The paper questions the need to reassess conceptual art in terms of old political debates. It proposes that the materialist/idealist dichotomy of 20th century philosophy might offer a basis on which to reconsider emerging political issues to which conceptual art might contribute. The work of Robert Smithson is examined in a new light, as an early practitioner of a conceptual environmental art. The methodological rigour and originality of the paper lay in its use of materialism and idealism as a new basis on which to catagorise this highly contentious body of work