Persuasion v. Knowledge

I was most intrigued by the arguments between Scaevola and Crassus concerning the methods an uses of rhetoric by orators. I agree with Scaevola when he says "I can cite more instances of damages done, than of aid given to the cause of the state by men of first-rate eloquence..." (294) and I do not agree with Crassus when he says "For excellence in speaking cannot be made manifest unless the speaker fully comprehends the matter he speaks about" (296). Eloquence is something that is not dependent on knowledge (except of speaking persuasively). I think of the former CEO of the company my dad works for: the CEO was an excellent speaker and so traveled to conferences and gave speeches on their products (bio-medical devices) and my dad would always hold his breath in hopes that no one actually learned in science was in the audience because he lacked a basic understanding of terms and functions. However, he was almost always applauded and gained the company grants and donations despite his confusion. There's also the videos on Youtube where people are questioned about who they will vote for: the interviewer asks if they agree with such and such policies of either Obama or Romney, and the interviewees whole-heartedly agree with policies of the opposite candidate if only the name of the candidate they support is attached to it. This is because political speeches are nowadays (in my opinion) dependent on buzzwords that appeal to the masses and crafty phrasing with content geared towards the demonizing of the opponent with little relevance to actual issues. Therefore, an eloquent speech without knowledge of subject matter would not be "the sport of universal derision" (296) as Crassus says. I believe (through our readings) persuasion is much more dependent on the knowledge of the audience than the knowledge of the speaker and so persuasion only needs the orators knowledge of the audience. I enjoyed Book 1 the most because of the back and forth and the discovery through argument because it makes clear that no matter how knowledgeable you may be on a subject (in this case rhetoric) you will always find an opponent and so the most important thing is knowing the beliefs of your opponent and how you can use them to your advantage. Crassus' assertion that rhetoric is dependent on knowledge of the subject matter is obviously important, but is not the crucial point.