Unknowns: three kinds

The matrix below provides a useful way of distinguishing between three primary categories of unknowns. The most familiar is ignorance that we are aware of, the ‘known unknowns’. Most research addresses this kind of ignorance, seeking to fill known knowledge gaps.

Another kind of unknown is knowledge that we do not know we have, the ‘unknown knowns’ or tactic knowledge. Culturally appropriate behaviour is a good example.

The third kind of ignorance is what we do now know we do not know, the ‘unknown unknowns’. We generally become aware of unknown unknowns in two ways. On a societal level unknown unknowns are exposed through hindsight, after an event, for instance, has caught us by surprise. For example before 2003, the communicable disease SARS was an unknown unknown—as a society we did not know that such a disease was developing and would strike. On an individual or community level, unknown unknowns can be exposed by interacting with people outside our usual circles, opening the potential for their knowledge to reveal 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) that use various varieties of rice can expose my unknown unknown.


  Known Unknown
Known Known knowns Known unknowns (conscious ignorance)
Unknown Unknown knowns (tacit knowledge) Unknown unknowns (meta-ignorance)

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



  • Bammer, G. (2013a). 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

Posted: January 2016
Last modified: January 2016