At several points throughout the Platonic dialogues, the “learners paradox,” also known as “Meno's paradox,” is raised as the foremost problem any epistemological investigation must face. “How,” it queries, is learning possible if one does not know to begin with what one must learn?” (Meno, 80d). Whatever solutions have been offered since Plato's time, and whatever their merits, the paradox remains in the background of any discussion of how we acquire knowledge. Indeed, one might even say that the paradox does not merely present a problem in its own right, but rather in its own way expresses the most fundamental problem that all investigation of this sort faces: how is it possible for us to come to know the world in the face of the chasm that exists between our sensory experience and our knowledge? According to the paradox, we do not know reality, yet somehow seem to be capable of coming to know it; how can our sensory experience be any help at all to us in this endeavor if we do not already know what we seek? Unlike later philosophers, Plato and Aristotle, do not try to solve this problem by denying our ability to come to know reality: rather, they affirm despite all odds that there is a reality which exists independently of us which we can somehow come to know. Thus, if the learner's paradox really is as fundamental and problematic as it seems, judgment of either philosopher's epistemology will at some point find it necessary to examine how well they provide an answer to this puzzle.
The model for acquisition of knowledge implicit in Plato's Phaedo is in certain respects remarkably similar to Aristotle's. The discussion midway through the dialogue of the “Theory of Recollection” assumes, just as Aristotle does, that knowledge of the reality of things is reached through sensory experience of particulars through which one is able to abstract universal truths. “Surely,” Socrates remarks, “this conception of ours derives from seeing or touching or some other sense perception, and cannot come into our mind in any other way” (Phaedo, 75a). Likewise Aristotle observes that men “by nature desire to know” and thus take “delight. . .in [their] senses” which allow them to acquire knowledge (Metaphysics, I,1).
Beyond this core similarity, however, there are many obvious discrepancies between the arguments, most notably the language of recollection present in Plato but absent in Aristotle. For Socrates, it is important that his epistemology retain this language, at least in the Phaedo, because his argument is in the first place trying to prove the immortality of the soul. Thus one central motivation for using this language turns out to be incidental to Plato's actual view of the soul's learning process. But there nonetheless must be more compelling reasons to preserve this manner of speaking, as it is a common thread of multiple dialogues (Phaedo, Meno, and Phaedrus, for example), becoming, at least apparently, characteristic of Plato's philosophy. This more compelling reason is his need to answer the learner's paradox. According to a literal reading of the texts, Plato's solution to this conundrum is to deny that there is anything at all that we do not know. “There is nothing” Socrates claims, “that [the soul] has not learned”; all knowledge is present in the soul by virtue of its long experience and many reincarnations (Meno, 81c). Our seeming ignorance on earth is merely the result of our immortal soul's descent into a body, a material object which so muddles and confuses it that it forgets all its certain knowledge at birth. The solution to the paradox is in essence then, a claim that we both know and do not know everything we will experience. As a soul alone we know the forms of all things, but as a human being, we must struggle through possibly misleading sensory experience to “recall” that which we have now forgotten.
This solution is unthinkable for Aristotle. His hylomorphic view of the human person is central in his philosophy, and the belief that the soul is the form of the body makes recollection from a pre-corporeal existence is impossible. At a time when there was no body, there could have been no soul existing separately and possessing knowledge in its own right as a substance independent of the body. However, if Aristotle must reject Plato's solution, his theory of learning is faced afresh with the problem of the paradox. Nonetheless, we have examined Plato's solution only in a literal sense thus far. As it will turn out, there is a way of interpreting Plato's epistemology which brings it even closer to Aristotle's, and this reconciliation may perhaps prove useful in directing our approach to determining whether Aristotle's philosophy can present a viable solution to the learner's paradox.
Plato's literal solution relies exclusively upon the language of recollection, yet evidence from Phaedrus points to another possible interpretation of how we can understand recollection to begin with. Though he uses the image of a person remembering what he has known in a pre-corporeal state in both Meno and Phaedo to clarify his point, in Phaedrus Plato presents the object of “recollection” as “the Idea, a unity gathered together by reason” (Phaedrus, 249c). In other words, recollection perhaps is not so much remembering as the ability to recognize a thing according to its place in the universal sum of knowledge by means of the logical apparatus and capacity to recognize truth which are in man by nature. Phrased this way, in admittedly non-Platonic language, the position reveals its similarity to Aristotle's. Aristotle understands the mind as the sum of all knowledge, a concept remarkably similar to Plato's “unity gathered together by reason”. He even goes so far as to call it “the place of forms”, the forms being both for him and for Plato, the truly knowable aspect of a being (De Anima, III,4). The mind is, moreover, the single aspect of the soul which lives on after death, a point which recalls Plato's assertion that the soul, the proper knower of all things, is immortal (De Anima, II,2). Thus the two philosophers agree that the soul is the true location of all knowledge and that the soul understood in this sense is immortal: Aristotle's epistemology does not differ from Plato's in these respects, at least. Though this has taken us a long way towards reconciling the two epistemologies however, it turns out that it does not really solve our initial problem. In order to effect this reconciliation, I had to employ essentially Aristotelean language to explain Plato's position. Only when the language of potentiality and actuality is introduced and applied to this statement does it begin to sound like the full solution Aristotle's ideas can lead us to.
Aristotle's introduction to Western thought of the distinction between actuality and potentiality is the single major difference between the two philosophers that I will address here. Meno's paradox presupposes that we can be in only two states with respect to our knowledge of a given thing: one of positive knowledge or one of complete ignorance and unfamiliarity. Plato points towards Aristotle's solution by presenting a sort of “third manner” of knowing: knowing perfectly in the soul while the human person as a whole knows imperfectly but can recollect the knowledge of the soul given sufficient help. Applied to the learner's paradox, Aristotle's theory of knowledge takes the idea of a “third way” even further. All human beings, he says, are fully capable of knowing all truth. That is, we by nature are innately receptive of truth: we have the intrinsic ability to receive truth when presented with it, even if not previously knowing it in action. Actual knowledge may be absent, but it is absent in such a way that when presented with it, we are able to tell what it is and where it belongs. This is a round about way of expressing the idea that all knowledge of truth “is present”—though such language is inadequate to express the nature of potentiality—potentially in our souls. Acquisition of knowledge is simply actualization of this potential.
Thus, we see that Plato can be read as pointing towards a theory of knowledge that Aristotle later develops by introducing the distinction between actuality and potentiality. Though we cannot accept Plato's original model of the soul as a separate, all-knowing entity whose knowledge we remember over the course of a muddled lifetime if, like Aristotle, we want to preserve the idea that the soul is the form of the body, the alternate interpretation of Plato hints at Aristotle's resolution of this difficulty by altering our understanding of what recollection consists of. Knowledge is in some sense “in” the mind for Aristotle as well as for Plato. The literal answer to the learner's paradox—that we know all things anyway because our soul has already encountered them—must be discarded in light of the Aristotelean understanding of the human person. However, in establishing the language of potentiality and actuality, Aristotle in turn can provide a resolution to the problem of how to gain knowledge by expressing our potential to receive knowledge as our means of “knowing” what we don't know, and therefore as the grounds for its eventual drawing out and actualization.