Two of his studies explored the difficulties scientists faced in replicating experiments
successfully carried out by others (Collins 1974, 2001b).
Tacit knowledge was
evident where teams could perform the experiments, but were unable to transmit that
to other because in fact they were unaware of the real reasons for their success.
In

OKLC 2002 - Athens: Gourlay
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both instances it turned out that features of the experimental set-up they regarded as
marginal or routine practice, and hence overlooked in reporting their results, were
critical to success of the experiment.
This was only discovered when teams worked
together, and each gradually learned what the critical factors were.
Tacit knowledge can only be passed on only by personal contact. Collins identified
five types of such knowledge (Collins 2001b: 72-3):
concealed knowledge
tricks of the trade; concealment may be intentional or
unintentional (the concealer is unaware)
mismatched salience
different parties focus on different variables or aspects of
a complex piece of research, resulting in mismatched
perspectives
ostensive knowledge
words may not be available to convey knowledge that
pointing can
unrecognized knowledge
the successful experimenter may be unaware of critical
actions that an observer successfully but unconsciously
imitates
uncognized/uncognizable
knowledge
our ability to utter meaningful sentences without being
able to say how; learning requires apprenticeship
We can reasonably infer that all but the last category of these types can be made
explicit in some form. Concealed and unrecognized knowledge, as in the examples
above, can be spoken about once exposed, or recognized; things known ostensively
can be named, and words used to refer to them, and different parties to an activity or
experiment can come to recognize that they were both dealing with the same thing.
Collins has recently explored the question of making tacit knowledge explicit.
Many
examples of tacit knowledge fall into what he called the motor-skills category.
This is
exemplified by riding a bicycle or performing any such similar skill.
A second group
he called the rules-regress model, and is based on Wittgenstein's observations about
rule-following.
The third category is what he called the 'forms of life' approach.
People in different social groups take different things to be knowledge, but are
unaware of the social basis of their certainties.
Thus, if the true sources of our beliefs
are largely social, yet we do not recognize this, then, he claims, the sources of our
beliefs are hidden from us, and thus based on tacit understandings (Collins 2001a:
110-1).
Collins argues that there is nothing philosophically fundamental about the motor-
skills and rules-regress forms of tacit knowledge since advances in neural net
computing make it possible to incorporate both types into a non-symbolic computer
program from where, in principle, it might be possible to derive a symbolic computer
program.
On the other hand, the ‘forms of life’ type of tacit knowledge is beyond the
