QQC 1: 5/17

Quote: "And so the rhetorician's business is not to instruct a law court or a public meeting in matters of right and wrong, but only to make them believe; since, I take it, he could not in a short while instruct such a mass of people in matters so important." (pg. 92)

Question: If the rhetorician's business consists of only making others believe between right and wrong, how does this alter the possibility of finding out the "truth"? Is there actually a set definition of right and wrong, or does it vary based on the beliefs of others and the influences that surround them?