|/nʲevʲatʲ/}}, but it is in fact {{IPA|/dʲevʲatʲ/}}. It is believed that the initial ''{{IPA|nʲ-}}'' changed to ''{{IPA|dʲ-}}'' under influence of the word for "ten" in Russian, {{IPA|/dʲesʲatʲ/}}.<ref>{{harvnb|Beekes|1995|p=79}}.</ref>

====Gradual application====
Those who study contemporary language changes, such as [[William Labov]], acknowledge that even a systematic sound change is applied at first inconsistently, with the percentage of its occurrence in a person's speech dependent on various social factors.<ref>{{harvnb|Beekes|1995|p=55}}; {{harvnb|Szemerényi|1996|p=3}}.</ref> The sound change seems to gradually spread in a process known as [[lexical diffusion]]. While it does not invalidate the Neogrammarians' axiom that "sound laws have no exceptions", the gradual application of the very sound laws shows that they do not always apply to all lexical items at the same time. Hock notes,<ref>{{harvnb|Hock|1991|pp=446–447}}.</ref> "While it probably is true in the long run every word has its own history, it is not justified to conclude as some linguists have, that therefore the Neogrammarian position on the nature of linguistic change is falsified".

====Non-inherited features====
The comparative method cannot recover aspects of a language that were not inherited in its daughter idioms. For instance, the [[Latin declension]] pattern was lost in [[Romance languages]], resulting in an impossibility to fully reconstruct such a feature via systematic comparison.{{Sfn|Meillet|1966|p=13}}

===The tree model===
The comparative method is used to construct a tree model (German ''Stammbaum'') of language evolution,<ref>{{harvnb|Lyovin|1997|pp=7–8}}.</ref> in which daughter languages are seen as branching from the [[proto-language]], gradually growing more distant from it through accumulated [[phonology|phonological]], [[morpho-syntactic]], and [[lexicon|lexical]] changes.
[[File:Uto-Aztecan Family Tree.jpg|thumb|720px|center|An example of the Tree Model, used to represent the [[Uto-Aztecan languages|Uto-Aztecan]] language family spoken throughout the southern and western United States and Mexico.<ref>The diagram is based on the hierarchical list in {{harvnb|Mithun|1999|pp=539–540}} and on the map in {{harvnb|Campbell|1997|p=358}}.</ref> Families are in '''bold''', individual languages in ''italics''. Not all branches and languages are shown.]]

====The presumption of a well-defined node====
[[File:Wave model Schmidt.svg|thumb|upright=1.3|The [[Wave model (linguistics)|Wave Model]] has been proposed as an alternative to the [[tree model]] for representing language change.<ref>This diagram is based partly on the one found in Fox 1995:128, and Johannes Schmidt, 1872. ''Die Verwandtschaftsverhältnisse der indogermanischen Sprachen''. Weimar: H. Böhlau</ref> In this [[Venn diagram]], each circle represents a "wave" or [[isogloss]], the maximum geographical extension of a linguistic change as it propagated through the speaker population. These circles, which represent successive historical events of propagation, typically intersect. Each language in the family differs as to which isoglosses it belongs to: which innovations it reflects. The tree model presumes that all the circles should be nested and never crosscut, but studies in [[dialectology]] and historical linguistics show that assumption to be usually wrong and suggest that the wave-based approach may be more realistic than the tree model. A genealogical family in which isoglosses intersect is called a [[dialect continuum]] or a ''[[linkage (linguistics)|linkage]]''.]]

The tree model features nodes that are presumed to be distinct proto-languages existing independently in distinct regions during distinct historical times. The reconstruction of unattested proto-languages lends itself to that illusion since they cannot be verified, and the linguist is free to select whatever definite times and places seems best. Right from the outset of Indo-European studies, however, [[Thomas Young (scientist)|Thomas Young]] said:<ref>{{citation|title=Miscellaneous works of the late Thomas Young|first=Thomas|last=Young|contribution=Languages, From the Supplement to the Encyclopædia Britannica, vol. V, 1824|volume=III, Hieroglyphical Essays and Correspondence, &c.|editor-first=John|editor-last=Leitch|location=London|publisher=John Murray|year=1855|page=480}}</ref><blockquote>It is not, however, very easy to say what the definition should be that should constitute a separate language, but it seems most natural to call those languages distinct, of which the one cannot be understood by common persons in the habit of speaking the other.... Still, however, it may remain doubtfull whether the Danes and the Swedes could not, in general, understand each other tolerably well... nor is it possible to say if the twenty ways of pronouncing the sounds, belonging to the Chinese characters, ought or ought not to be considered as so many languages or dialects.... But,... the languages so nearly allied must stand next to each other in a systematic order…</blockquote>

The assumption of uniformity in a proto-language, implicit in the comparative method, is problematic. Even small language communities always have differences in [[dialect]], whether they are based on area, gender, class or other factors. The [[Pirahã language]] of [[Brazil]] is spoken by only several hundred people but has at least two different dialects, one spoken by men and one by women.<ref>{{harvnb|Aikhenvald|1999|p=354}}; {{harvnb|Ladefoged|2003|p=14}}.</ref> Campbell points out:<ref>{{harvnb|Campbell|2004|pp=146–147}}</ref>
<blockquote>It is not so much that the comparative method 'assumes' no variation; rather, it is just that there is nothing built into the comparative method which would allow it to address variation directly.... This assumption of uniformity is a reasonable idealization; it does no more damage to the understanding of the language than, say, modern reference grammars do which concentrate on a language's general structure, typically leaving out consideration of regional or social variation.</blockquote>

Different dialects, as they evolve into separate languages, remain in contact with and influence one another. Even after they are considered distinct, languages near one another continue to influence one another and often share grammatical, phonological, and [[lexical innovation]]s. A change in one language of a family may spread to neighboring languages, and multiple waves of change are communicated like waves across language and dialect boundaries, each with its own randomly delimited range.<ref>{{harvnb|Fox|1995|p=129}}</ref> If a language is divided into an inventory of features, each with its own time and range ([[isogloss]]es), they do not all coincide. History and prehistory may not offer a time and place for a distinct coincidence, as may be the case for [[Proto-Italic language|Proto-Italic]], for which the proto-language is only a concept. However, Hock<ref>{{harvnb|Hock|1991|p=454}}.</ref> observes:

<blockquote>The discovery in the late nineteenth century that [[isogloss]]es can cut across well-established linguistic boundaries at first created considerable attention and controversy. And it became fashionable to oppose a wave theory to a tree theory.... Today, however, it is quite evident that the phenomena referred to by these two terms are complementary aspects of linguistic change....</blockquote>

====Subjectivity of the reconstruction====
The reconstruction of unknown proto-languages is inherently subjective. In the [[Proto-Algonquian]] example above, the choice of ''*m'' as the parent [[phoneme]] is only ''likely'', not ''certain''. It is conceivable that a Proto-Algonquian language with ''*b'' in those positions split into two branches, one that preserved ''*b'' and one that changed it to ''*m'' instead, and while the first branch developed only into [[Arapaho language|Arapaho]], the second spread out more widely and developed into all the other [[Algonquian peoples|Algonquian]] tribes. It is also possible that the nearest common ancestor of the [[Algonquian languages]] used some other sound instead, such as ''*p'', which eventually mutated to ''*b'' in one branch and to ''*m'' in the other.

Examples of strikingly complicated and even circular developments are indeed known to have occurred (such as Proto-Indo-European ''*t'' > Pre-Proto-Germanic ''*þ'' > [[Proto-Germanic]] ''*ð'' > Proto-West-Germanic ''*d'' > [[Old High German]] {{lang|goh|t}} in {{lang|goh|fater}} > Modern German {{lang|de|Vater}}), but in the absence of any evidence or other reason to postulate a more complicated development, the preference of a simpler explanation is justified by the principle of parsimony, also known as [[Occam's razor]]. Since reconstruction involves many such choices, some linguists{{who|date=January 2020}} prefer to view the reconstructed features as abstract representations of sound correspondences, rather than as objects with a historical time and place.{{citation needed|date=January 2020}}

The existence of proto-languages and the validity of the comparative method is verifiable if the reconstruction can be matched to a known language, which may be known only as a shadow in the [[loanword]]s of another language. For example, [[Finnic languages]] such as [[Finnish language|Finnish]] have borrowed many words from an early stage of [[Germanic languages|Germanic]], and the shape of the loans matches the forms that have been reconstructed for [[Proto-Germanic]]. Finnish {{lang|fi|kuningas}} 'king' and {{lang|fi|kaunis}} 'beautiful' match the Germanic reconstructions *''kuningaz'' and *''skauniz'' (> German {{lang|de|König}} 'king', {{lang|de|schön}} 'beautiful').<ref>{{harvnb|Kylstra|1996|p=62}} for KAUNIS, p. 122 for KUNINGAS.</ref>

====Additional models====
The [[wave model]] was developed in the 1870s as an alternative to the tree model to represent the historical patterns of language diversification. Both the tree-based and the wave-based representations are compatible with the comparative method.<ref>[[#linkage|François 2014]], [[#kf|Kalyan & François 2018]].</ref>

By contrast, some approaches are incompatible with the comparative method, including contentious [[glottochronology]] and even more controversial [[mass lexical comparison]] considered by most historical linguists to be flawed and unreliable.<ref>{{harvnb|Campbell|2004|p=201}}; {{harvnb|Lyovin|1997|p=8}}.</ref>