I've been reading and rereading some Plato recently for a paper I'm scheduled to present in May on the rhetoric of Augustine's De Magistro.
De Magistro is a dialogue between Augustine and his young son. Its main topic is singular, yet the discussion covers several important topics. The main topic is teaching/learning and asks the question of whether or not anyone can teach someone else, and, conversely, whether we can learn anything from someone else. The reason Plato is important is because he brings up the same question in his dialogue entitled, Meno.
Plato and Augustine both conclude that, insofar as knowledge is concerned, we do not learn from others. Plato thinks we learn from ourselves, that is, from our eternal soul's own recollection of forgotten truth. Augustine concludes that it is Christ Himself who illuminates our minds to know.
The example in Meno is of a young slave. Socrates asks the slave boy, who has never been taught geometry, to answer a geometrical question. At first the boy gets the answer wrong, but eventually, though Socrates continual questions and drawings in the sand, the boy arrives at the correct answer. Many folks disagree with Plato because they think Socrates is teaching the boy by means of his verbal cues, or leading questions. However, Augustine's dialogue shows why this is not the case.
For Augustine, the discussion turns on the nature of signs. How can one teach another about something which the other does not know? If he does not know it, how can he come to know out of his ignorance? And if he does know it, how can he be taught what he already knows? One example is that of walking. If one is standing still, one might be able to teach another what is walking by taking a few steps, say ten. However, the observer might mistakenly conclude that walking is precisely the taking of ten steps, rather than the measured motion of striding with the legs. Alternatively, if both people are already walking, one cannot demonstrate to the other what walking is, because he is already doing it. If he walks faster, the observer may conclude that "hurrying" is the same thing as walking, although the two actions are distinct.
We could use signs to demonstrate what is walking. We could, for example, use words to provide a definition. But, since the signs themselves have no direct relationship to the thing itself (the letters w-a-l-k-i-n-g are not part of what actually is walking), the person cannot come to know walking simply by virtue of the signs. Rather, he must know what walking is in order for the signs to be intelligible.
So if a demonstration does not convey knowledge, and signs, in themselves, cannot convey knowledge, how is knowledge conveyed? One answer, provided several hundred years after Augustine, is referred to as Occasionalism. It has several interpretations, but the idea is basically that all instances where learning occurs (that "ah ha!" moment that comes in circumstances where we see a demonstration or hear a definition given) are simply the occasions that God decrees that we come to know X truth. Malebranche was the noted founder of Occasionalism, which he formulated as an solution to Descartes' mind/body dualism. Jonathan Edwards is also sometimes associated with occasionalism.
However, one need not be an occasionalist in order to accept Augustine's conclusion. To argue that Christ is the only Teacher who illuminates all minds to know the truth is not to argue for a specific method by which Christ accomplishes this fact. The simplest view may be occasionalism, however. It certainly does remove all pretense of human autonomy in the realm of knowledge!
For the Christian, it also harmonizes well with the basic truths of God's nature as eternal. To be eternal and rational is by definition to be omniscient, since anything that thinks and is eternal has thought every truth. That God knows all truth and thinks all truth is simply to acknowledge that truth is the sole possession of God. When men arrive at truth, there is a temptation to take pride in its acquisition. Contemporary belief even argues that we create our own truths. In a previous age, most men thought that a proper understanding of truth is that it is discovered. The keenest insight for the Christian, however, is that all truth is revealed, for it is not simply "out there" waiting to be discovered, but is the possession of God--a possession which God must give according to His good pleasure to whom He will, at what point in time that He will.
That an unbeliever would come upon something true should surprise us no more than that a believer may be deceived by falsehood. God has His own agenda for revealing the Truth, and He often humbles the elect and condemns the reprobate by withholding and revealing knowledge respectively. It is humbling to the elect, for he is driven to realize his complete dependency upon God for all that he must know. It is condemning to the reprobate, because no matter how much truth God reveals to him, saving knowledge remains undisclosed, and his rebellious beliefs only make him, in his understanding of any truth, more culpable before the God who possesses and discloses that truth.