The idea that science has an essential and ineliminable tacit element was first popularised in the twentieth century by the chemist turned philosopher Michael Polanyi. He begins his book length treatment of tacit knowledge in The Tacit Dimension by saying:
I shall reconsider human knowledge by starting from the fact that we can know more than we can tell. This fact seems obvious enough; but it is not easy to say exactly what it means. Take an example. We know a person’s face, and can recognize it among a thousand, indeed among a million. Yet we usually cannot tell how we recognize a face we know. So most of this knowledge cannot be put into words. [Polanyi 2009: 4]
The suggestion is that tacit knowledge is tacit because it is ‘more than we can tell’. We cannot tell how we know things that we know tacitly. But what argument does he give for this? What are the limits on what can be said still leaving something that can be known?
In Personal Knowledge, Polanyi’s strategy is to examine how what can be said or, more broadly, articulated both leaves room for and depends on something outside what can be articulated. There are two key arguments. One depends on the kind of representation available to summarise explicit knowledge in science. The other depends more broadly on recognition from which follow more general claims about representation. I will suggest that the latter is the fundamental argument but start with the former.
Taking the example of knowledge of the spatial configuration of organs in the body, Polanyi argues this cannot be captured in a representation.
The major difficulty in the understanding, and hence in the teaching of anatomy, arises in respect to the intricate three-dimensional network of organs closely packed inside the body, of which no diagram can give an adequate representation. Even dissection, which lays bare a region and its organs by removing the parts overlaying it, does not demonstrate more than one aspect of that region. It is left to the imagination to reconstruct from such experience the three-dimensional picture of the exposed area as it existed in the unopened body, and to explore mentally its connections with adjoining unexposed areas around it and below it.
The kind of topographic knowledge which an experienced surgeon possess of the regions on which he operates is therefore ineffable knowledge. [Polanyi 1974: 89]
Three-dimensional spatial knowledge is ineffable or tacit because it cannot be captured in a representation. Polanyi argues that even if all human bodies were identical and even if there were a map comprising cross sections based on ‘a thousand thin slices’ of the body, that in itself would not articulate the knowledge of a trained surgeon. Someone knowing merely the former ‘would know a set of data which fully determine the spatial arrangement of the organs in the body; yet he would not know that spatial arrangement itself’ [89]. An additional act of interpretation is needed. But because that act cannot itself be encoded in a representation, according to Polanyi, it remains tacit.
The argument is a little surprising. Polanyi concedes that that the set of cross sectional representations, presumably alongside some further information about their inter-relations, such as their order and distance apart, ‘fully determine[s] the spatial arrangement of the organs’ and yet denies that this amounts to an articulation of the three-dimensional understanding. Without the further information this certainly would not be an articulation of the skilled surgeon’s knowledge. But then neither would it fully determine the arrangement. With that addition, however, why would this not count as explicit knowledge?
A further clue runs thus:
The difficulty lies here entirely in the subsequent integration of the particulars and the inadequacy of articulation consists altogether in the fact that the latter process is left without formal guidance. The degree of intelligence required from the student to perform the act of insight which ultimately conveys to him the knowledge of the topography, offers here a measure of the limitations of the articulation representing this topography. [ibid: 90]
Again there is something confusing here. If the integration of partial representations such as the set of cross sections really is left without formal guidance then, again, it is clear why they cannot articulate the full knowledge. But neither would they determine the arrangement.
The difficulty with interpreting this argument is that of balancing the claim that spatial configuration is both determined but also ineffable.
I think that the clue to its interpretation is to realise that whether a symbol logically determines anything always, according to Polanyi, depends on a tacit element. This is supported by the first argument.
I may ride a bicycle and say nothing, or pick out my macintosh among twenty others and say nothing. Though I cannot say clearly how I ride a bicycle nor how I recognise my macintosh (for I don’t know it clearly), yet this will not prevent me from saying that I know how to ride a bicycle and how to recognise my macintosh. For I know that I know how to do such things, though I know the particulars of what I know only in an instrumental manner and am focally quite ignorant of them. [ibid: 88]
Polanyi suggests that the recognitional skill involved in the second example is akin to the practical skill of the first. In both cases, the knowledge-how depends on something which is not explicit: the details of the act of bike riding or raincoat recognition. But if that is the case then recognising instances of the same linguistic or conceptual type looks also to be a case of a recognitional skill in which the particular clues to the recognition are unknown.
[I]n all applications of a formalism to experience there is an indeterminacy involved, which must be resolved by the observer on the ground of unspecified criteria. Now we may say further that the process of applying language to things is also necessarily unformalized: that it is inarticulate. Denotation, then, is an art, and whatever we say about things assumes our endorsement of our own skill in practising this art. [ibid: 81]
This connection between denotation and tacit recognitional skills appears to be the fundamental argument for the importance of tacit knowledge for explicit scientific accounts. Polanyi summarises the connection thus:
If, as it would seem, the meaning of all our utterances is determined to an important extent by a skilful act of our own – the act of knowing – then the acceptance of any of our own utterances as true involves our approval of our own skill. To affirm anything implies, then, to this extent an appraisal of our own art of knowing, and the establishment of truth becomes decisively dependent on a set of personal criteria of our own which cannot be formally defined.... [E]very where it is the inarticulate which has the last word, unspoken and yet decisive... [ibid: 70-71]
But if this is the key argument, everything depends on the strength of the claim that recognition requires a tacit element.
