Wednesday, 3 August 2011

Tacit knowledge and practical and recognitional clinical skills

A work in progress chapter for a clinical book.

Tacit knowledge and practical and recognitional clinical skills

Whilst the emphasis in thinking of the content of natural sciences is generally on impersonal explicit knowledge, there is also an important ‘tacit’ element. This is especially true of sciences, or science-based disciplines, which contain a practical aspect. Surgery is a clear example of this. Nevertheless, exactly what tacit knowledge comprises is still a matter of debate. How can something count as knowledge but remain tacit? Clues include its connection to know-how or ability, the fact in some sense it cannot be put into words but that it depends on practical contexts.

This chapter will start by looking to a pair of arguments for tacit knowledge by the chemist turned philosopher of science Michael Polanyi who first drew attention to in the middle of the C20 in two books: Personal Knowledge and The Tacit Dimension.

But first, what does Polanyi mean by ‘tacit’ knowledge? A clear statement runs thus:

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 1967: 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 of relevance to this chapter. One depends on limits on the kind of representation available to summarise explicit knowledge in science, thus indicating a need for tacit knowledge. The other depends on an analysis of what is involved in recognition (an argument which promises to impact on diagnostic judgement), which also connects to Polanyi’s views of how linguistic representation in general is possible. I will suggest that this latter argument is the fundamental argument but start with the former.

To examine the limits of scientific representation, Polanyi considers the understanding that a skilled surgeon has of the spatial configuration and orientation of organs in the body. He argues that 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 1962: 89]

The claim here is that three-dimensional spatial knowledge is ineffable, or tacit, because it cannot be captured in a representation. Polanyi goes on to argue 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 or imagination is needed. But because that act cannot itself be encoded in a representation, according to Polanyi, it remains tacit.

This argument is a little surprising. Polanyi concedes 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 about the relations between the set of maps, the maps alone would not be an articulation of the skilled surgeon’s knowledge. But then neither would they fully determine the arrangement of bodily organs. With that addition, however, why would this not count as an articulation of their knowledge and thus imply that it could be explicit knowledge?

A further possible clue to Polanyi’s thinking 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]

But there remains something strange about this line of thought. If the integration of the partial representations, such as the set of cross sections, were left without formal guidance then it would be clear why the partial representations could not articulate the surgeon’s knowledge. But neither would they determine the arrangement of organs as Polanyi has previously asserted.

The difficulty with interpreting this argument is that of balancing the claim that spatial configuration is both determined by what can be represented but remains ineffable and thus tacit rather than explicit.

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 a different 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 skill involved in the example of recognising a macintosh is akin to the practical skill of cycle riding. In both cases, the ‘knowledge-how’ depends on something which is not explicit: the details of the act of bike riding or raincoat recognition. Whilst one can recognise one’s own macintosh, in the example, one is ignorant of how. Thus how one does this is tacit.

If this argument is successful it is of general significance because it would carry over to the recognitional skill which underpins all medical classification such as diagnosis but also all linguistic labelling generally. Indeed, Polanyi makes this connection explicilty.

[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]

Although this connection looks to be of fundamental importance in linking the tacit dimension between recognising particulars and the use of language in general, Polanyi seems to overstate his case in a way which has significance for understanding tacit knowledge. He says of bicycle riding and macintosh recognition that we know how to do them despite being ‘focally quite ignorant of’ the particulars by which we know how to do them. That thought seems to justify his slogan that we know more than we can tell. But whilst that is a dramatic claim, it does suggest a dilemma for tacit knowledge.

How can tacit knowledge be both tacit and still knowledge? To count as knowledge, there must be something, some content, to be known. But if it cannot be said or told, what sense is there to the idea that there is anything known? If, on the other hand, the content can be articulated, in what sense is it tacit? The paradigmatic way to articulate knowledge is in language and that seems to mark the knowledge out as explicit.

I suggest that the best solution to that dilemma starts by contesting both Polanyi’s slogan and his account of recognition. Polanyi says that one is ignorant of how one recognises one’s own macintosh. But that is a surprising claim. It would be very surprising – and undermine the veracity of the claim – if one could say nothing about how one recognises something as one’s own coat. It is surely more plausible that one might say: “I recognise that it is my macintosh because of how it looks here! with the interplay of sleeve, shoulder and colour.” Or, “there is something about the shape of the lapel here! that is distinct.” One might be able to say this even if one could not recognise a separated sleeve, shoulder or paint colour sample as of the same type or describe the lapel when it is unseen or give a precise name to the colour.

There are some recognitional judgements that do not depend on subsidiary elements (as recognising a macintosh by its sleeves or lapels). One might recognise a colour as the same as another in a variety of ways. One might judge the colour of a sample to be the same colour as a previously encountered one or as the very same (indistinguishable) shade as another adjacent sample. In such cases, the judgement of sameness of colour or sameness of shade might not be made in virtue of anything else (such as a label) but rather a direct judgement of sameness of colour or shade. Still, that is not to say that we know more than we can tell. We can express what we know by pointing to the samples and saying that they are the same colour or shade. In so doing, we express what we know.

The same goes for practical knowledge-how. If one knows how, and is able, to ride a bicycle then one knows that the pedalling should be like this! and the brakes applied progressively like this! It is not that one is ignorant of how to ride even if one does not pay attention to it. If one does not pay attention to how one is riding that does not mean that one cannot put one’s ability into situation-dependent words, but rather that one does not. (That one cannot without paying attention is trivial.)

The connection between practical knowledge and tacit knowledge on this account suggests the need for practical teaching to convey the relevant knowledge. Such tacit knowledge inherits the well known feature of bodily skills that learning them in general requires practice. The same is true for recognitional skills even though they do not require bodily dexterity. Here is one reason for that.

I have discussed recognising a particular macintosh as one’s own and also of recognising a colour. But there are differences. The former is literally a matter of re-cognising the very same entity. But recognising that something has the same colour as something else is not a matter re-cognising the same entity [Travis 2006: 189-93]. Colours are not entities but properties (whatever exactly the preferred scientific account of colour). To recognise something as having the same colour as something else is to judge it to be relevantly similar with respect to colour. In some contexts that might be judging that the same broad colour word applies to it, for example, ‘red’. In others, it might turn on being of indistinguishable shade to the human eye in standard lighting conditions. In clinical cases it might be within limits fixed by medical significance (is the blood sufficiently oxygenated?). To learn to ‘recognise’ or judge colour in such circumstances is an open ended skill requiring practice like other skills.

That however is the general nature of medical classification. It turns on applying diagnostic labels because of relevant similarities between individual cases and hence on context-dependent recognitional judgements. There is thus some continuity between bodily skills, such as the ability to perform a particular surgical technique, and recognitional skills.

Context-dependent recognitional judgements are a way of putting what one knows into words. But, unlike paradigmatic explicit knowledge they are not context-independent or general claims. Rather, they depend on the presence of what is judged. They are tacit or silent insofar as they cannot be put into words outside particular environments or contexts. Thus they contrast with the general and context-independent claims of much of science. Polanyi’s achievement was to draw attention to their importance, nevertheless, for science.

Polanyi, M. (1962) Personal Knowledge, Chicago: University of Chicago Press
Polanyi, M. (1967) The Tacit Dimension, Chicago: University of Chicago Press
Travis, C. (2006) Thought’s Footing, Oxford: Oxford University Press