Since most of Isocrates rhetorical theory is scattered throughout Against the Sophists and Antidosis, it seems appropriate at this point to summarize the basic theories he expresses in these works:
1. Speech distinguishes men from animals, and makes possible all of civilization.
2. Rhetoric is an art, not a science.
3. A speaker's education should be extensive, not specialized, and should include a study of philosophy.
4. Morals cannot be taught, but study of political discourse will encourage the emulation of good citizens.
5. Orators who discourse on the general welfare are better even than law-givers, for the former have the higher task.
6. Speeches of orators should emphasize justice and virtue.
7. Public opinion can be swayed by the speaker; it does not of itself always tend toward virtue or justice.
8. Natural aptitude is essential to an orator; a man without natural aptitude can become an adequate speaker, but not a great one.
9. Some untaught men have become good orators, but the best orators are those who combine ability with training.
10. Both man's physical and mental faculties ought to be developed. Furthermore, they should be developed by the same methods; thus practical exercises in speaking are necessary to achieve artistry.
11.Voice and assurance are necessary to success in oratory.
12.Students must learn every kind of discourse, not merely one specialized one.
13.Each speech and its parts must be suited to the particular occasion; the same speech might not suit another man.
14.There are as many kinds of prose as there are kinds of poetry.
15.Political discourse cannot be learned by rote, but must be learned and practiced as an art.