All art (after Duchamp) is conceptual (in nature) because art only exists conceptually.
Joseph KosuthPhotography, as an invention, was both art and science. The view it gave us of the world was in some measure acceptable because it was a product of our vision of the world; and it did so as part of the same process which seemed to impart 'truth': science.
Joseph KosuthI liked that the work itself was something other than simply what you saw It meant you could have an art work which was that idea of an art work, and its formal components weren't important.
Joseph Kosuth