Use of the dialogue as a literary device made it easy for Plato not only to present his own position (in the voice of Socrates) but also to consider (in the voices of other characters) significant objections that might be raised against it. This doesn't mean that philosophy is merely an idle game of argument and counter-argument, he pointed out, because it remains our goal to discover the one line of argument that leads to the truth. The philosopher cautiously investigates every possibility and examines every side of an issue, precisely because that increases the chances of arriving eventually at a correct account of reality.
Thus, Simmias suggests that the relationship between the soul and the body may be like that between musical harmony and the strings of a lyre that produces it. In this case, even though the soul is significantly different from the body, it could not reasonably be expected to survive the utter destruction of that physical thing. (This is an early statement of a view of human nature that would later come to be called epiphenomenalism.) But Socrates replies that this analogy will not hold, since the soul exercises direct control over the motions of the body, as the harmony does not over those of the lyre. Plato's suggestion here seems to be that it would become impossible to provide an adequate account of human morality, of the proper standards for acting rightly, if Simmias were right.
Thus, Simmias suggests that the relationship between the soul and the body may be like that between musical harmony and the strings of a lyre that produces it. In this case, even though the soul is significantly different from the body, it could not reasonably be expected to survive the utter destruction of that physical thing. (This is an early statement of a view of human nature that would later come to be called epiphenomenalism.) But Socrates replies that this analogy will not hold, since the soul exercises direct control over the motions of the body, as the harmony does not over those of the lyre. Plato's suggestion here seems to be that it would become impossible to provide an adequate account of human morality, of the proper standards for acting rightly, if Simmias were right.