Further criticisms have been levelled at functionalism by proponents of other social theories, particularly conflict theorists, Marxists, feminists and postmodernists. Conflict theorists criticized functionalism's concept of systems as giving far too much weight to integration and consensus, and neglecting independence and conflict. Lockwood, in line with conflict theory, suggested that Parsons' theory missed the concept of system contradiction. He did not account for those parts of the system that might have tendencies to mal-integration. According to Lockwood, it was these tendencies that come to the surface as opposition and conflict among actors. However Parsons thought that the issues of conflict and cooperation were very much intertwined and sought to account for both in his model. In this however he was limited by his analysis of an ‘ideal type' of society which was characterized by consensus. Merton, through his critique of functional unity, introduced into functionalism an explicit analysis of tension and conflict. Yet Merton's functionalist explanations of social phenomena continued to rest on the idea that society is primarily co-operative rather than conflicted, which differentiates Merton from conflict theorists.