The Tacit Dimension
Source: https://archive.org/details/tacitdimension0000pola ↗
Full text: Internet Archive ↗
"We can know more than we can tell." Polanyi's slogan is the quiet demolition of the entire "ask the corpus" shortcut.
He shows that most functional human knowledge is tacit — we recognize a face, ride a bicycle, or judge that a design is off without being able to state how — and that this inarticulate knowing does the real work in every skilled practice, resting beneath the thin visible layer of what we can put into words.
The consequence is decisive for research: a corpus, and any model trained on one, contains only what has been made explicit, while the knowledge that governs how work is actually done was never written down and so is absent from the data by definition.
This is why observation beats interviews, interviews beat surveys, and all of them beat asking a machine — each step toward the situation recovers more of the tacit dimension no text holds.
Users cannot tell you most of what they know; fieldwork exists precisely to reach the part that was never said.
The indispensable statement of what secondary sources structurally cannot contain.
Central argument
Polanyi argues that human knowing is rooted in a tacit dimension — 'we can know more than we can tell' — in which we attend from a set of particulars we cannot fully specify toward a coherent whole we can recognize and act on. Skilled performance, perception, and discovery all rely on this inarticulate integration of clues; explicit, statable knowledge is the visible tip resting on a much larger submerged mass. He develops the structure of tacit knowing (the from-to relation between subsidiary and focal awareness) and argues it is indispensable even to science, which cannot be reduced to explicit method.
Critique
Polanyi's account is more phenomenological description than testable theory, and 'tacit knowledge' has since been stretched to cover almost anything hard to write down, diluting its force. Later scholars (notably Harry Collins) argue he conflates several distinct kinds of tacitness, some of which can in fact be made explicit or automated. The book is also compact to the point of ellipsis, assuming the reader will supply connective tissue. But the central insight — that articulable knowledge rests on a larger inarticulable base — is robust and consequential.
Why it matters for product
This book is the epistemological core of why fieldwork cannot be replaced by querying a corpus: a corpus holds only what was made explicit, while the knowledge that actually governs skilled practice is largely tacit and was never written down. For product leaders it explains why users can't simply tell you what they need, why watching beats asking, and why a model — trained exclusively on the explicit record — is structurally blind to the tacit dimension that discovery exists to reach. 'We can know more than we can tell' is the one sentence that dismantles the synthetic-research shortcut.