Vico claims that the aim of philosophy is the problem of "finding," and he identifies the theory of "finding" with "topical philosophy.” … - Ernesto Grassi

If philosophy aims at being a theoretical mode of thought and speech, can it have a rhetorical character and be expressed in rhetorical forms? The answer seems obvious. Theoretical thinking, as a rational process, excludes every rhetorical element because pathetic influences—the influences of feeling—disturb the clarity of rational thought. … To prove means to show something to be something, on the basis of something. To have something through which something is shown and explained definitively is the foundation of our knowledge. Apodictic, demonstrative speech is the kind of speech which establishes the definition of a phenomenon by tracing it back to ultimate principles, or archai. It is clear that the first archai of any proof and hence of knowledge cannot be proved themselves because they cannot be the object of apodictic, demonstrative, logical speech; otherwise they would not be the first assertions. Their nonderivable, primary character is evident from the fact that we neither can speak nor comport ourselves without them, for both speech and human activity simply presuppose them. But if the original assertions are not demonstrable, what is the character of the speech in which we express them? Obviously this type of speech cannot have a rational-theoretical character. ...
Basic premises cannot have an apodictic, demonstrative character and structure but are thoroughly indicative. ...
Arche … cannot have a rational but only a rhetorical character. Thus the term "rhetoric" assumes a fundamentally new significance; "rhetoric" is not, nor can it be the art, the technique of an exterior persuasion; it is rather the speech which is the basis of the rational thought.

We are forced to distinguish between three kinds of speech: (1) The external, “rhetorical speech,” in the common meaning of this expression, which only refers to images because they affect the passions. Since these images do not stem from insight, however, they remain an object of opinion. This is the case of the purely emotive, false speech: “rhetoric” in the usual negative sense. (2) The speech which arises exclusively from a rational proceeding. It is true that this is of a demonstrative character, but it cannot have a rhetorical effect because purely rational arguments do not attain to the passions, i.e., “theoretical” speech in the usual sense. (3) The true rhetorical speech. This springs from the archai, nondeductible, moving, and indicative, due to its original images. The original speech is that of the wise man, of the sophos, who is not only epistetai, but who with insight leads, guides, and attracts.

In the second part of the Phaedrus Plato attempts to clarify the nature of “true” rhetoric. … it does not arise from a posterior unity which presupposes the duality of ratio and passio, but illuminates and influences the passions through its original, imaginative characters. Thus philosophy is not a posterior synthesis of pathos and logos but the original unity of the two under the power of the original archai. Plato sees true rhetoric as psychology which can fulfill its truly “moving” function only if it masters original images [eide]. Thus the true philosophy is rhetoric, and the true rhetoric is philosophy, a philosophy which does not need an “external” rhetoric to convince, and a rhetoric that does not need an “external” content of verity.