Lieberman makes a few salient points in response to Blau’s paper on the historical periods of the Hebrew language. First, he objects to Blau skipping from Middle Hebrew directly to Modern Hebrew, implicitly privileging spoken over written language. While spoken language indeed precedes written, the written can often achieve an independent status that is important in its own right. Thus, for example, it seems that the language of the Responsa of Maimonides should have a place in the development of Hebrew.
Second, he appeals to the use of sociolinguistics to better draw the boundaries between chronological periods, in analogy to dialect geography. Thus dialect boundaries are drawn based on the loose clustering of isoglosses (Lieberman aptly remarks that such boundaries should not be considered walls, but “seives”). These clusters are the result of cultural and historical factors, such as language loyalty. Further, we should be aware that there are a variety of levels of language available to an individual for different social situations. Thus changes in language due to historical factors are often turned into cultural or sociolinguistic differences.
Often languages are differentiated not on linguistic but literary grounds. That is, major written works become the standard for a given period. This is reflected in the standard division of Pre-Biblical Hebrew, Biblical Hebrew, Dead Sea Scrolls Hebrew, Mishnaic Hebrew, etc. These works have a great influence on subsequent linguistic development, but they may also mask the greater linguistic diversity of a period.
Lieberman thus suggests a scheme in which Early Hebrew represents pre-Exilic Hebrew (ie pre-6th century, and leaving aside the earliest stages of Hebrew which are not documented directly). Judean or Post-Exilic Hebrew extends from the time of the Babylonian Exile until the time when Hebrew ceased to be spoken (c. 200 CE). Scholastic Hebrew covers the period until the revival of the spoken language in the 19th century, which he labels Israeli Hebrew.
Within Early Hebrew, he prefers to divide between a prose and a poetry dialect which shows archaic features, rather than distinguish a separate period of Archaic Hebrew. Thus it is a sociolinguistic rather than a historical distinction. Further, he suggests that Early Hebrew should also be divided into a southern Judean dialect, which became prominent, and a northern Ephraimite dialect.
In the next period, Judean Hebrew, he notes many sources of interference. Some of these are external to Hebrew, such as the influence of Aramaic, Persian, and later Greek and Latin. There also seems to be a situation of diglossia between a vernacular and a literary dialect which is reflected in later biblical books like Chronicles and Esther, as well as some compositions from the Judean Desert. The vernacular dialect is reflected in compositions which were originally oral within the Mishna, the Halakhic Midrashim, and other Tannaitic works.
In the Scholastic Period there were likewise two varieties of Hebrew in use: a dialect influenced by Early Hebrew, and the vernacular dialect as it was known from the Oral Law. Of course, there was again interference between the two, including the tendency to correct the vernacular to the more prestigious dialect.