The situation in the "Protagoras" and the work between Plato and The Protagoras is the first major dialogue regarding the date of composition. The literary skill and expertise expressive do that is made, however, very unlikely the assumption of some scholars, as Von Arnim, Ritter, Wilamowitz- it was the oldest of all the dialogues of Plato, written by Socrates was still alive. But clearly it is a work of the first production time of Plato, one of the "Socratic dialogues" writing prior to the first trip to Sicily. Shares indeed clearly display a series of dialogs with this initial period, with the shorter dialogues we consider somewhat earlier. Socrates image seems to respond completely to what we believe characteristic the historical Socrates, engaged in ethical issues, interested in "Inductive reasoning" (as Aristotle says), without metaphysical doctrine, without any theory of Ideas (Oregon State, n.d.). Moreover, the raised discussion concludes, as in other minor dialogues, without have found a valid response, and is used only aporetic end to show the alleged failure of the partners know and that Socrates invites us to continue in the effort to find the definition of virtue, to persist in the question.
Pros
Protagoras stated in the change in constant flux, therefore, it should begin to play the sophist, on the ontology. The philosopher of Abdera is conceived as something in motion, as a constant flux: the changing realities, multiform, plural, and submerged in the river of Heraclitus.
In this conception ontological philosophy supports all Protagorean and becomes valid. Thus, from the outset, we find something crucial: the radical separation between the thought of Plato, still based on the ontology of Parmenides, and the thought of Protagoras, which found a strong empathy with the philosopher of Ephesus.
"It was the first (Protagoras) to say that about any subject are two possible opposing views with each other".
"Protagoras also holds that man is the measure of all things, of which they are as they are and are not as they are not"
Of these two sentences is possible to deduce the foundation Protagorean: the logic of relations. With the first sentence refers to the anti-logical principle, Protagoras shows that things are not in themselves but they are in relation to something (Mintz, 2009), i.e. that there is no absolute, unique, unchanging, justice, goodness or how small are not universal and absolute realities. However, something can be good for certain people (animals, plants or things) while others do not, e.g. the wood from cracking, weak or corrupt, it is good for the carpenter but bad for others. And even for the same people something can be good in certain circumstances and may not be in others, e.g. rain is good in times of drought but not in times of severe winter. In the same way an elephant can be very large relative to the size of the man, but extremely small relative to the planet. Then it can be said that the elephant alone is big or small, or ...