Conflict is a basic process in social life and can be both destructive and cohesive. In some situations, it can be destructive for some groups and act as a cohesive force for others. Racial and ethnic groups may be the source and the result of the two faces of social conflict, acting as a boundary marker between groups that see themselves as distinctive in their interests and values from other such groups. Since the mid-twentieth century, sociologists have grappled with a variety of perspectives on conflict that have emphasized various aspects of the destructive and the integrative nature of the process. Functional theorists have tended to downplay the purely negative forces, while conflict theorists have tried to establish the central role of conflict as a means to challenge the status quo and bring about fundamental social change. Several attempts have also been made to refine and integrate the two approaches, pointing to the functions of social conflict or to elements of consensus and equilibrium found in both models.