Relativism is the view that the meaning and value of human beliefs and behaviors is not absolute but dependent upon and can be understood and evaluated only in terms of, for example, their historical and cultural context. Philosophers identify many different kinds of relativism depending upon which classes of beliefs are said to depend upon what.
The concept is important to both philosophers and anthropologists, although in different ways. Philosophers explore how beliefs might or might not in fact depend for their truth upon such items as language, conceptual scheme, culture, and so forth; just one example is ethical relativism. Anthropologists, on the other hand, are concerned with describing actual human behavior. For them, relativism refers to a methodological stance in which the researcher suspends or brackets his or her own cultural biases while attempting to understand beliefs and behaviors in their local contexts. This is known as methodological relativism.
One advocate of relativism, Bernard Crick, a British political scientist, wrote "In Defense of Politics", arguing that moral conflict between people was inevitable, that it could only be resolved by ethics, and when that occurred in public the result was politics. Accordingly, the process of dispute resolution, harms reduction, mediation or peacemaking was central to all of moral philosophy. He was an important influence on the feminists and later the Greens.
An extremely common argument against relativism is an inherently contradictory (self-stultifying) notion: The statement "all is relative" is either a relative statement or an absolute one. If it is relative, then there must be some absolutes in the world. If the statement is absolute, on the other hand, then it provides an example of an absolute statement, proving that not all truths are relative.
The latter argument was one of the first things anybody ever said in reply to relativism, and needs more explanation.
See also
refuting relativism:
http://www.carm.org/relativism/relativism_refute.htm