Ferguson's original formulation.

Ferguson originally summarized diglossia (1959: 435) as follows:

DIGLOSSIA is a relatively stable language situation in which, in addition to the primary dialects of the language (which may include a standard or regional standards), there is a very divergent, highly codified (often grammatically more complex) superposed variety, the vehicle of a large and respected body of written literature, either of an earlier period or in another speech community, which is learned largely by formal education and is used for most written and formal spoken purposes but is not used by any section of the community for ordinary conversation.

The notion that diglossia could also be used to characterize other multilingual situations where the H and L varieties were not genetically related, such as Sanskrit (as H) and Kannada (as L) in India, was developed by Fishman (1967) and research on diglossias since have focused to a great extent, though not entirely, on characterizing various kinds of extended diglossias.

Post-1959 research on diglossia has concentrated on a number of variables and important questions: function, prestige, literary heritage, acquisition, standardization, stability, grammar, lexicon, phonology, the difference between diglossia and standard-with-dialects, extent of distribution in space, time, and in various language families, and finally what engenders diglossia and what conditions favor its development.

1.

Function. The functional differentiation of discrepant varieties in a diglossia is fundamental, thus distinguishing it from bilingualism. H and L are used for different purposes, and native speakers of the community would find it odd (even ludicrous, outrageous) if anyone used H in an L domain, or L in an H domain.

2.

Prestige: in most diglossias examined, H was more highly valued (had greater prestige) than was L. The H variety is that of `great' literature, canonical religious texts, ancient poetry, of public speaking, of pomp and circumstance. The L-variety is felt to be less worthy, corrupt, `broken', vulgar, undignified, etc.

3.

Literary Heritage: In most diglossic languages, the literature is all in H-variety; no written uses of L exist, except for `dialect' poetry, advertising, or `low' restricted genres. In most diglossic languages, the H-variety is thought to be the language; the L-variety is sometimes denied to exist, or is claimed to be only spoken by lesser mortals (servants, women, children). In some traditions (e.g. Shakespeare's plays), L-variety would be used to show certain characters as rustic, comical, uneducated, etc.

4.

Acquisition: L-variety is the variety learned first; it is the mother tongue, the language of the home. H-variety is acquired through schooling. Where linguists would therefore insist that the L-variety is primary, native scholars see only the H-variety as the language.

5.

Standardization: H is strictly standardized; grammars, dictionaries, canonical texts, etc. exist for it, written by native grammarians. L is rarely standardized in the traditional sense, or if grammars exist, are written by outsiders.

6.

Stability: Diglossias are generally stable, persisting for centuries or even millennia. Occasionally L-varieties gain domains and displace the H-variety, but H only displaces L if H is the mother tongue of an elite, usually in a neighboring polity.

7.

Grammar: The grammars of H are more complex than the grammars of L-variety. They have more complex tense systems, gender systems, agreement, syntax than L-variety.

8.

Lexicon: Lexicon is often somewhat shared, but generally there is differentiation; H has vocabulary that L lacks, and vice-versa.

9.

Phonology: Two kinds of systems are discerned. One is where H and L share the same phonological elements, but H may have more complicated morphophonemics. Or, H is a special subset of the L-variety inventory. (But speakers often fail to keep the two systems separate.)

A second type is one where H has contrasts that L lacks, systematically substituting some other phoneme for the lacking contrast; but L may `borrow' elements as tatsamas, using the H-variety contrast in that particular item.

10.

Difference between Diglossia and Standard-with-dialects. In diglossia, no-one speaks the H-variety as a mother tongue, only the L-variety. In the Standard-with-dialects situation, some speakers speak H as a mother tongue, while others speak L-varieties as a mother tongue and acquire H as a second system.

11.

Distribution of diglossia in language-families, space, and time. Diglossia is not limited to any geographical area or language family, and diglossias have existed for centuries or millennia (Arabic, South Asia). Most diglossias involve literacy, but oral diglossias are conceivable.

12.

What engenders diglossia and under what conditions.

(a)

Existence of an ancient or prestigious literature, composed in the H-variety, which the linguistic culture wishes to preserve as such.

(b)

Literacy is usually a condition, but is usually restricted to a small elite. When conditions require universal literacy in H, pedagogical problems ensue.

(c)

Diglossias do not spring up overnight; they take time to develop

These three factors, perhaps linked with religion, make diglossia extremely stable in Arabic and other linguistic cultures such as South Asia.