Unknowns: three kinds

Purpose: To distinguish among three primary categories of unknowns.

Description: One useful way of thinking about different kinds of unknowns is illustrated in the matrix below, which highlights three kinds of unknowns: known unknowns, unknown knowns and unknown unknowns.


Adaptation by Michael Smithson of Kerwin (1993), published in Bammer et al., (2008); Also described in Bammer (2013).

The most familiar is what we know we do not know ie ‘known unknowns’ or conscious ignorance. Most research addresses this kind of ignorance, seeking to fill known knowledge gaps.

Unknown knowns or tactic knowledge is knowledge that we are largely unaware that we have. Culturally appropriate behaviour is a good example. It is usually not until we are exposed to another culture that we become attentive to what we know about how to behave in our own culture. In particular, we become aware that we have a store of knowledge about how to be polite, what behaviours are unacceptable, gestures that are offensive and so on.

The third kind of ignorance is what we do not know we do not know, the ‘unknown unknowns’. We generally become aware of unknown unknowns through surprise. There are two kinds of unknown unknowns: false convictions and unknowns we are not aware of at all (Smithson, 2019).

False convictions can be overturned by a credible source. On an individual or group basis this can be aided by interacting with people outside the usual circles, opening the potential for their knowledge to expose an unknown unknown. For example, if I ‘know’ there is only one kind of rice, mixing with people from an ethnic culture or occupation (eg chefs) who use various varieties of rice can expose my unknown unknown.

Unknowns that we are not aware of at all are generally exposed by hindsight, after an event, for instance, has caught us by surprise. For example, before the 1980s, the communicable disease HIV/AIDS was an unknown unknown—as a society we did not know that such a disease was developing and would strike.



  • Bammer, G. (2013). Disciplining Interdisciplinarity: Integration and Implementation Sciences for Researching Complex Real-World Problems. ANU Press: Canberra, Australia (Online: http://press.anu.edu.au/publications/disciplining-interdisciplinarity)
  • Bammer G., Smithson, M. and the Goolabri Group. (2008). The Nature of Uncertainty. In Bammer, G. and Smithson, M. (eds.) Uncertainty and Risk: Multi-Disciplinary Perspectives. Earthscan: London, United Kingdom, pp: 289-303
  • Kerwin, A. (1993). None too Solid: Medical Ignorance. Science Communication, 15, 2: 166-185
  • Smithson, M. (2019) How can we know unknown unknowns?

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Posted: January 2016
Last modified: March 2021