what could be called an "abstraction hierarchy." For instance, Rudolf Carnap in his Introduction to Semantics (1942, Harvard University Press) writes: If… explicit reference is made to the speaker, or, to put it in more general terms, to the user of a language, then we assign it to the field of pragmatics. (Whether in this case reference to designata is made or not makes no difference for this classification.) If we abstract from the user of the language and analyze only the expressions and their designata, we are in the field of semantics. And if, finally, we abstract from the designata also and analyze only the relations between the expressions, we are in (logical) syntax. The whole science of language, consisting of the three parts mentioned, is called semiotic. (p. 9) A related statement was made a few years earlier by Carnap's fellow American philosopher Charles W. Morris, PhD student of the sociologist and pragmatist philosopher George Herbert Mead, and heavily influenced by the pragmatist and founder of (analytical) semiotics, Charles Sanders Peirce: "Syntactics, as the study of the syntactical relations of signs to one another in abstraction from the relations of signs to objects [i.e., semantics] or to interpreters [i.e., pragmatics], is the best developed of all the branches of semiotic." (p. 13) The relation between abstraction and Morris' influential trichotomy is a matter of ongoing discussion. Emic units A kind of abstraction commonly considered in linguistics is the phoneme, which abstracts speech sounds in such a way as to neglect details that cannot serve to differentiate meaning. Other analogous kinds of abstractions (sometimes called "emic units") include morphemes, graphemes and lexemes. References Linguistics Pragmatics