“L’uomo It is the measure of all things, of those which are as they are and those that are not as they are not.”
We in Greece, around the fifth century a.c., the world philosophical and cultural rests on simple, but immovable pillars:
1. There is an exact match between thought /word/reality;
2. There is an unwritten law that affirms the existence of gods and can not be questioned;
3. there is a Truth absolute that you have to find out, reveal (In fact originally the term greek Aletheia means not hide, reveal).
For these axioms, l’uomo It is not the measure of all things, but there is an ultimate reality to investigate and discover. It is the ultimate reality that, in essence, It should be taken as Truth Absolute. The fact that we do not conform to it is due to ignorance (understood as lack of knowledge dell’Be).
Despite these beliefs adamantine , i Philosophy Greeks were faced with two dilemmas, that caused un'ingente existential suffering in spirit greco:
1. as many are born from the One?
2. how can there be becoming as it contrasts so strongly with the static of reason?
In the poem on the nature, Parmenides argues that the multiplicity and mutability world physical are illusory, and it affirms the reality of’Be unchangeable. Parmenides is considered one of the fathers of philosophy Greek. for the first time, He proposes a thought no longer founded on mythological explanations of the cosmos, but on a rational method, using the basic principle of logic formal, the principle of non-contradiction. From this principle it follows that a claim can not be false and true at the same time. In other words, means that if a statement is true, its negation must be necessarily false. Through the principle of non-contradiction, postulating that "Being and Non-Being is not" and, applying the principle of non-contradiction, Parmenides draws the following conclusions on Being:
1. Being is motionless because if moved would become subject to, and so now would, Now it would not be (remember the divergence with Heraclitus, where Being is seen as a movement of the pairs of opposites).
2. Being is One because it can not be two Beings: if one is being, what is not being necessarily non-being.
3. Being is eternal because there can be a time when it is no longer, or it is not yet.
Being is thus engendered and immortal, since in case contrary would mean not being: about birth would be, but not before birth; and the death would not be, or be only up to a certain point.
4. Being is indivisible, because otherwise it would require the presence of non-being (see item 2).
5. "And 'the same thinking and think that is. For without being ... you will not find the thought "
Consequently, from this point it follows that what is intended is also true. For what interests us here, we reached a key truth: Being and thinking coincide. What is thought is so real and existing. Only not be (that is, the anything), indeed, It can not be thought. Thought can not be fake, what defiles are the senses and subjective. Managing to curb the effect of subjective impressions on reason, this leads without the possibility of error to the understanding of reality.
The Sophists questioned the correspondence between thought, word and reality. Protagora States that "l’uomo It is the measure of all thingsʱ??. Il sophist here it does not mean a universal measure and shared, but a subjective measure that is only valid in view of the individual. Consequently, the single uomo becomes a measurement of each truth and each value and the human mind does not have access to an objective ultimate reality. It 'impossible to know the reality that lies beneath appearances. The reality for us is just the set of phenomena that make up our experiences. scientists and Philosophy They can not describe the world objectively. It is not possible to heal the divide between the sensations of different people. the truth It is therefore a time of subjectivity and not something there to which we must conform. then it falls on the role of philosopher which questing, discoverer and the ultimate reality. the truth It is to report every uomo established from time to time with the facts. Moreover, They also deny the fundamental principle of non-contradiction, discarding as irrelevant.
At this point, how can you choose the true discourse among many speeches?
The response of the sophist is that actually there is no true discourse, but they are all true and false in 'perspective of personal vision. All speeches (logos) have equal value truth ontologically, then the best speech is what convinces more. IS fine note that the sophists do not deny external reality, but only stipulate the unknowability of first principles. Gorgia will exacerbate the relationship between reality and knowledge claiming that the first principles: