Many things have contributed to archaeology becoming explicitly considered a field of cultural politics. The cultural changes associated with postmodernity (for example resurgent nationalisms feeding searches for local identity) and in particular the frequent referencing and appropriation of the archaeological past in heritage concerns are important factors. Archaeology has been brought forcibly to confront its place in the present by interests normally considered external to the academy. The philosophical and methodological challenges to value freedom in critical theory (qv Western Marxism) and ideology critique, and sociologies of knowledge which treat knowledges as cultural productions or achievements (qv constructivist philosophy of science) have made it impossible, in the view of many, to maintain a belief in archaeological knowledge as essentially neutral and finding its origin in a real past detached from the present. The concept of discourse is here central to a position which would have archaeology a mode of cultural production with accompanying inseparable political issues regarding the form, purpose and content of archaeological work.