Not all knowledge can be written down. This distinction, foundational in knowledge management theory, has profound implications for what PKM systems can and cannot do.
Polanyi's Insight
Michael Polanyi articulated the core problem in 1966: "We know more than we can tell." You can ride a bicycle but you can't fully explain how. You can recognize a face but you can't describe the algorithm. You can sense when a codebase is poorly designed but you can't always articulate the rules being violated. This is tacit knowledge: embodied, experiential, resistant to codification.
Explicit knowledge, by contrast, is knowledge that has been articulated, codified, and made transferable. A recipe, a formula, a documented process. It can be written down, stored, searched, and shared.
The SECI Model
Ikujiro Nonaka and Hirotaka Takeuchi (1995) proposed the SECI model describing four modes of knowledge conversion:
- Socialization (tacit → tacit): Learning through shared experience. Apprenticeship, pair programming, watching someone work. Knowledge transfers without ever being made explicit.
- Externalization (tacit → explicit): Articulating tacit knowledge into words, models, or frameworks. This is the hardest and most valuable conversion. Writing about your intuitions, creating mental models, explaining your decision-making process.
- Combination (explicit → explicit): Merging, categorizing, and restructuring existing explicit knowledge. Most traditional PKM operates here: organizing notes, creating syntheses, building MOCs.
- Internalization (explicit → tacit): Learning by doing. Reading a technique and then practicing it until it becomes second nature. The knowledge disappears back into embodied skill.
Implications for PKM
Most PKM systems deal almost exclusively with explicit knowledge. Notes, highlights, documents, links. This is a genuine limitation. The most valuable knowledge a person possesses (professional intuition, taste, judgment, relational understanding) often resists capture.
This doesn't make PKM useless; it means PKM practitioners should be honest about what their systems can and cannot hold. Strategies for engaging with tacit knowledge include: reflective journaling (attempting externalization), documenting decision rationales (capturing the reasoning behind intuitive choices), maintaining practice logs, and deliberately seeking apprenticeship-style learning for skills that resist textual capture.
The Organizational Dimension
Nonaka and Takeuchi's work was originally about organizational knowledge creation, not personal systems. But the SECI model applies at the individual level too. Your personal knowledge spiral involves all four modes: you learn from others (socialization), write down what you've learned (externalization), organize and connect it (combination), and practice until it becomes intuitive (internalization).
Key Points
- Tacit knowledge (embodied, experiential) resists capture; explicit knowledge (codified, articulable) is what PKM systems primarily handle
- Polanyi's "we know more than we can tell" sets a fundamental boundary on knowledge management
- The SECI model describes four conversion modes: Socialization, Externalization, Combination, Internalization
- Externalization (tacit → explicit) is the most difficult and valuable conversion for PKM practitioners
- Reflective journaling and decision documentation are practical strategies for engaging with tacit knowledge
Open Questions
- Can AI tools help externalize tacit knowledge by asking probing questions that surface implicit assumptions?
- How should PKM systems acknowledge the limits of what they contain?
- Is the rise of video and audio capture narrowing the tacit-explicit gap?
References
- Polanyi, M. (1966). "The Tacit Dimension"
- Nonaka, I., & Takeuchi, H. (1995). "The Knowledge-Creating Company"