After finishing high school, he decided to pursue a scholarly career rather than a musical one. He enrolled at Columbia University in New York. In his senior year, he attended a class taught by Franz Boas on American Indian languages. With references from Boas and Ruth Benedict, he was accepted as a graduate student by Melville J. Herskovits at Northwestern University in Chicago. In the course of his graduate studies, Greenberg did fieldwork among the Hausa of Nigeria, where he learned the Hausa language. The subject of his doctoral dissertation was the influence of Islam on a Hausa group that, unlike most others, had not converted to it.
In 1940, he began postdoctoral studies at Yale University. These were interrupted by service in the U.S. Army Signal Corps during World War II, where he worked as a codebreaker and participated in the landing at Casablanca. Before leaving for Europe in 1943, Greenberg married Selma Berkowitz, whom he had met during his first year at Columbia.
After the war, Greenberg taught at the University of Minnesota before returning to Columbia University in 1948 as a teacher of anthropology. While in New York, he became acquainted with Roman Jakobson and André Martinet. They introduced him to the Prague school of structuralism, which influenced his work.
In 1962, Greenberg moved to the anthropology department of Stanford University in California, where he continued to work for the rest of his life. In 1965 Greenberg served as president of the African Studies Association. He received in 1996 the highest award for a scholar in Linguistics, the Gold Medal of Philology
Greenberg's reputation rests in part on his contributions to synchronic linguistics and the quest to identify linguistic universals. In the late 1950s, Greenberg began to examine corpora of languages covering a wide geographic and genetic distribution. He located a number of interesting potential universals as well as many strong cross-linguistic tendencies.
In particular, Greenberg conceptualized the idea of "implicational universal", which takes the form, "if a language has structure X, then it must also have structure Y." For example, X might be "mid front rounded vowels" and Y "high front rounded vowels" (for terminology see phonetics). Many scholars took up this kind of research following Greenberg's example and it remains important in synchronic linguistics.
Like Noam Chomsky, Greenberg sought to discover the universal structures underlying human language. Unlike Chomsky, Greenberg’s approach was functionalist, rather than formalist. An argument to reconcile the Greenbergian and Chomskyan approaches can be found in Linguistic Universals (2006), edited by Ricardo Mairal and Juana Gil .
Many who are strongly opposed to Greenberg's methods of language classification (see below) acknowledge the importance of his typological work. In 1963 he published an article that was extremely influential in the field: "Some universals of grammar with particular reference to the order of meaningful elements". Greenberg rejected the view, prevalent among linguists since the mid-20th century, that comparative reconstruction was the only tool to discover relationships between languages. He argued that genetic classification is methodologically prior to comparative reconstruction, or the first stage of it: you cannot engage in the comparative reconstruction of languages until you know which languages to compare (1957:44).
He also criticized the prevalent view that comprehensive comparisons of two languages at a time (which commonly take years to carry out) could establish language families of any size. He argued that, even for 8 languages, there are already 4,140 ways to classify them into distinct families, while for 25 languages there are 4,749,027,089,305,918,018 ways (1957:44). By way of comparison, the Niger–Congo family is said to have some 1,500 languages. He thought language families of any size needed to be established by some scholastic means other than bilateral comparison. The theory of mass comparison is an attempt to demonstrate what those means are.
Greenberg argued for the virtues of breadth over depth. He advocated restricting the amount of material to be compared (to basic vocabulary, morphology, and known paths of sound change) and increasing the number of languages to be compared to all the languages in a given area. This would make it possible to compare numerous languages reliably. At the same time, the process would provide a check on accidental resemblances through the sheer number of languages under review. The mathematical probability that resemblances are accidental decreases sharply with the number of languages concerned (1957:39).
Greenberg claimed that mass "borrowing" of basic vocabulary is unknown. He argued that borrowing, when it occurs, is concentrated in cultural vocabulary and clusters "in certain semantic areas", making it easy to detect (1957:39). With a goal of determining broad patterns of relationship, the issue was not to get every word right but to detect patterns. From the beginning with his theory of mass comparison, Greenberg addressed why the issues of chance resemblance and borrowing were not obstacles to its being useful. Despite that, critics consider those areas were shortcomings of the theory.
Greenberg first called this method "mass comparison" in an article in 1954 (reprinted in Greenberg 1955). As of 1987, he replaced the term "mass comparison" with "multilateral comparison", to emphasize its contrast with the bilateral comparisons recommended in linguistics textbooks. He believed that multilateral comparison was not in any way opposed to the comparative method, but is, on the contrary, its necessary first step (Greenberg, 1957:44). According to him, comparative reconstruction should have the status of an explanatory theory for facts already established by language classification (Greenberg, 1957:45).
Most historical linguists (Campbell 2001:45) reject the use of mass comparison as a tool for establishing genealogical relationships between languages. Among the most outspoken critics of mass comparison have been Lyle Campbell, Donald Ringe, William Poser, and the late R. Larry Trask. Greenberg is widely known for his development of a classification system for the languages of Africa, which he published as a series of articles in the Southwestern Journal of Anthropology from 1949 to 1954 (reprinted together as a book in 1955). He revised the book and published it again in 1963, followed by a nearly identical edition in 1966 (reprinted without change in 1970). A few further changes to the classification were made by Greenberg in an article in 1981.
Greenberg grouped the hundreds of African languages into four families, which he dubbed Afroasiatic, Nilo-Saharan, Niger–Congo, and Khoisan. In the course of his work, Greenberg coined the term "Afroasiatic" to replace the earlier term "Hamito-Semitic", after showing that racially based Hamitic, widely accepted since the 19th century, is not a valid language family. Another major feature of his work was to support the classification of the Bantu languages, which occupy much of sub-Saharan Africa, as a branch of the Niger–Congo language family, rather than as an independent family as many Bantuists had maintained.
Greenberg's classification rested largely in evaluating competing earlier classifications. For a time, his classification was considered bold and speculative, especially the proposal of a Nilo-Saharan languages family. Now, apart from Khoisan, it is generally accepted by African specialists and has been used as a basis for further work by other scholars.
Greenberg's work on African languages has been criticised by Lyle Campbell and Donald Ringe, who do not believe that his classification is justified by his data; they request a reexamination of his macro-phyla by "reliable methods" (Ringe 1993:104). Harold Fleming and Lionel Bender, who are sympathetic to Greenberg's classification, acknowledge that at least some of his macrofamilies (particularly Nilo-Saharan and Khoisan) are not fully accepted by the linguistic community and may need to be split up (Campbell 1997). Their objection is methodological: if mass comparison is not a valid method, it cannot be expected to successfully have brought order out of the chaos of African languages.
In contrast, some linguists have sought to combine Greenberg's four African families into larger units. In particular, Edgar Gregersen (1972) proposed joining Niger–Congo and Nilo-Saharan into a larger family, which he termed Kongo-Saharan. Roger Blench (1995) suggests Niger–Congo is a subfamily of Nilo-Saharan. Most American Indian linguists classify the native languages of the Americas into 150 to 180 independent language families. Some have thought two language families, Eskimo–Aleut and Na-Dené, were distinct, perhaps the results of later migrations into the New World.
Early on, Greenberg (1957:41, 1960) became convinced that many of the language groups considered unrelated could be classified into larger groupings. In his 1987 book Language in the Americas, while supporting the Eskimo–Aleut and Na-Dené groupings as distinct, he proposed that all the other Native American languages belong to a single language macro-family, which he termed Amerind.
Language in the Americas has generated lively debate, but has been strongly criticized; it is rejected by most specialists in indigenous languages of the Americas and also by most historical linguists. Specialists in the individual language families have found extensive inaccuracies and errors in Greenberg’s data, such as including data from non-existent languages, erroneous transcriptions of the forms compared, misinterpretations of the meanings of words used for comparison, and entirely spurious forms.
Historical linguists also reject the validity of the method of multilateral (or mass) comparison upon which the classification is based. They argue that he has not provided a convincing case that the similarities presented as evidence are due to inheritance from an earlier common ancestor rather than being explained by a combination of accidental similarity, errors, excessive semantic latitude in comparisons, borrowings, onomatopoeia, etc.
Selected works by Joseph H. Greenberg:
Studies in African Linguistic Classification. New Haven: Compass Publishing Company. 1955. (Photo-offset reprint of the SJA articles with minor corrections.)
Essays in Linguistics. Chicago: University of Chicago Press. 1957.
The Languages of Africa. Bloomington: Indiana University Press. 1963.
Language Universals: With Special Reference to Feature Hierarchies. The Hague: Mouton & Co. 1966.
Language in the Americas. Stanford: Stanford University Press. 1987.
Keith Denning; Suzanne Kemmer, eds. (1990). On Language: Selected Writings of Joseph H. Greenberg. Stanford, CA: Stanford University Press.
William Croft, ed. (2005). Genetic Linguistics: Essays on Theory and Method. Oxford: Oxford University Press.
"Synchronic and diachronic universals in phonology". Language. 42 (2):
Greenberg, Joseph H. (1970). "Some generalizations concerning glottalic consonants, especially implosives". International Journal of American Linguistics.
Greenberg, J. H. (1989). "Classification of American Indian languages: A reply to Campbell". Language.