Rhetoricians since Plato's day have been concerned with how much knowledge speakers should possess in order to speak effectively as well as ethically. The expert, like anyone, can err, but the chance of factual error decreases when speakers have a thorough grasp of their subject matter. However, the expertise position can potentially become a means of repressing public expression and quelling challenges to authority. Classical scholars Antonius, Sulpicius, and Gorgias did not require orators to possess specialized knowledge, while Plato and Crassus endorsed thorough education and training as a prerequisite to effective speech. Scaevola favored expertise as a requirement for speech, but believed such knowledge remains in the domain of field-specific specialization, not in the realm of oratory. Many modern dilemmas revolve around these same arguments. Physicians, for instance, are experts in their field, but their authority often goes unchecked by the public, and they often escape responsibility for their actions and medical developments. The public relations problems that surrounded the Three Mile Island incident stemmed from the inability of technical experts to agree with one another and to appease the public's need for reassurance and forthrightness. Such instances indicate that rhetoric should remain within the public or generalist realm, for when it retreats from public accountability, it becomes a tool for manipulation by an elite instead of a means of maintaining and reinforcing the human community. (Seventeen references are included.) (JC)