Kosuth belongs to a broadly international generation of conceptual artists that began to emerge in the mid-1960s, stripping art of personal emotion, reducing it to nearly pure information or idea and greatly playing down the art object. Along with Hanne Darboven and others, Kosuth gives special prominence to language. His art generally strives to explore the nature of art rather than producing what is traditionally called „art“. Kosuth’s works are frequently self-referential. He remarked in 1969:
„The ‚value‘ of particular artists after Duchamp can be weighed according to how much they questioned the nature of art.“
Kosuth’s works frequently reference Freud’s psycho-analysis and Wittgenstein ’s philosophy of language.
His first conceptual work Leaning Glass, consisted of an object, a photograph of it and dictionary definitions of the words denoting it. In 1966 Kosuth also embarked upon a series of works entitled Art as Idea as Idea, involving texts, through which he probed the condition of art. The works in this series took the form of photostat reproductions of dictionary definitions of words such as „water“, „meaning“, and „idea“. Accompanying these photographic images are certificates of documentation and ownership (not for display) indicating that the works can be made and remade for exhibition purposes.
One of his most famous works is One and three Chairs, a visual expression of Plato’s concept ofthe Forms. The piece features a physical chair, a photograph of that chair, and the text of a dictionary definition of the word „chair“. The photograph is a representation of the actual chair situated on the floor, in the foreground of the work. The definition, posted on the same wall as the photograph, delineates in words the concept of what a chair is, in its various incarnations. In this and other, similar works, Five Words in Blue Neon and Glass One and Three, Kosuth forwards tautological statements, where the works literally are what they say they are. A collaboration with independent filmmaker Marion Cajori, Sept. 11, 1972 was a Minimalist portrait of sunlight in Cajori’s studio.
In the early 1970s, concerned with his „ethnocentricity as a white, male artist“, Kosuth enrolled in the New School to study anthropology. He visited the Trobirands Islands in the South Pacific, and the Huallaga Indians in the Peruvian Amazon.
Hung on walls painted his signature dark gray, Kosuth’s later, large photomontages trace a kind of artistic and intellectual autobiography. Each consists of a photograph of one of the artist’s own older works or installations, overlaid in top and bottom corners by two passages of philosophical prose quoted from intellectuals identified only by initials.