In the context of the restoration of Athenian democracy in the 4th century BCE, Isocrates and Plato established two of the most prominent philosophical schools of antiquity and certainly the two most important ones of the Classical Period. To some extent influenced by Socratic morality focused on the debate of virtues, both were radical opponents of the sophists of their time and the previous century, who, according to them, promoted an eristic education that is sometimes immoral and sometimes flattering. With the aim of offering new pedagogical alternatives for the political formation of the youth, both Isocrates and Plato propose, under the label of philosophia, models of paideia oriented towards the common good, justice, and integrity. However, there is a fundamental ideological dispute surrounding each of these philosophies. In order to oppose sophistic rhetoric, the idealism of Platonic philosophy, as we know, employs the dialectical method so that true knowledge (episteme) of moral virtues can be attained, thus promoting justice and the common good of the polis. Isocratic pragmatism, on the other hand, outlines philosophy as a paideia of civic discourse (logoi politikoi), in which only good opinions (doxai) would be capable of better guiding the city with reasonableness for the actions to be taken, to the detriment of Platonic episteme which would serve no purpose for politics. Therefore, we will discuss these and other aspects of this ideological dispute between Isocrates and Plato, seeking to verify how this quarrel occurs throughout the texts attributed to them, as well as to point out to what extent the relationship between their philosophical doctrines was determinant for the contours of Philosophy and Rhetoric in posterity. [ABSTRACT FROM AUTHOR]