What is tacit knowledge?

"Tacit knowledge" is remarkably difficult to define and its meaning is often contested. Certainly it is something that is known but that is cannot be verbally articulated. It does not easily express itself in the rigid formality of language (especially when written), it is difficult to convey and, as such, is non communicable. The phrase "tacit knowledge" has been used in a broad variety of senses and, for the scope of this write up, it is necessary to distinguish what is meant by it. There are two main types of so-called tacit knowledge: things yet to be put into words (such as trade secrets or specific skills that have been overlooked as important or relevant) and things that are inherently inexpressible in words (relating to the senses such as the feeling of sufficiently kneaded bread or the timbre of a well-manufactured musical instrument). The first category has no insuperable barrier that prevents the knowledge from being made explicit and then exchanged. The knowledge has been concealed whether intentionally or not, but there is no reason why it should not be shared and communicated. This need not be tacit. However, the second stricter type includes things such as the open-textured nuances of expected social conduct and knowledge that can only be learned by familiarity. It is argued that this knowledge can only be transmitted by personal contact or experience and not via media such as books or manuals. Collins defines tacit scientific knowledge as "knowledge or abilities that can be passed between scientists by personal contact but cannot be, or have not been, set out or passed on in formulae, diagrams, or verbal descriptions and instructions for action" and it is this type that shall be the main topic of discussion in this write up.

Why is it tacit knowledge?

Why should some information be easily communicable while certain types of knowledge are formed of tacit rules that are impossible to formulate? I can transfer the first 740 digits of pi by simply storing the information as ink marks on a piece of paper and handing it over to someone. Anyone who has learned the rules for how to interpret decimal notation using Western numerals will have gained the knowledge without ever having to have met me. However, it is infeasible for me to write down the rules for learning to cycle for someone unable to ride a bicycle. There is no set formula that can be followed that will certainly result in a competent cyclist. Very few useful comments regarding technique can be written down and beginner cyclists find instructions to be of little use. There is no easy way to pass on the formula for riding a bike – the only way to successfully corner and balance at different speeds is through sufficient practice and experience. It is also interesting to note a characteristic of tacit knowledge – the only genuine test for it is in the doing itself. There is no real way for a cyclist to proof that they are capable of riding a bicycle without actually doing so. Likewise tacit knowledge about something is best demonstrated by using the actual knowledge.

Scientific tacit knowledge and the TEA laser

This idea is important in science because experimental science relies on the reproduction of results and corroborating data. Both modern and ancient experiments have always been complicated and fiddly - even those without technological complexities. For the independent duplication of results that is required to support theories, the knowledge needed to perform the experiment must be transferred between groups. Polanyi failed to make the unequivocal observation that the possession of tacit knowledge is not restricted to individuals. However, it is apparent that the difficulties in communicating knowledge between research groups is integral to scientific progress. Much of science is too difficult to organise coherently. Scientists often give the all-too-often-false impression that algorithmic instructions will be carried out identically and produce similar responses in nature. They assume that practical experiments are a formality when this is rarely the case. Collins states that "all types of knowledge, however pure, consist, in part, of tacit rules that may be impossible to formulate in principle" and has performed a lot of work studying the case of manufacturing TEA (Transverse Electrical discharge in gas at Atmospheric pressure) lasers.

The construction of the first TEA laser involved significant trial and error and apparent duplicates fail to work at all or only unpredictably and sporadically. Several teams methodically followed the instructions of the inventors only to find that, no matter how meticulous they were, they could not make a working model. However, when scientists and technicians joined the other sucessful teams they eventually helped them to construct functional lasers. Building a working laser appears to be impossible without the personal transfer of necessary tacit knowledge. Collins claims that no successful TEA laser|TEA lasers were produced using only published and other written sources. Laboratories constructed working lasers after organising the transfer of personnel for an extended period of time. No laser was successfully constructed relying only on knowledge or contact with someone who had not built their own functioning laser – it appears that the experience of assembling an operative TEA laser supplies the tacit knowledge required to build more lasers. Apart from reinvention, the only way for another group to make a TEA laser is by personal contact with someone with this tacit knowledge.

The idea of tacit knowledge also encompasses mismatched salience or the focus by different parties on different variables. Tacit knowledge is evident where teams can perform certain experiments but are unable to transmit that to others because they are unaware of the real reasons for their success. Some features of the experimental set-up were critical to its success but were regarded as marginal or routine, and hence were overlooked in reporting the results. Originally, the critical factors were unintentionally concealed but, when teams work together they can gradually learn what they are.

Digression: tacit knowing

In his writing on the subject, Polanyi uses the phrase "tacit knowing" far more frequently than "tacit knowledge". There is a subtle but distinct difference between these two formulations. Tacit knowing is rarely denied because knowing is the process of learning something through experience and practise. However, tacit knowledge is a different matter – it is knowledge or information that can only be transferred tacitly. Learning the taste of a good pint is something that can only be tacitly learned but it can be argued that the knowledge required to brew a high quality beer is expressible without personal contact. Good brewers use tacit knowledge gleaned through years of experience but it may be technically possible to create precise instructions regarding the fermentation process so that a novice could produce an equally refreshing ale. However, the sheer volume of incredibly detailed information that needs to be transmitted is too large to make it practical. In addition, if knowledge is defined as "warranted (and not merely logically justified) true belief", then tacit knowledge must be warranted too. It is difficult to see how something can be warranted without first being made explicit. In any case, Polanyi was concerned with a process or activity rather than a type of knowledge and it is the tacit learning that is of greatest interest rather than the knowledge itself.


In science through the ages, the transfer of tacit knowledge has been essential to advancement and the development of successful theories. It is clear that meteorologists, for example, can predict the weather without applying algorithms to atmospheric readings and without necessarily being aware of or able to say how they did it. Even if they can to describe how they do it, their awareness does not have to be an analytically sophisticated one. Polanyi probably goes too far in suggesting that tacit knowledge allows people to anticipate the solution to problems, but it is certainly important. Tacit knowledge allows one to see the "thousand varied and changing clues" of a moving object "jointly as one single unchanging object" and recombine the gestalt. The fact that certain skills can only be transferred by physical meetings and cooperation means that the continuation of certain technologies is only possible when people or groups acting nodes with the tacit knowledge exist to spread the required information through the network of scientists.

  • Collins, H.M. Changing Order: Replication and Induction in Scientific Practice (London, 1985).
  • Collins, H.M. "The TEA Set: Tacit Knowledge and Scientific Networks", Science Studies, 4, pp. 165-86 (1974).
  • MacKenzie, D.A. and Spinardi, G. "Tacit Knowledge, Weapons Design, and the Uninvention of Nuclear Weapons", American Journal of Sociology, 101, pp. 44-99 (1995).
  • Polanyi, M. Personal Knowledge: Towards a Post-Critical Philosophy (London, 1958).

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