Meno's Paradox in Plato's Meno, Its Dilemma, and Polanyi's Concept of Tacit Knowledge
Meno's Paradox and the Theory of Recollection (Plato's Meno)
In Plato's dialogue Meno, there is a famous problem known as "Meno's Paradox" (the paradox of inquiry). Meno says to Socrates: "A person cannot inquire about what they know—there's no need—and they cannot inquire about what they don't know—they don't know what to look for." In other words, "if you don't know, you can't ask (because you don't even know what you don't know), and if you know, there's no need to ask"—this is the dilemma. This paradox succinctly demonstrates the epistemological puzzle of how we can learn unknown things. Plato presents his unique solution, the "Theory of Recollection," within the dialogue to answer this puzzle.
Plato's Theory of Recollection is the idea that human souls are immortal and already know all things before birth, so learning is nothing more than recalling (recollecting) knowledge gained in previous lives. Socrates conducted an experiment with an uneducated slave, asking only appropriate questions without teaching any geometry, leading the slave to arrive at the correct answer on his own (the slave dialogue). This famous scene is an episode demonstrating that the seeds of truth (latent knowledge) exist within people's souls and can be recollected through proper questioning. Indeed, through Socrates' series of questions, the slave arrives at the answer on his own, demonstrating that "unknown things" can be discovered. According to Plato, we exist in an intermediate state between complete ignorance and complete knowledge, and learning becomes possible by pursuing inquiry using partial knowledge (true beliefs) as clues. Thus Meno's Paradox ("Isn't learning impossible?") is resolved. Plato's Theory of Recollection is positioned as an example of innate ideas (knowledge inherently possessed) in later philosophy, and has been a subject of discussion from ancient times to the present as a theory indicating a source of knowledge independent of experience.
Michael Polanyi's Concept of "Tacit Knowledge"
The 20th-century philosopher of science Michael Polanyi explained the importance of "Tacit Knowledge" in works like The Tacit Dimension. According to Polanyi, there exists a portion of human knowledge that cannot be explicitly expressed in language or symbols. He stated, "Human beings know more than they can put into words," pointing out that much of knowing includes a tacit dimension that cannot be fully conveyed through text or diagrams. For example, riding a bicycle, playing a musical instrument, or the sense of facial recognition are knowledge difficult to fully verbalize in detailed procedures, knowledge that people acquire experientially and intuitively. Polanyi argued that such tacit knowledge is also contained in scientists' experimental skills and craftsmen's artistry, and that even scientific knowledge has personal elements that cannot be fully articulated. Indeed, he stated that "all knowledge is tacit knowledge or rooted in tacit knowledge. Completely explicit knowledge is unthinkable." In other words, even knowledge that we can explicitly verbalize (formal knowledge) is supported by unverbalized intuition and knack in its background, and tacit knowledge is the foundation of all knowledge.
In knowledge acquisition and transmission too, tacit knowledge holds great significance. Polanyi considered that acquiring tacit knowledge is insufficient through merely reading textbooks, and that learning through practice (experiential acquisition) is essential. In this respect, his thinking aligns with the maxim "practice makes perfect." For example, the knack of riding a bicycle is learned by actually riding and falling; verbal explanation alone won't instill it. Similarly, skilled craftsmen's techniques or researchers' intuition can only be transmitted through close master-apprentice relationships. Post-Polanyi researchers also point out that sharing tacit knowledge requires direct human communication and trust relationships, and mere information transfer is insufficient. Indeed, knowledge in specialized fields is often passed down through dialogue and collaborative work between masters (experts) and apprentices (trainees), where tacit knacks, aesthetics, and judgment are first conveyed. Thus Polanyi's concept of tacit knowledge revealed that knowledge is more than merely codified information, and is supported by embodied skills and experience. Knowledge acquisition requires not just memory and logic but practical training that draws out tacit elements, and knowledge transmission also requires shared experience beyond just documents and lectures.
Philosophical Thoughts with Similar Concerns (Western and Eastern)
The problem Plato raised—"How can we know unknown things?" "How is knowledge possible?"—appears in transformed forms in subsequent Western philosophy and Eastern thought. Below, using Aristotle, Kant, and Zen Buddhism as examples, we overview how each addressed problems of knowledge and enlightenment, and organize commonalities and differences.
Aristotle's Perspective: Knowledge Acquisition Through Experience and Intellect
Plato's student Aristotle addressed this problem from a position different from his teacher's Theory of Recollection. He denied innate ideas, considering the human mind as starting from a blank state (tabula rasa). That is, knowledge is not inherently possessed but gradually forms starting from sensory experience. Indeed, Aristotle stated that "our intellectual states (knowledge) are neither innate in predetermined form nor derived from higher knowledge, but develop based on sensory perception." This is a clear counter-concept to Plato's "the soul already learned everything in previous lives" Theory of Recollection, seeking the source of knowledge in this-worldly experience. However, Aristotle also recognized some internal capacity for knowledge formation. According to him, human reason (nous) has the capacity to accumulate individual cases from sensory experience and extract common essence (universal concepts). For example, by observing many swans, the universal judgment "swans are white" is formed—from repeated experience, intellect grasps general principles through induction. In this process, since the first principles (axioms) obtained finally by intellect cannot be deduced from other knowledge, Aristotle assumed intellectual intuition that ascends from directly perceived particulars to universals. In short, Aristotle thought humans acquire new knowledge through the interaction of sensory experience and intellectual intuition (understanding) that processes it to find meaning. This position answers the question "How can we know unknown things?" with "Humans have the capacity to gradually deepen understanding through experience." Unlike Plato's knowledge from previous lives, Aristotle showed a different approach where accumulation of experience in this life is the key to knowledge acquisition.
Kant's Perspective: A Priori Cognitive Framework and Experience
German philosopher Immanuel Kant also provided a unique answer to the problem "How do people acquire new knowledge?" Kant reconciled the conflict between rationalism (positions accepting innate ideas) and empiricism (positions that all knowledge is based on experience) prevalent until the 18th century, presenting an innovative viewpoint that integrated both. This is the so-called "Copernican Revolution": cognitive frameworks (categories and forms of intuition) are inherently possessed a priori in the human mind, and external objects appear in forms conforming to our cognitive framework. In Kant's own words, "A priori cognition through categories (concepts of understanding) is possible only when those categories derive from the nature of our mind and the mind imposes them on the objects we cognize." For example, forms like "space" and "time" are possessed by the mind prior to experience, and the miscellaneous impressions given by the senses are placed in the coordinates of space and time, then organized by 12 categories such as causality and substantiality, only then becoming empirical cognition. Thanks to such a priori cognitive frameworks, humans can obtain universal and necessary knowledge (like principles of mathematics and pure natural science) beyond mere aggregates of experience. Kant called this the possibility of "synthetic a priori judgments." That is, he explained how new insights independent of experience alone (truths universally valid beyond experience) are possible. His answer was that "our cognitive faculties themselves have a certain structure (form), and that structure itself gives order to experiential content, enabling new knowledge." This recognizes the existence of innate elements similar to Plato's Theory of Recollection, but differs in that these are not specific knowledge but conditions for making knowledge possible (cognitive frameworks). Also, while valuing experience like Aristotle, Kant's originality lies in ensuring universality and necessity that experience alone cannot explain through the structure of the human mind. For Kant, knowledge acquisition is a collaborative work of empirical elements from sensibility and a priori constituent elements from understanding. Through this position, he explained "mathematics and natural science work because our minds make the world read such structures," establishing a new epistemology incorporating the strengths of both empiricism and rationalism. However, Kant also stated that "things that cannot be captured by our cognitive framework (so-called thing-in-itself) are unknowable," pointing out the limits of cognition. In this respect, there are connections with Zen thought (mentioned later) regarding truth beyond language.
Zen Buddhism's Perspective: Enlightenment and Direct Transmission
Turning to Eastern thought, in Zen Buddhism we find similar concerns in its emphasis on "knowledge (enlightenment) that cannot be explained in words." The Zen tradition has mottos like "special transmission outside teachings" (kyōge betsuden) and "not establishing words and letters" (furitsu monji), holding that ultimate truth is transmitted not through scriptures or logic but through direct transmission of the dharma from master to disciple. This is the position that enlightenment (true wisdom) cannot be verbalized or conceptualized. Zen founders tried to have disciples intuitively experience enlightenment through methods like koans (paradoxical questions and answers) or meditation. For example, the first patriarch Bodhidharma taught "mind-to-mind transmission," and the story of the Flower Sermon—where Shakyamuni wordlessly held up a flower and Mahakashyapa smiled—is a famous symbol of non-verbal transmission of enlightenment. In Zen, enlightenment is considered awakening to Buddha-nature (one's nature as Buddha) that everyone inherently possesses. This means "enlightenment is not knowledge newly acquired from outside, but something that first blossoms by directly intuiting one's own nature"—an idea that can be seen as connected to Plato's Theory of Recollection. Indeed, Zen masters don't teach the content of enlightenment as doctrine to disciples. Rather, they use koans to stall disciples' logical thinking or lead them to realms beyond thought through daily work and zazen, promoting direct experience beyond language. The knowledge of enlightenment thus obtained is described as "ineffable" (fukasestu fukasestu) precisely because it cannot be explained. Zen thought developed a unique methodology of knowledge transmission: "transmitting from mind to mind through individual specific engagement, not relying on words or logic." This has connections to Polanyi's point about tacit knowledge transmission (emphasis on apprentice-style direct guidance). On the other hand, the enlightenment Zen aims for is a major transformation at the level of existence that transcends logical understanding, different in character from propositional knowledge discussed in Western philosophy. However, in that "the most important things cannot be taught with words," Zen provides unique insight into the wonder and limits of knowledge.
Comparison of Perspectives: Organizing Commonalities and Differences
The perspectives of Plato, Aristotle, Kant, Polanyi, and Zen Buddhism we've seen each have their own claims, but a common concern runs through them regarding the fundamental problems of "How can humans know unknown things?" and "How is knowledge acquired and transmitted?" At the same time, there are important differences in their answers. Below we organize the main commonalities and differences.
Focus on What Is Inherent: Plato and Zen Buddhism emphasize that truth (knowledge/enlightenment) originally exists within. Plato recognizes the seeds of knowledge in the immortal soul, Zen recognizes Buddha-nature within each person, viewing learning and practice as processes of drawing these out (recollection/awakening). In this sense, "learning" is understood as noticing what was latent rather than newly acquiring. Meanwhile, Aristotle and Polanyi also recognize that humans are equipped with innate cognitive abilities and physical skills (Aristotle's intellect, Polanyi's body knowledge). Kant also presupposes inherent elements in the form of cognitive frameworks. Thus many thinkers share a common recognition that "within humans exists some form of source of knowledge." However, what they see it as varies: memory of Ideas (Plato), categories of reason (Kant), intuitive understanding (Aristotle), embodied skills (Polanyi), Buddha-nature (Zen).
Emphasis on Experience and Practice: Aristotle and Polanyi particularly emphasize knowledge formation through experience and practice. For Aristotle, knowledge cannot be obtained without accumulation of sensory experience, and even theoretical cognition is based on induction from empirical facts. Polanyi also states that knowledge is supported by physical experience in the form of tacit knowledge, and that "doing is necessary for knowing." Zen also considers intuitive enlightenment as coming through accumulated practice of zazen and daily life, aligning on the point of practice over theory. Plato and Kant seem theory-oriented at first glance, but Plato also promotes recollection through the practice of dialogue and inquiry, and Kant also recognized that without empirical intuition (material given by sensibility), knowledge cannot be established. Therefore, the point that both experience and internal capabilities are necessary for knowledge acquisition is a common balance across many positions.
Verbalizability and Transmission: The limits of linguistic explanation are also a shared concern. Polanyi's tacit knowledge and Zen's enlightenment both have in mind "knowledge that cannot be fully explained in words." Plato is also said to have stated in his Seventh Letter that "philosophical truth cannot be conveyed in books," suggesting that methods beyond mere language are necessary for transmitting truth. On the other hand, Aristotle and Kant value clear explanation through logic and language, yet Aristotle held that first principles cannot be grasped without the intuition of experts (nous), and Kant stated that the categories of understanding themselves are a priori presuppositions inexplicable from experience. That is, elements that cannot be fully verbalized or theorized at the root of knowledge are tacitly acknowledged. Looking at knowledge transmission, Plato used dialogue and questioning methods, Kant valued "cultivating the power to think rather than just teaching" in his educational theory. Polanyi emphasized master-apprentice collaborative work, and Zen taught direct transmission beyond words and letters—all emphasizing deep communication beyond mere information transfer for passing on knowledge.
Approaches to the Unknown: Finally, let's summarize differences in answers to "How can we know unknown things?" Plato knows the unknown by recollecting "the already known" (memory of Ideas in the soul), Aristotle by generalizing unknown universals from experience. Kant explained that by using categories in the mind to constitute experience, new cognition (understanding of previously unknown things) becomes possible. Polanyi and Zen consider that unknown truth is grasped by experience and intuition rather than theory. These differ in approach, but share the point that "humans don't generate knowledge from complete nothingness but approach the unknown utilizing some clue (a priori elements, experience, intuition, etc.)." In other words, there's shared recognition that "we stand not in 'ignorance of ignorance' but 'between the known and unknown.'" Plato saw this as the soul's preliminary knowledge, Aristotle as sensory perception and intellectual workings, Kant as the structure of cognitive faculties, Zen as Buddha-nature and the master's guidance. Though expressions differ, there's great ideological continuity in the optimism that "humans have latent power to know the unknown" and the insight that "appropriate methods are needed to draw out that power."
In summary, from Plato's Meno's Paradox through Polanyi's tacit knowledge to Aristotle, Kant, and Zen Buddhism, the thoughts that have faced the paradox of knowledge are diverse, but common themes can be found even among seemingly scattered discussions. That is the question "How can humans know (and how skillfully) and transmit things to others?" Some called it recollection, others called it empirical knowledge or intuition, and still others called it categories, tacit knowledge, or enlightenment. The philosophical answers differ by era and context, but by comparing them, wisdom about the establishment and transmission of knowledge emerges from multiple angles. This theme continues to be discussed because continuing to ask what knowledge is itself is the driving force of our intellectual inquiry.