Objections to relativism

a. Relativism is Self-Refuting
A doctrine is self-refuting if its truth implies its falsehood. Relativism asserts that the truth-value of a statement is always relative to some particular standpoint. This implies that the same statement can be both true and false. The qualification that the statement is true relative to standpoint A but false relative to standpoint B may save relativism from the charge of embracing gross contradictions. But it still clearly implies that relativism itself is false, at least relative to some standpoints. One might say that it is just as much false as it is true, in which case there seems to be no good reason to prefer relativism to alternative positions such as realism.
One possible response to this objection would be to modify the theory and hold that all truths are relative except for the truth that all truths are relative. On this view, the relativist thesis enjoys a unique status, being true in some non-relativistic sense. This position may be coherent, but it is rather implausible. It is hard to see what could justify granting the thesis of relativism this exceptional status. A more plausible option is for relativists to concede that their view is false relative to at least some non-relativistic theoretical frameworks but to deny that this admission is damaging. Relativism, they can claim, is simply in the same situation as any other theory. The theory of evolution is true from the perspective of modern science and false from the perspective of Christian fundamentalism. Relativists deny that one of these perspectives is demonstrably better than the other. But this does not mean that they cannot affirm the scientific perspective, and do so for cogent reasons. In the same way, they can acknowledge that relativism is false from the standpoint of metaphysical realism; but they can do this without inconsistency or incoherence since they are not metaphysical realists, and they have reasons for preferring relativism to realism.
A variation on the charge that relativism is self-refuting is the argument that it is somehow self-refuting for relativists to assert or to argue for their position. This line of attack has been pressed forcefully by Hilary Putnam and others. Putnam's argument is that ordinary rational discourse presupposes a non-relativistic notion of truth. Jûrgen Habermas offers a similar sort of argument in his critique of postmodernists like Foucault and Derrida, claiming that a commitment to truth, like a commitment to sincerity, is a necessary condition of successful communication.
Relativists, however, are likely to remain skeptical about these alleged presuppositions and implicit commitments. It may be true that when we engage in rational discourse we implicitly commit ourselves to the truth of what we are saying. But it is not at all obvious that we implicitly commit ourselves to a non-relativistic conception of truth. And even if this were the case, it is not clear why this supposed presupposition of everyday communication should be accorded so much respect and made the basis for a philosophical account of truth. Our everyday notions of space and time may also be non-relativistic, but we do not demand that physicists' theories of space and time conform to our pre-scientific ideas.
b. Relativism has Pernicious Consequences
This criticism also was first ventured by Plato and continues to be endorsed by many. Cognitive relativism is thought to undermine our commitment to improving our ways of thinking rather as moral relativism is thought to undermine our belief in the possibility of moral progress. Several reasons have been given to support this anxiety. To some, the fact that relativism countenances the possibility of multiple true but incompatible points of view entails a kind of epistemic nihilism. If creationism and the theory of evolution, Ptolemaic and Copernican astronomy, astrology and modern psychology are all equally true, then what purpose is served by developing new scientific theories? All views are of equal value, so why not just rest content with whatever happens to be "true for us"?
Against this, relativists can offer two responses. First, truth is not the only epistemic value. We can also prefer theories on the basis of such values as coherence with our other beliefs, predictive power, and practical fruitfulness. Second, by endorsing relativism one does not lose the right to judge beliefs according to their truth or falsity. Modern relativists will believe that the earth orbits the sun and that Copernicus' discovery represented scientific progress over earlier astronomy. But their philosophical account of the status of these beliefs will be relativistic. The Copernican theory is true and its acceptance represents progress according to the values and concerns that constitute the modern scientific standpoint—a standpoint shared by both relativists and non-relativists. The difference between them is that the relativists do not believe this standpoint can be proved superior to others except by arguments that are essentially circular and question-begging.
Hillary Putnam presses a slightly different version of the above objection. Relativism, he argues, tries to "naturalize" the concept of reason. What he means is that relativists try to discuss questions of truth, knowledge, and rationality in a thoroughly descriptive, non-normative way. Like social scientists afraid of allowing value-judgments to creep into their work, they take a detached stance and simply report the epistemic customs and practices of different cultures, eschewing any impulse to endorse or criticize them. And this amounts, in Putnam's words, to "mental suicide". For, while particular norms of rationality will be entrenched within a particular culture, reason has an inalienable critical or transcendent function which can be used to criticize existing epistemic norms. Relativism can thus be accused of encouraging a certain kind of intellectual passivity.
Relativists have also been accused of embracing determinism, and certainly thinkers like Nietzsche and Foucault sometimes invite this charge. The epistemic norms of a culture or a period are taken to be shaped by non-rational forces such as class interests, technology, or the will to power of a group or individual. And what people then come to believe is seen as a function of these norms. For example, Foucault suggests that the classification of homosexuality as a disease results from employing a certain kind of theoretical framework, one that posits a sharp distinction between the natural and the unnatural and correlates the former with the healthy, the latter with the sick. And this framework becomes established because it serves certain interests. So truth is identified with what is believed to be true, and what is believed to be true is determined by larger social forces operating within a culture or historical epoch.
This deterministic tendency, like the attempt to naturalize reason, is held by critics to entail, or at least encourage, a renunciation of the longstanding project of using reason to criticize existing norms, beliefs, and practices in order to furnish ourselves with better ones. Relativism is thus associated with the counter-Enlightenment aspects of postmodernism. But association is not the same thing as logical entailment. It may well be true that some relativists are drawn towards determinism or feel they must eschew value judgments. But it is not clear that these tendencies must be part of a relativistic outlook. Other relativists will argue that the connection between relativism and determinism, say, is historical and contingent rather than logical and necessary. In their view, one can consistently endorse a relativistic view of truth while still being committed to the relative superiority of some views over others, to the value of critical reflection, and to the possibility of using reason as an instrument of scientific and social progress.