Varieties of Modern Greek
The linguistic varieties of Modern Greek can be classified along two principal dimensions. First, there is a long tradition of sociolectal variation between the natural, popular spoken language on the one hand and archaizing, learned written forms on the other. Second, there is regional variation between dialects. The competition between the popular and the learned registers culminated in the struggle between Dimotiki and Katharevousa during the 19th and 20th centuries. As for regional dialects, variation within the bulk of dialects of present-day Greece is not particularly strong, except for a number of outlying, highly divergent dialects spoken by isolated communities.
Diglossia
Roots and history: Demotic and Katharevousa
Ever since the times of Koiné Greek in Hellenistic and Roman antiquity, there was a competition between the naturally evolving spoken forms of Greek on the one hand, and the use of artificially archaic, learned registers on the other. The learned registers employed grammatical and lexical forms in imitation of classical Attic Greek. This situation is known in modern linguistics as diglossia.During the Middle Ages, Greek writing varied along a continuum between extreme forms of the high register very close to Attic, and moderate forms much closer to the spoken Demotic. According to Manolis Triantafyllides, the modern Greek language of the beginning of the 19th century, as used in the demotic poetry of the time, has very few grammatical differences from the vernacular language of the 15th century. During the early Modern Era, a middle-ground variety of moderately archaic written standard Greek emerged in the usage of educated Greeks and the Greek church; its syntax was essentially Modern Greek. After the Greek War of Independence and the formation of the modern Greek state, a political effort was made to "purify" this form of Greek by bringing it back to resemble classical Attic Greek more closely. The result was Katharevousa, still a compromise form with basically Modern Greek syntax, but re-lexified with a much larger amount of Ancient Greek words and morphology. Katharevousa was used as an official language in administration, education, the church, journalism, and in literature.
At the same time, spoken Demotic, while not recognised as an official language, nevertheless developed a supra-regional, de facto standard variety. From the late 19th century onwards, written Demotic rather than Katharevousa became the primary medium of literature. During much of the 20th century, there were heated political conflicts over the use of either of the two varieties, especially over the issue of their use in education. Schools were forced to switch from one form to the other and back several times during the 20th century. The conflict was resolved only after the overthrow of the Greek military junta of 1967–1974, whose strong ideological pro-Katharevousa stance had ultimately contributed to bringing that language form into disrepute. In 1976, shortly after the restoration of democracy, Demotic was finally adopted for use everywhere in education and became the language of the state for all official purposes. By that time, however, the form of Demotic used in practice was no longer the pure popular dialect, but had begun to assimilate elements from the Katharevousa tradition again. In 1982 diacritics were replaced by the monotonic orthography.
Standard Modern Greek
Modern linguistics has come to call the resulting variety "Standard Modern Greek" to distinguish it from the pure original Demotic of earlier literature and traditional vernacular speech. Greek authors sometimes use the term "Modern Greek Koiné", reviving the term koiné that otherwise refers to the "common" form of post-classical Ancient Greek; according to these scholars, Modern Greek Koiné is the "supra-dialect product of the composition of both the Demotic and Katharevousa." Indeed, Standard Modern Greek has incorporated a large amount of vocabulary from the learned tradition, especially through the registers of academic discourse, politics, technology and religion; together with these, it has incorporated a number of morphological features associated with their inflectional paradigms, as well as some phonological features not originally found in pure Demotic.History of modern Greek dialects
The first systematic scholarly treatment of the modern Greek dialects took place after the middle of the 19th century, mainly thanks to the work of the prominent Greek linguist Georgios Hadjidakis. The absence of descriptive accounts of the speech of individual regions made the efforts of the researchers of the 19th century more difficult. Therefore, the dialects' forms are known to us only during their last phase.Initial dialect differentiation
Modern linguistics is not in accord with the tendency of the 19th century scholars to regard modern Greek dialects as the direct descendants of the dialects of ancient Greek. According to the latest findings of scholarship, modern Greek dialects are products of the dialect differentiation of Koiné Greek, and, with the exception of Tsakonian and possibly Italiot Greek, they have little correlation with the ancient dialects.It is difficult to monitor the evolution of Koiné Greek and its splitting into the modern Greek dialects; certain researchers make the hypothesis that the various local varieties were formed between the 10th and the 12th century, but it is difficult to draw some safer conclusions because of the absence of texts written in the vernacular language, when this initial dialect differentiation occurred. Very few paradigms of these local varieties are found in certain texts, which used mainly learned registers. The first texts written in modern Greek dialects appear during the Early Renaissance on the islands of Cyprus and Crete.
Historical literary dialects
Before the establishment of a common written standard of Demotic Greek, there were various approaches to using regional variants of Demotic as a written language. Dialect is recorded in areas outside Byzantine control, first in legal and administrative documents, and then in poetry. The earliest evidence for literary dialects comes from areas under Latin control, notably from Cyprus, Crete, and the Aegean islands. From Cyprus under the Lusignan dynasty, legal documents, prose chronicles, and a group of anonymous love poems have survived. Dialect archives also survive from 15th century Naxos.It is above all from the island of Crete, during the period of Venetian rule from 1204 until its capture by the Ottomans in 1669, that dialect can be illustrated more fully. Documents showing dialectal features exist from the end of the 12th century, rapidly increasing in number from the 13th century onward. During the Cretan Renaissance in the 16th and early 17th centuries there existed a flourishing vernacular literature in the Cretan dialect, based on Italian literary influences. Its best-known specimen today is the verse romance Erotokritos, by Vitsentzos Kornaros.
Later, during the 18th and early 19th centuries, the Ionian Islands, then also under Italian rule, became a centre of literary production in Demotic Greek. The best-known writer from that period was the poet Dionysios Solomos, who wrote the Greek national anthem and other works celebrating the Greek Revolution of 1821–1830. His language became influential on the further course of standardisation that led to the emergence of the modern standard form of Demotic, based on the south-western dialects.