This is a substantial reworking of a previous draft chapter for the Oxford Handbook of Philosophy and Psychiatry.
Abstract
This chapter contrasts
the recent emphasis on operationalism as the route to reliability in psychiatry
with arguments for an ineliminable role for tacit knowledge. Although Michael
Polanyi is widely credited with the most forceful arguments for the presence of
a tacit dimension, I argue that two clues he offers as to its nature – that we
know more than we can tell and that knowledge is an active comprehension of
things known – are better interpreted through regress arguments set out both by
Ryle and Wittgenstein. Those arguments, however, suggest that tacit knowledge
is not inexpressible but merely inexpressible in context-free terms. Tacit
knowledge is context-dependent practical knowledge. So understood, the regress
arguments suggest that the operational approach to psychiatric diagnosis can
never free itself from a tacit dimension. Given that claim then Parnas’
opposing view of diagnosis can be seen as a way to embrace, rather than deny,
the importance of tacit knowledge and skilled clinical judgement for
psychiatry.
Introduction
In this chapter, I will
examine the role of clinical judgement in the recognition of psychiatric
symptoms via the idea that this involves an ineliminable tacit dimension. I
will do this by examining three authors (Polanyi, Ryle and Wittgenstein) who
offer support for the existence of some form of tacit knowledge. But I will
place them in the context, in this section, of the dominant criteriological
approach to psychiatric diagnosis and, in the final section, one reaction against
it.
One reason for
doubting, or playing down, a role for tacit knowledge in psychiatric diagnosis
is the influence of operationalism in a quest for reliability for the last 50
years or so. There were two main factors which explain this.
Firstly, on its
foundation in 1945, the World Health Organisation set about establishing an
International Classification of Diseases (ICD). Whilst the chapters of the
classification dealing with physical illnesses were well received, the
psychiatric section was not widely adopted and so the British psychiatrist
Erwin Stengel was asked to propose a basis for a more acceptable
classification. Stengel chaired a session at an American Psychological
Association conference of 1959 at which the philosopher Carl Hempel spoke. As a
result of Hempel’s paper (and an intervention by the UK psychiatrist Sir Aubrey
Lewis) Stengel proposed that attempts at a classification based on theories of
the causes of mental disorder should be given up (because such theories were
premature), and suggested that it should instead rely on what could be directly
observed, that is, symptoms.
In fact, Hempel’s paper
provided only partial support for the
moral that was actually drawn for psychiatry. He argued that:
Broadly speaking, the
vocabulary of science has two basic functions: first, to permit an adequate
description of the things and events that are the objects of scientific
investigation; second, to permit the establishment of general laws or theories
by means of which particular events may be explained and predicted and thus
scientifically understood; for to understand a phenomenon scientifically is to
show that it occurs in accordance with general laws or theoretical principles.
[Hempel 1994: 317]
These two requirements
– that terms employed in classifications should have clear, public criteria of
application and should lend themselves to the formulation of general laws –
correspond to the aims of reliability
and validity respectively. But it was
the former that was adopted by psychiatry as the key aim at the time. With
respect to it, Hempel claims that
Science aims at
knowledge that is objective in the
sense of being intersubjectively certifiable, independently of individual
opinion or preference, on the basis of data obtainable by suitable experiments
or observations. This requires that the terms used in formulating scientific
statements have clearly specified meanings and be understood in the same sense
by all those who use them. [ibid: 318]
He commends the use of
operational definitions (following Bridgman’s book The Logic of Modern Physics [Bridgman 1927]), although he
emphasises that in psychiatry the kind of measurement operations in terms of
which concepts would be defined would have to be construed loosely. This view
has been influential up to the present WHO psychiatric taxonomy in ICD-10.
The second reason for
the emphasis on reliability and hence operationalism was a parallel influence
from within American psychiatry that shaped the writing of DSM-III. Whilst
DSM-I and DSM-II had drawn heavily on psychoanalytic theoretical terms, the
committee charged with drawing up DSM-III drew on the work of a group of
psychiatrists from Washington University of St Louis. Responding in part to
research that had revealed significant differences in diagnostic practices
between different psychiatrists, the ‘St Louis group’, led by John Feighner,
published operationalised criteria for psychiatric diagnosis. The DSM-III task
force replaced reference to Freudian aetiological theory with more
observational criteria. The task force leader, Robert Spitzer, later reported: ‘With
its intellectual roots in St. Louis instead of Vienna, and with its
intellectual inspiration drawn from Kraepelin, not Freud, the task force was
viewed from the outset as unsympathetic to the interests of those whose theory
and practice derived from the psychoanalytic tradition.’ [Bayer and Spitzer
1985: 188 quoted in Shorter 1997: 301-2].
This stress on
operationalism has had an effect on the way that criteriological diagnosis is
codified in DSM and ICD manuals. Syndromes are described and characterised in
terms of disjunctions and conjunctions of symptoms. The symptoms are described
in ways influenced by operationalism and with as little aetiological theory as
possible. (That they are neither strictly operationally defined nor strictly
aetiologically theory free is not relevant here.) Thus one can think of such a
manual as providing guidance for, or a justification of, a diagnosis offered by
saying that a subject is suffering from a specific syndrome. Presented with an
individual, the diagnosis of a specific syndrome is said to be justified
because he or she has enough of the relevant symptoms which can be, as closely
as possible, ‘read off’ from their presentation. Such an approach to psychiatric
diagnosis plays down the role of individual judgement or tacit knowledge
amongst clinicians.
Polanyi on tacit knowledge
Whilst the influence of
operationalism deployed in the service of reliability aims to remove or reduce
the presence of judgement and thus an uncodified tacit element in psychiatric
diagnosis, there is a tradition in the history and philosophy of science
(dating from about the same time) which stresses an ineliminable role for tacit
knowledge in science. In this section, I will examine arguments offered by the
chemist turned philosopher of science Michael Polanyi.
But first, what does
Polanyi mean by ‘tacit’ knowing or knowledge? (Polanyi himself talks of tacit knowing rather than knowledge. I will,
nevertheless, use ‘knowledge’ whilst talking about his views but will return to
emphasise the practical dimension to what is tacit.) In this chapter, I will
follow two clues. The first comes from the start of his book The Tacit Dimension.
I shall reconsider
human knowledge by starting from the fact that we can know more than we can tell. [Polanyi 1967b: 4]
The second clue comes
from his book Personal Knowledge in
which he says:
I regard knowing as an
active comprehension of things known, an action that requires skill. [Polanyi
1958: vii]
These passages suggest
two features tacit knowledge might have: that it is not, or perhaps cannot be
made, explicit and that it is connecte to action: the personal practical
knowledge of a skilled agent. I will start with the first clue and, in later
sections, return to the second. The first clue (that we can know more than we
can tell) continues:
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 1967b: 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 space 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 possesses 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 represent the arrangement of bodily organs. With the addition
of that further information, however, why would this not count as an
articulation of the surgeon’s knowledge? If so it would be explicit, rather
than merely tacit, 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, in some sense, of how. Thus how one does this is
tacit.
If this argument were
successful it would be of general significance because it would also apply to
the recognitional skill which underpins classification such as diagnosis in
psychiatry but also lingusitic labelling generally. Indeed, Polanyi makes this
connection explicitly.
[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]verywhere
it is the inarticulate which has the last word, unspoken and yet decisive...
[ibid: 70-71]
Note that the argument
for the claim about the art of denotation being tacit seems to rest on an
appeal to the apparently clearer case of the recognition of particulars – such
as a particular macintosh – which, he argues, depends on features of which one
is focally ignorant. There is a difference between the two cases. The example
he gives concerns a particular macintosh as one’s own among a pile of them. It
is not the judgement that the object is a macintosh, but the recognition
(re-cognition) of that particular
macintosh. But I will ignore that difference in what follows.
To justify his claim
about denotation he needs to defend the general claim that explicit recognition
of something as an instance of a type, such as ‘macintosh’, is based on the
implicit recognition of subsidiary properties of which one is focally ignorant.
In other words, to recognise a feature (F, say) one must a) always recognise it
in virtue of something else (subsidiary features G, H and I, eg.) of which b)
one is focally ignorant. But it is not clear that either part of this claim is
true.
To consider the claim,
it will help to make clearer what Polanyi means by focal attention and
subsidiary awareness. Elsewhere he uses the sample of pointing to something
using a finger.
There is a fundamental
difference between the way we attend to the pointing finger and its object. We
attend to the finger by following its
direction in order to look at the object. The object is then at the focus of our attention, whereas the finger is not seen focally, but as a pointer to the object. This
directive, or vectorial way of attending to the pointing finger, I shall call
our subsidiary awareness of the finger.
[Polanyi 1967a: 301]
In attending from the
finger to the object, the object is the focus of attention whilst the finger,
though seen, is not attended to. Note, however, that the finger is not
invisible. It could itself be the object of focal attention were it attended
to. This suggests that the first part of the general claim that Polanyi needs
itself faces an objection based on a regress. The recognition of an instance of
a type or kind depends on subsidiary awareness of something else which could
have been the object of focal awareness and thus would have depended on
subsidiary awareness of something else.
This is a potential
rather than a vicious regress. (It is not that in order to have subsidiary
awareness of something one must already or actually have had focal awareness of
it or anything else. Combined with Polanyi’s general claim, that thought would
have generated a vicious regress.) Nevertheless, even the potential regress
suggests something implausible about Polanyi’s general claim. It does not seem
reasonable to think that it is always the case that recognition of the instantiation
of a kind depends on subsidiary awareness of something else. Take the case of
the recognition that something is an instance of redness. Surely the
recognition that x is red turns on a matter of focal awareness of its colour,
not subsidiary awareness of anything else?
Polanyi seems to assume
that the question of how one recognises something to be of an instance of a
particular kind always has an informative answer (and to cover cases where it
is not obvious what this is, the second move he makes is to assume that it is
tacit). But whilst it sometimes may have an informative answer, there is no
reason to think that it always has. In the next section I will return to this
point. This line of thought puts the first part of Polanyi’s claim – that to
recognise a feature (F, say) one must a) always recognise it in virtue of
something else (subsidiary features G, H and I, eg.) – under pressure. What of
the second aspect: that one must be focally ignorant of the subsidiary
features?
Even in cases where one
recognises a particular as an F in virtue of its subsidiary properties G, H, I,
and cannot give an independent account of
those properties, it is not clear that one need be focally ignorant of
them. It may be, instead, that the awareness one has of G, H, I is manifested
in the recognition of something as an F or a particular F. One might say, I
recognise that this is a macintosh (or even my macintosh) because of how it
looks here with the interplay of
sleeve, shoulder and colour even if one could not recognise a separated sleeve,
shoulder or paint colour sample as of the same type. Whilst it seems plausible
that one might not be able to say in context-independent terms just what it is
about the sleeve that distinguishes a macintosh from any other kind of raincoat
(one may, for example, lack the vocabulary of fashion or tailoring) that need
not imply that one is focally ignorant of, or not attending to, just those
features that make a difference. Recognition may depend on context-dependent or
demonstrative elements, such as recognising shapes or colours for which one has
no prior name. But if anything, that suggests one has to be focally aware, not
focally ignorant, of them.
In summary, two claims
seem to support Polanyi’s case. First, one is sometimes focally unaware of
features that underpin one’s recognitional abilities. Second, one cannot always
say in general term on what features one’s recognition depends. But these do
not support the general claim that (focal) recognition of one feature always
depends on merely subsidiary awareness of something else. And if not, then
Polanyi has not offered a general reason to hold that recognition is a tacit skill.
The tacit element in recognition
I argued in the
previous section that Polanyi’s argument for the role of a tacit element in
science turns on an argument that it is fundamental in recognition, including
the recognition which underpins the ‘art of denotation’. Polanyi suggests that
tacit knowledge is that which falls outside linguistic articulation or
representation. But such representation presupposes
recognitional know-how rather than the other way round. So the know-how that
constitutes recognition is not itself articulated but rather tacit.
I argued, however, that
Polanyi’s argument for the role of tacit knowledge in recognition is not
successful because he has to assume that to recognise a feature (F, say) one
must a) always recognise it in virtue of something else (subsidiary features G,
H and I, eg.) of which b) one is focally ignorant. But neither point – a) and
b) – is compelling. There are, however, two other arguments which were both
framed at about the same time as Polanyi’s and which seem to suggest limits
both to what can be put into words (which resistance Polanyi takes to indicate
tacit-status) and the importance of a practical dimension underlying linguistic
competence, picking up Polanyi’s second clue. These are Gilbert Ryle’s argument
that knowledge-how is a concept logically prior to the concept of
knowledge-that and Ludwig Wittgenstein’s regress argument concerning
understanding a rule. I will now explore the extent to which these support
Polanyi’s emphasis on a tacit dimension.
Ryle’s argument takes
the form of a regress.
If a deed, to be
intelligent, has to be guided by the consideration of a regulative proposition,
the gap between that consideration and the practical application of the
regulation has to be bridged by some go-between process which cannot by the
pre-supposed definition itself be an exercise of intelligence and cannot, by
definition, be the resultant deed. This go-between application- process has
somehow to marry observance of a contemplated maxim with the enforcement of
behaviour. So it has to unite in itself the allegedly incompatible properties
of being kith to theory and kin to practice, else it could not be the applying
of the one in the other. For, unlike theory, it must be able to influence
action, and, unlike impulses, it must be amenable to regulative propositions.
Consistency requires, therefore, that this schizophrenic broker must again be
subdivided into one bit which contemplates but does not execute, one which
executes but does not contemplate and a third which reconciles these
irreconcilables. And so on for ever. [Ryle 1945: 2]
There has been a recent
flurry of literature on the precise nature of this argument and thus whether it
is successful [eg Stanley and Williamson 2001; Noë 2005; for detailed
assessment see Gascoigne and Thornton forthcoming]. But it seems to involve
something like the following regress:
Suppose all know-how
can be articulated (put into words) as a piece of knowledge-that: grasping some
proposition that p. Grasping the proposition that p is itself something one can
do successfully or unsuccessfully, so it is also a piece of know-how. So, on
the theory in question, it will involve grasping another proposition, call this
q. But grasping the proposition that q is itself something one can do
successfully or unsuccessfully, so it is also a piece of know-how. So, on the
theory in question, it will involve grasping another proposition, call this
r.... etc
If the first step of
the reductio is designed to ‘articulate’ or represent a piece of otherwise
merely tacit knowledge at the heart of recognition, it will lead to a regress.
Ryle himself suggests that it can be used to undermine what he calls an ‘intellectualist
legend’ which attempts to explain practical knowing-how though a deeper,
theoretical form of knowing-that based on grasping a proposition. His counter
argument is that, since grasping a proposition can be done well or badly, the
only way to avoid the vicious regress is to grant that intelligence can accrue
to, and be manifested in, practical knowledge directly, without further
theoretical explanation or underpinning. Knowing-how is more basic than knowing-that.
What is the
relationship between Ryle’s argument and Polanyi’s views of tacit knowledge? On
the one hand, it offers some nuanced support. Polanyi’s claim that we know more
than we can tell as is one of his two main clues to tacit knowing, the second
being the connection between knowing and personal skill. Given that Ryle argues
that knowing-how cannot be explained through knowing-that or grasp of a
proposition – both paradigmatic of what can be put into words – if, following
Polanyi’s second clue, tacit knowledge is equated with practical knowledge (of
which more below) then Ryle’s argument suggests limits to the way or purpose of
putting it into words. It cannot be explained
in knowing-that terms.
But, on the other hand,
the idea that practical knowledge can express intelligence directly – without
needing to inherit it from grasp of a proposition – suggests the following
thought which runs counter to Polanyi’s claim that we know more than we can
tell. (And thus it puts Polanyi’s two clues in tension.) Consider the following
piece of practical knowledge: the ability to recognise a raincoat as a
macintosh and thus denote it ‘macintosh’. Why is the denoting of raincoats as ‘macintoshes’
not what articulating or expressing this piece of recognitional knowledge
amounts to, thus discharging any tacit element? In this particular example,
because it involves linguistic denotation, why is that not putting all the
relevant knowledge in play into words
(calling this coat a ‘macintosh’,
eg.)? Why assume, as Polanyi does, that there is always a further, though
tacit, answer as to how one recognises that something is an instance of a
general kind?
These questions flag a
possibility that Polanyi neglects: that recognitional knowledge might both be
fully expressible (and thus, intuitively, not tacit in the sense of silent) nor
grounded in further tacit elements. But at the same time, Ryle does provide
support for the fundamental importance of the practical dimension. Might that
be used to justify a conception of tacit knowledge independently of Polanyi’s
own arguments?
I will address that
question by looking at a related regress argument which dates from about the
same time: Ludwig Wittgenstein’s discussion of rule following. Wittgenstein
considers what is grasped by someone who has grasped a mathematical rule or
series which he approaches via the idea of teaching the +2 series:
Now we get the pupil to
continue a series (say + 2) beyond 1000–and he writes 1000, 1004, 1008, 1012.
We say to him: “Look
what you’ve done!”–He doesn’t understand. We say: “You were meant to add two: look how you began the series!”–He
answers: “Yes, isn’t it right? I thought that was how I was meant to do it.”–Or suppose he pointed
to the series and said: “But I went on in the same way.”–It would now be no use
to say: “But can’t you see....?”–and repeat the old examples and
explanations.–In such a case we might say, perhaps: It comes natural to this
person to understand our order with our explanations as we should understand
the order: “Add 2 up to 1000, 4 up to 2000, 6 up to 3000 and so on.”
[Wittgenstein 1953: §185]
In passages such as
these, Wittgenstein seems to stress the infinite possibilities of divergence
and thus the infinite possibilities of a breakdown of communication. Given his
concurrent criticisms, in surrounding passages of the Philosophical Investigations, of appeal to physiological
mechanisms, mental talismans and platonic structures, objective features of the
structure of reality and independent of us, to explain our grasp of going on in
the correct way, it can seem the most fragile contingency that communication is
possible [cf Lear 1982]. The problem is the apparent mismatch between, on the
one hand, the idea of infinite range of rules and, on the other, the scanty
resources for teaching them.
Whence comes the idea
that the beginning of a series is a visible section of rails invisibly laid to
infinity? Well, we might imagine rails instead of a rule. And infinitely long
rails correspond to unlimited applications of a rule. [Wittgenstein 1953: §218]
But since teaching
rules is possible only either by paraphrase, which merely postpones the problem
of explaining the paraphrase, or by finite examples, which seem to
underdetermine the rule which governs a potentially unlimited number of cases,
grasp of a rule seems to need some further helping hand.
This line of thought
suggests, albeit mistakenly, a role for tacit knowledge. The thought runs:
since everything that can be said still allows for the kind of misunderstanding
exemplified by Wittgenstein’s hypothetical deviant pupil, the grasp of a rule
that a normal pupil acquires must be based on something unsaid and implicit. It
must depend on a tacit element. This seems to support Polanyi’s slogan that we
know more than we can tell. It can also seem to fit Wittgenstein’s own
conclusion:
What this shews is that
there is a way of grasping a rule which is not
an interpretation, but which is
exhibited in what we call “obeying the rule” and “going against it” in actual
cases. [ibid: §202]
The problem with this
thought is that it accepts what Wittgenstein opposes: an uncritical view of the
metaphor of rules as rails ‘invisibly laid to infinity’ fundamentally distinct
from our capacity to articulate them. This is a platonic view of the underpinnings
of our concepts which somehow latch onto the independent structure and is one
of Wittgenstein’s targets.
The platonic picture is
reinforced by one response to the cases of deviant pupils. They show, according
to this response, both that any finite set of examples underdetermines a
correct understanding of the rule but also that such correct understanding must
involve grasp of a structure which is independent of human judgement. Since no
actual human enumeration of the pattern seems enough to determine it, it must
be super-human. Hence the metaphor of rails laid to infinity. But whereas real
rails can bend and break, the rails in the metaphor cannot. They are
supernatural. With that picture of the way rules determine correct moves in
place, there is a substantial role for tacit knowledge to bridge the gap
between what can be made explicit in the sublunary realm and the ideal platonic
standard.
This picture is wrong
for two reasons, however. The first objection is that it undermines the
possibility of communication. If understanding depends on a combination of
something which can be expressed but which stops short of a rule and an
inexpressible tacit element which fills the gap, how can the right tacit
element be communicated in any particular case? The hybrid account cannot
escape the problem that the deviant pupil seems to raise. The deviant pupil
might fill in the gap with the wrong tacit element since nothing that can be
expressed is enough to guide the selection of tacit element.
The second objection is
that it is unnecessary. Whilst Wittgenstein rejects philosophical explanations
(via mental mechanisms or platonic structures) of our grasp of rules (by
pointing out they could not determine what they are supposed to), he does not
promote a kind of sceptical gap between what can be manifested and what must be
understood for communication, a gap that has thus to be filled by a tacit
element. To the contrary, he undermines the idea that there is any such gap in
the first place. For example, he argues that there is a conceptual connection
between what a teacher can express and what a student can grasp in the examples
which manifest the teacher’s meaning.
“But do you really
explain to the other person what you yourself understand? Don’t you get him to guess the essential thing? You give him
examples,--but he has to guess their drift, to guess your intention.” – Every
explanation which I can give myself I give to him too. – “He guesses what I
intend” would mean: various interpretations of my explanation come to his mind,
and he lights on one of them. So in this case he could ask; and I could and
should answer him. [ibid: §210]
“But this initial
segment of a series obviously admitted of various interpretations (e.g. by
means of algebraic expressions) and so you must first have chosen one such interpretation.”–Not at all. A
doubt was possible in certain circumstances. But that is not to say that I did
doubt, or even could doubt…[ibid: §213]
Recognising that
understanding can be expressed in examples, for those with eyes to see at
least, undermines the idea that there is a gap between sublunary explanations
and rules understood as platonic structures and thus a need, there, for tacit
knowledge to bridge that gap. A finite series of examples, or a particular
verbal explanation, or even a signpost, can express the very rule in question
without the need for an underlying tacit interpretation. Thus there is no
support in Wittgenstein’s discussion of understanding for Polanyi’s slogan that
we know more than we can tell. What we know, we can express and in the case of
denotation, put into words.
Wittgenstein’s
discussion also suggests a response to Polanyi’s assumption that the focal
recognition of one thing depends on tacit or subsidiary awareness of something
else. If the role of the subsidiary elements serves as the tacit grounds for an
understanding of what is focally recognised, if they provide a kind of
interpretation of it, then Wittgenstein’s discussion undermines that picture.
The account of understanding as depending on a combination of an explicit and a
tacit elements cannot be generally true. This, thus, undermines the motivation
for Polanyi’s arguments in the previous section. Polanyi does not provide a
reason to think that recognitional judgement is tacit nor to think that acts of
denotation do not fully manifest one’s recognitional know-how.
But whilst Ryle’s and,
especially, Wittgenstein’s regress arguments do not support a connection
between tacit knowledge and inexpressibility, they do suggest an important link
between the practical groundings of knowledge and a more modest construal of
the slogan that we know more than we can tell.
Consider a rule which
can be partly codified in an informal statement such as that the digits always
follow the pattern: ‘0, 2, 4, 6, 8, 0 etc’ or more fully codified in an
explicit mathematical formula or principle. Someone who understands such a rule
may understand a general principle or perhaps a set of related principles using
some of them to explain others. They may thus be able to articulate what they
understand the rule to be in general and context-independent terms.
Nevertheless, even with such a codifiable rule, understanding it cannot be
independent of understanding its instances. One needs to know, in Wittgenstein’s
phrase, how to go on.
Wittgenstein gives an
example of someone who grasps a series either with, or without, having a
formula in mind:
It is clear that we
should not say B had the right to say the words “Now I know how to go on”, just
because he thought of the formula – unless experience shewed that there was a
connexion between thinking of the formula – saying it, writing it down – and
actually continuing the series...
We can also imagine the
case where nothing at all occurred in B’s mind except that he suddenly said
“Now I know how to go on” – perhaps with a feeling of relief; and that he did
in fact go on working out the series without using the formula. And in this
case too we should say – in certain circumstances – that he did know how to go
on. [ibid: §179]
The passage makes a
connection between understanding and an ability to take part in a practice
explicit. But there is also something implicit in this example. It involves particular cases. Whatever the general
criteria there may be for understanding a rule, such as restating or
summarising it in general terms, such understanding also requires grasp that this particular
number, for example, is the next number in the sequence. One needs to know that
how to recognise or proffer a particular number which – whatever its size,
colour and font – counts as an instance of the rule because it is an instance
of the next number, for example 8.
This is the connection
that lies at the heart of the rule following considerations. Understanding of a
general rule involves the ability to recognise particular cases. The regress
argument targets attempts to explain this connection in non-practical terms. It
undermines putative explanations of the practical ability to recognise new
cases as instances of a general rule in other terms such as by invoking
sub-personal mechanisms or supernatural and platonic structures. But as the
example of the deviant pupil shows, when one abstracts away from our actual
shared abilities and responses, it is impossible to recover what is understood
when one understands a rule. Nothing impersonal can capture the way a subject
can see in the examples given a general rule and then recognise new instances
as going on in the same way. Thus both Ryle and Wittgenstein share an emphasis
on what I called Polanyi’s second clue: the practical groundings of knowledge.
But the regress
arguments also suggest a qualified version of the first clue, especially as it
applies both to recognition and more explicitly practical knowledge. The point
is not that such knowledge cannot be expressed but that it cannot be expressed
in context-independent terms. Practical knowledge requires context-dependent
sensitivity. This suggests a way to draw on Polanyi’s suggestions, if not his
explicit arguments, for tacit knowledge. Tacit knowledge is best thought of as
context-dependent practical knowledge or ‘personal knowledge’ in Polanyi’s
phrase. Further, if the regress argument is correct, it lies at the heart of
explicit knowledge that can be articulated or codified in context-independent
terms.
So understood, it also
seems relevant to psychiatric diagnosis. In particular, it is relevant to the
dominance of the criteriological approach to diagnosis and its attempt to
underpin reliability. The moral of the regress argument is that there are
limits to the extent to which this can be achieved since codification rests on
a bed of practical skills.
Tacit knowledge, clinical judgement recognition
and psychiatric symptoms
I began by outlining
the importance of reliability and thus the stress on operationalism for
psychiatric taxonomy and diagnosis. For the last half century, syndromes have
been defined in terms of conjunctions and disjunctions of symptoms which have
themselves been described in terms as free of aetiology as practical. (For some
conditions, such as PTSD, that would be impossible.) Thus the diagnosis of a
specific syndrome is justified in a particular subject if he or she has enough
of the relevant symptoms.
This approach is aimed
at closing the principled gap between syndrome and subject and thus increasing
inter-rater reliability among clinicians. Because of the way both ICD and DSM
base syndromes on a combination of conjunction and disjunction of symptoms, it
is possible that a syndrome so defined may apply to two individuals with little,
or even no, overlap of symptoms. But these differences are codified rather than
left to an overall uncodified clinical judgement. Further, the heritage of
operationalism suggests a hope that individual symptoms can be tied to subjects
through a kind of measuring operation.
There remains, however,
a potential gap between the textbook or diagnostic manual articulation of a
symptom and a presenting individual. The concepts of specific symptoms are,
despite their specificity, general concepts that can be instantiated in an
unlimited number of actual or potential cases. So how can one judge that a
general concept applies to a specific individual case or individual person? How
can one recognise that the individual exemplifies a type?
One can attempt to bridge
this apparent gap in purely general and impersonal terms so as to codify
psychiatric expertise. Textbooks of psychiatry can describe, rather than merely
list, symptoms. But whatever descriptive account they give of symptoms, there
will always be a distinction of kind between their general descriptions and
concepts (which potentially apply to any number of individuals) and any
particular presenting individual who may or may not exemplify or instance them.
Determining that they do instance or exemplify such general concepts calls for
clinical judgement.
The regress arguments
from the previous section suggests that there are limits to the extent to which
operational definitions or criteriological approaches to diagnosis can, in a
quest for reliability, exclude the exercise of skilled individual judgement. It
is thus worth noting that there has been something of an anti-operationalist
backlash within psychiatry.
Criticising the ability
of the DSM criteria to capture the nature of schizophrenia, Mario Maj, for
example, argues that:
One could argue that we
have come to a critical point in which it is difficult to discern whether the
operational approach is disclosing the intrinsic weakness of the concept of
schizophrenia (showing that the schizophrenic syndrome does not have a
character and can be defined only by exclusion) or whether the case of
schizophrenia is bringing to light the intrinsic limitations of the operational
approach (showing that this approach is unable to convey the clinical flavour
of such a complex syndrome). In other terms, there may be, beyond the
individual phenomena, a ‘psychological whole’ (Jaspers, 1963) in schizophrenia,
that the operational approach fails to grasp, or such a psychological whole may
simply be an illusion, that the operational approach unveils. [Maj 1998:
459-60]
In fact, Maj favours
the former hypothesis. He argues that the DSM criteria fail to account for
aspects of a proper grasp of schizophrenia, for example, the intuitive ranking
of symptoms (which have equal footing in the DSM account). He suggests that
there is, nevertheless, no particular danger in the use of DSM criteria by
skilled, expert clinicians for whom it serves merely as a reminder of a more
complex underlying understanding. But there is problem in its use to encode the
diagnosis for those without such an additional prior understanding:
If the few words
composing the DSM-IV definition will probably evoke, in the mind of expert
clinicians, the complex picture that they have learnt to recognise along the
years, the same cannot be expected for students and residents. [ibid: 460]
Maj’s criticism that
the DSM criteria do not capture a proper, expert understanding of the diagnosis
of schizophrenia raises the question of how or why that could be the case. If
the criticism is right, is it that the wrong criteria have been used: either
the wrong symptoms and / or the wrong rules of combination? Or is there
something more fundamentally wrong with the criteriological approach as applied
to psychiatry? Josef Parnas suggests the latter. In a paper describing
pre-operational approaches to taxonomy and diagnosis as a ‘disappearing
heritage’ he comments on an underlying difference in attitude towards signs and
symptoms of schizophrenia.
When the pre-DSM-III
psychopathologists emphasized this or that feature as being very characteristic
of schizophrenia, they did not use the concept of a symptom/sign as it is being
used today in the operational approach. This latter approach envisages the
symptoms and signs as being (ideally) third person data, namely as reified
(thing-like), mutually independent (atomic) entities, devoid of meaning and
therefore appropriate for context-independent definitions and unproblematic
assessments. It is as if the symptom/sign and its causal substrate were assumed
to exhibit the same descriptive nature: both are spatio-temporally delimited
objects, ie, things. In this paradigm, the symptoms and signs have no intrinsic
sense or meaning. They are almost entirely referring, ie, pointing to the
underlying abnormalities of anatomo-physiological substrate. This scheme of ‘symptoms
= causal referents’ is automatically
activated in the mind of a physician confronting a medical somatic illness. Yet
the psychiatrist, who confronts his ‘psychiatric object’, finds himself in a
situation without analogue in the somatic medicine. The psychiatrist does not
confront a leg, an abdomen, not a thing, but a person, ie, broadly speaking,
another embodied consciousness. What the patient manifests is not isolated
symptoms/ signs with referring functions but rather certain wholes of mutually
implicative, interpenetrating experiences, feelings, beliefs, expressions, and
actions, all permeated by biographical detail. [Parnas 2011: 1126]
The claim here is that
the criteriological approach has the wrong model of psychiatric symptoms and
signs in two respects. Just as smoke can mean fire or tree rings the age of a
tree, the criteriological approach takes signs to be free standing items which
causally indicate underlying states. (Smoke is distinct from, but can be caused
by, fire and so in a particular context smoke can factively mean fire.)
Furthermore, these relations are independent of one another: they are atomic.
By contrast, Parnas suggests, psychiatric signs and symptoms are both essentially
meaning-laden and also mutually interdependent wholes. It is the latter claim
which plays the more important role in his criticism.
One argument for their
interdependence is that it is only in particular contexts that symptoms are
reliable. Thus, for example, mumbling speech is comparatively widespread
(Parnas estimates 5% of the population) but in – and only in – the context of
other features such as ‘mannerist allure, inappropriate affect, and vagueness
of thought, it acquires a psychopathological significance’ [ibid: 1126]. So the
effectiveness of the sign is context-dependent. In some contexts it is
indicative and in others not. But Parnas goes further by suggesting a more than
merely additive view. Grasp of psychiatric symptoms is an overall gestalt
experience, likened to seeing the figure of the duck-rabbit first as a rabbit
and then suddenly as a duck: seeing the signs and symptoms under an overall
aspect.
A Gestalt is a salient
unity or organization of phenomenal aspects. This unity emerges from the
relations between component features (part-whole relations) but cannot be
reduced to their simple aggregate (whole is more than the sum of its parts)...
A Gestalt instantiates a certain generality of type (eg, this patient is
typical of a category X), but this typicality is always modified, because it is
necessarily embodied in a particular, concrete individual, thus deforming the
ideal clarity of type (universal and particular). [ibid: 1126]
So the model of
diagnosis is one in which the skilled clinician gasps the right diagnosis as a
whole in which different aspects can be seen as abstractions from that whole
rather than as its basic building blocks. Such a view would accommodate Maj’s
suggestion that criteriological elements serve as reminders for already skilled
clinicians. They do – on this view – in the sense that after the fact, such
articulations of the overall picture are possible, as a musical note may be
divided into its pitch, tone and duration whilst it cannot be built up from
those as independent building blocks. But that does not imply that the expert
judgement of the whole could be built up from the individual criteria
understood in isolation.
I think that this is
also the clue to understanding the nature of Parnas and his colleagues recent
EASE project: the Examination of Anomalous Self-Experience. Prima facie, this
might seem to be merely a more detailed version of a criteriological approach
with a more thorough description of symptoms in a forlorn attempt to eliminate
the need for clinical judgement in bridging the gap between general description
and particular presenting individual. It is, after all, described by them thus:
The Examination of
Anomalous Self-Experience (EASE) is a symptom checklist for semi-structured,
phenomenological exploration of experiential
or subjective anomalies that may
be considered as disorders of basic or ‘minimal’ self-awareness. [Parnas et al
2005: 236]
But despite this, the
EASE approach stresses the need for flexible conversational relations between clinician
and patient or client, rather than a structured interview, and the development
of practical recognitional skills:
The interviewer must
possess good prior interviewing skills, detailed knowledge of psychopathology
in general and of the schizophrenia spectrum conditions in particular, and he
should pass an EASE 3-day training course, comprising (1) a 1-day theoretical
seminar, (2) a number of supervised interviews and (3) provisional assessment
of reliability. [ibid: 239]
In other words, the
reliability of the method is underpinned by shared practical judgements as well
as theoretical knowledge and fits Parnas’ stress on a gestalt or holistic view
of the nature of diagnosis rather than a criteriological view.
To what extent, then,
does this alternative approach depend on tacit knowledge? There are two reasons
to think of the kind of diagnostic judgement outlined by Parnas as relying on
tacit knowledge in the way I have described it: as context-dependent practical
knowledge. First, and negatively, is the claim that the expertise involved
cannot be codified in context-independent terms, as the DSM and ICD criteria
require. But second, recognising a diagnostic whole as a kind of gestalt, seen
with its own internal organisation, is an example of the same kind of judgement
involved in recognising a new case as an instance of a grasped, prior rule or
concept: an essentially context-sensitive judgement.
Maj’s criticisms of the
operational criteria for schizophrenia and Parnas’ opposing view of the nature
of diagnosis more generally suggest an alternative view of how diagnostic
reliability might be achieved. The operational approach attempts to codify
psychiatric expertise and thus play down a role for a tacit dimension in
clinical expertise. But philosophical analysis suggests that this project could
never be completed. There is no alternative to a practical judgement, of ‘how
to go on’, in Wittgenstein’s phrase. The alternative accepts that diagnostic
judgement cannot be so codified and takes it instead to be an exercise of
skilled recognitional clinical judgement, a form of tacit knowledge under the most plausible understanding of that phrase.
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