At the end of the twentieth century there has been a major cultural phenomenon: the rise of relativism as a social custom, practical facts and mentality. From a philosophical standpoint, relativism is the current of thought whereby human knowledge can not penetrate the reality itself, as Absolute, but must be content with grasping, only partial, particular, contingent and mutually conditional aspects of reality: it also recognizes the conditioning action of the subject on its objects of knowledge, doing just the saying of Protagoras "man is the measure of all things'".

As a result, relativism is a philosophical position that denies the existence of absolute truths, or puts into question critically the possibility of reaching their absolute and conclusive definition. In Europe it recognizes the first appearance in the Greek sophistry; later relativist positions were expressed by ancient and modern skepticism, by criticism, empiricism and pragmatism.

Relativism holds that absolute truth does not exist, or even if it existed, it can not be known or be expressed or, alternatively, can be known or expressed only partially (in fact, relatively). Individuals can therefore only get knowledge about, because every statement refers to particular factors and only in reference to them is true. For the Sophists, no cognitive act reaches the objective nature of things, nor is an absolute truth valid for everyone. Another point of view, is that since everything is filtered by human perceptions, limited and imperfect, inevitably all knowledge is relative to the experiences sensitive to humans.

As a result, relativism is a philosophical position that denies the existence of absolute truths, or puts into question critically the possibility of reaching their absolute and final definition. In Europe the first appearance was within the Greek sophistry; later relativist positions were expressed by ancient and modern skepticism, by criticism, empiricism and pragmatism.

Relativism holds that absolute truth does not exist, or, even if it existed, it could not be known or be expressed or, alternatively, could be known or expressed only partially (in fact, relatively). Individuals can therefore only get knowledge about, because every statement refers to particular factors and only in reference to them is true. For the Sophists, no cognitive act reaches the objective nature of things, nor is an absolute truth valid for everyone. Another point of view is that since everything is filtered by human perceptions, limited and imperfect, inevitably all knowledge is relative to the experiences sensitive to humans.

For the philosopher Nicola Abbagnano the ancient Sophists, skepticism, empiricism and criticism are manifestations of a relativism which tries to create a tradition. But actually relativism, for Abbagnano, was born as a modern phenomenon, linked to the culture of the nineteenth century. Extreme manifestation of the doctrine of Oswald Spengler in his book The Decline of the West (1918-1922) where he established the relativity of all values of life in relation to historical periods, considered as organic entities, each of which grows, it develops and He dies unrelated to the other:

"Every culture has its own criteria, the validity of which begins and ends with it. There is no universal human morality. "

Among the various civilizations it can not be any communication, since there are common values between them; so even Western civilization is therefore destined to disappear.

fact is that relativism is an abstract construction, which does not answer to the practical problems of life and civil society.

The argument whereby the only compass of human action – in his personal life - should be: “act according to your will”, without any serious reflection on the objective good of the person, is a thesis that seems to preserve individual freedom, but gives no response to natural desire of man for the infinite.

To the subjective reason of the Enlightenment has historically opposed the vision of a realistic reason, that is the "right reason”, the logos as a principle of interpretation of the universe.

This is a reason anchored to the principle of reality, which does not deny what can not be measured or explained, that is not closed to the spiritual dimension of man: the last step of reason is to recognize that there is an infinite number of things that are beyond it. One reason not "constructivist", but "cognitive" (does not want to create reality, but know it).

The realist reason recognizes that there are values, objective truths. The concept of "truth" refers not an abstract idea, but just the correspondence between knowledge and being, reality. The difficulty in defining the truth shows a limit of our capacity for knowledge, but may not lead to deny its very existence (otherwise it confuses the ontological level with the epistemological one).

Not even one can not deny the opportunity to tap into the truth, to know it, because this has an irreconcilable contradiction. In fact, those who claim that things are not knowable as they are, but only as they appear to know the difference between things as they are and things as they appear should know things as they really are, not just as they appear .. .

Even without entering in philosophical-logical path, we can see that the existence of truth - in different fields - emerges from our shared experience and from the evidence of reason.

This applies above all in the field of the truth of the facts, of the events. It can be difficult to rebuild them exactly; but the lie, slander, are always means to subdue, not to know and free.

The iconoclastic fury of relativism came even to question the existence of objective realities in the field of physical and natural sciences.

Popper said that science - despite having discovered that he could not say definitive certainties - progresses to the truth of nature trough increasing approximations.

As an example relevant to our daily lives: when we go to a doctor, we expect from him a diagnosis "true".

Recognizing the possibility of a “true” or objective" knowledge, because adherent with a certain approximation to reality, is not to say that there is a knowledge "complete" and "perfect".

Such an ability to tap into the truth about man with rational methods is found in the metaphysical sciences and humanities in which we identify the moral truths which are the constant component, universal, natural of values. The "law of Hume", the physicist claim that there is only one rational thought - the scientific one - able to reach objective knowledge, it has been disproved by the crisis of the traditional scientific thinking, which led science to open - still with rigor: reproducibility, falsifiability, etc. - to a plurality of methods, and to seek an ever greater interdisciplinarity.

Without going into details, we just remember that the same epistemologists, as Lakatos, have asked to overcome any foreclosure against metaphysics; that the harmony between scientific knowledge and other forms of knowledge is advocated by the scientists around the world.

Even in the humanities, the difficulty in defining a truth, the objective element of a value, does not mean to deny it. The identification of a truth, moreover, is not primarily determined by consensus, it cannot become purely conventional, as is the case for the regulation of the interest. In fact, if the interests are available, so it is not for the truth, which are the subject of knowledge, not of bargaining. If I have difficulty in defining the contours of human rights, I can not for this Without going into details, we just remember that the same epistemology, as Lakatos, have applied to overcome any foreclosure against metaphysics; that the harmony between scientific knowledge and other forms of knowledge is advocated by the scientists around the world.

Even in the humanities, the difficulty in defining a truth, the objective element of a value, does not mean to deny it. The identification of a truth, moreover, is not primarily determined by consensus, may not become a purely conventional, as is the case for the regulation of the interest. In fact, if the interest is available, so it is not for the truth, which are the subject of knowledge, not bargaining. If I have difficulty in defining the contours of human rights, I can not - for this – to step on, or 'fix them' according to my convenience!

The idea of truth, however, does not exclude the doubt, but rather requires, as a necessary tool to look for and recognize it, without stopping to apparent truth. Moreover, the idea of truth does not preclude freedom, indeed it makes it possible, because no choice can be truly free if it is not aware:

Man, placed in front of his limits, is constantly faced with the need to choose, then to give up something. We must defend human freedom to choose; but it is a deception the freedom not to choose, that is, to see fulfilled all claims.

The morality of acts is also defined by the relationship between human freedom and its true good. The deepest freedom, in fact, lies not simply in to "choose between this and that," in a superficial way. The deepest freedom is in determining oneself, his own life; but to make this possible, we must know the truth of their own lives.

Relativism, by denying to reason the ability to know the truth of man, cancels his freedom. "The distinction between yes and no, true and false, good and not, can be set aside unless the man does not want to set aside to be a man."