New York Dada known and controversial across the New York, as well as American in general, art scene. His personality was equally intoxicating as his art; according to Richter, "Duchamp's attitude is that life is a melancholy joke, an indecipherable non-sense, not worth the trouble of investigating. To his superior intelligence the total absurdity of life, the contingent nature of a world denuded of all values, are logical consequences of Descartes' Cogito ergo sum." Most famous amongst the works created by Duchamp in the New York period were his ready-mades, particularly the piece entitled "Fountain". During his time in New York he maintained
Cogito, ergo sum and that "I" know what "thinking" is. He suggested a more appropriate phrase would be "it thinks" wherein the "it" could be an impersonal subject as in the sentence "It is raining." The Danish philosopher Søren Kierkegaard calls the phrase a tautology in his "Concluding Unscientific Postscript". He argues that the "cogito" already presupposes the existence of "I", and therefore concluding with existence is logically trivial. Kierkegaard's argument can be made clearer if one extracts the premise "I think" into the premises "'x' thinks" and "I am that 'x'", where "x" is used as a placeholder in order to disambiguate