Mikołaj Habdank Kruszewski, (Russianized, Nikolay Vyacheslavovich Krushevsky, Никола́й Вячесла́вович Круше́вский) (December 18, 1851, Lutsk – November 12, 1887, Kazan[1]) was a Polish linguist active in the Russian Empire, most significant as the co-inventor of the concept of the phoneme. From 1883, he was a professor at Kazan University. His notable works include On Sound Alternation (1881) and Outline of Linguistic Science (1883). The former is the introduction to his master's thesis on morphophonemic alternation in Old Slavic (the section focusing on the theoretical background for the empirical work in the body of the thesis) and the latter is his doctoral thesis.
A student of Jan Baudouin de Courtenay (1845–1929), Kruszewski worked with Baudouin de Courtenay to develop the linguistics associated with the Kazan school. These inspired other linguists. Since it is difficult to distinguish who created which concept, the systematic alternation treatment may be attributed to both. Their innovative and highly influential work was acclaimed by Roman Jakobson only about a hundred years after his time.
Kruszewski studied in the historical-philological faculty in Warsaw, teaching the Russian language to support himself. Desiring broader experience, he went to Kazan, where he met Baudouin de Courtenay. He was a hard-working and ambitious student. He became full professor in Kazan in 1885, aged 34, having prepared two theses. Unfortunately his brilliant career was dramatically cut off by a grave neurological and mental illness; he had to retire the same year and died in 1887.
Kruszewski's major work was in the theory of alternations. He was one of the first to create a modern systematic approach to the phonological structure of language. Above all, Kruszewski was preoccupied with classifying the alternations and describing their status.
Kruszewski proposed three types of alternations and stressed the fact that each alternation is influenced by two important factors. The first factor involves the changes sounds undergo within themselves, while the second involves the conditions that stimulate a given change. Such an approach results in the classification of alternations into three major groups.
The first category of alternations is restricted to the sounds that are very similar. Alternations that belong to this category are governed by four rules:
An example of the first type are those variations between particular sounds in Russian as a function of the palatalization of the preceding consonant.
The alternations that represent the second and third categories are quite similar and there are three important conditions under which the alternations take place:
The sounds involved in alternations of the sounds of the second and the third category are known as correlatives. The only difference between the second and the third category is the degree to which a given category is morphologized. Kruszewski's example for the second category is u-umlaut in Icelandic. He does not strictly separate the second and the third category.