Polanyi thus drew attention to the all-important, not-yet-cognitive awareness that makes thematic knowledge possible. This tacit dimension is the nonarticulated element in perception and knowledge, an unreflective awareness of things that is quite different from the clear-cut awareness we have when we perform the mental act of focusing our attention directly and thematically on an object. Polanyi's most famous catchphrase was the expression, "We always know more than we can tell."

These Polanyian insights into the nature of knowledge have some helpful implications for theology in general but for Trinitarian theology in particular. Scottish theologian Thomas F. Torrance offers the following compressed account of tacit knowledge:

It is on this deep subsidiary awareness that all skills, explicit thought, formal reasoning, and articulate knowing and communication rely. Even the most completely formalized knowledge (e.g. through logic or mathematics) must include informal or tacit coefficients, for it is only by relying on them that formal systems can operate meaningfully. This is evident in the bearing of thought and speech upon some reality of the bearing of some skill upon an intended end; and also in the way our minds spontaneously integrate particulars into significant wholes, as in the recognition of a physiognomy, or integrates clues into a focal target, as in scientific intuition and discovery. Tacit knowing, Polanyi claims, is the fundamental power of the mind which creates explicit knowing and lends meaning to and controls its use. Tacit knowledge and explicit knowledge are opposed to one another but they are not sharply divided. While tacit knowledge can be possessed by itself, explicit knowledge must rely on being tacitly understood and applied. Hence all knowledge is either tacit or rooted in tacit knowledge. A wholly explicit knowledge is unthinkable. This tacit dimension provides the unifying ground of all knowledge, rooting it in the concrete situations of life and society in the world; and as such provides the continuous epistemological field which integrates the sciences and the arts and does away with age-old dualisms which have led to the fragmentation of human culture.                   

Explicit knowledge, then, depends on a prior unity richer and fuller than the propositions gathered around it. This tacit coefficient of all explicit knowledge is especially important for coming to conscious and disciplined understanding of very large, subtle, or complex subjects that bear within themselves implications for a broad range of subsidiary fields. This brings us back, at last, to Trinitarianism.

The tacit dimension of knowledge is especially relevant in Trinitarian theology. It is what enables the theology teacher to utter that all-important phrase "You know" and expect realistically to make connections with the audience. The Christian teacher taking up the subject of the Trinity should be able to invoke some range of experience or of implicit understanding and familiarity that can then be explicated in propositional teaching on the subject: 

"You know, the Trinity, like we sing about in the church";

"You know, the Trinity, like is all over the Bible";

or "You know, the Trinity, like every Christian believes in."   

Without this tacit awareness of the Trinity, explicit teaching on the subject will always seem like a foreign body rudely interjected into an otherwise reasonable nexus of beliefs. This is because the doctrine of the Trinity is so large, fundamental, and all-encompassing. Scottish theologian Thomas F. Torrance, whose summary of Polanyi's categories we just quoted at length, has done more than any other theologian to use Polanyian insights for theology in general and for the Trinity in particular. Here is his masterly account of how vigorous Trinitarianism relies on the tacit dimension: