Social Research Glossary


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Citation reference: Harvey, L., 2012-20, Social Research Glossary, Quality Research International,

This is a dynamic glossary and the author would welcome any e-mail suggestions for additions or amendments. Page updated 19 December, 2019 , © Lee Harvey 2012–2020.


A fast-paced novel of conjecture and surprises



core definition

Complementarity essentially means that alternative conceptualisations of perceived phenomena complement one another and are mutually exclusive.

explanatory context

Complementarity is a term that evolved in physics as a means to reconcile the differences between classical and quantum description in physics in the early part of 20th Century.


For example, an atomic entity could not exhibit its particle properties and its wave properties simultaneously. They could both be ‘obsesrved’ as complements but no theoretical scheme could incorporate both sets of properties and hence no ‘observation’ mechanism could provide for simultaneous display of both sets of properties.


Indeed, it was the problem of observation in atomic physics that made the differences between classical and quantum physics so difficult to reconcile. Classical physics tended to accept that its theories were grounded on incontrovertible evidence. Quantum physics was acutely aware of the problem of the theory-laden nature of observation because in the atomic domain there is no way of separating the observer and his or her equipment from the observation being made.


Observation in atomic physics is recognised as a combination of observer and object, not only in the sense that the observer has a set of prior expectations, theories, values etc., in the light of which the observation is made, but in an ‘objective’ sense too. The very act of observation affects the outcome. For example; Heisenberg’s gamma ray microscopic ‘watches’ by scattering gamma rays from an electron, thus deflecting the electron from its original path.


For Bohr, who developed the concept of complementarity in view of the void between the two physics, the ‘object’, the observer and his and her equipment formed an inseparable whole.


Bohr’s proposal leads to an inevitable question of ultimate resolution. Does complementarity simply imply that alternative conceptualisations have to be admitted but also permitted to happily co-exist? Or does it offer a method of framing incompatible points of view with a view to a future synthesis?


Bohr argued that apparently paradoxical and contradictory accounts of nature should be faced up to and not glossed over and that a complementary mode of description was essential. Unlike the situation in earlier periods, clarity does not reside in simplification and reduction to a single, directly comprehensible model, but in the exhaustive overlay of different descriptions that incorporate apparently contradictory notions.


While this provides no definite answer, it infers that a synthetic reduction is possible. But such synthesis must involve a qualitatively different perspective. It implies something more than mere resolution. (The resolution of Galileo and Newton was not synthetic in the sense of a qualitative shift. It was a resolution through the principle of unification, it subsumed one thesis under another in order to unify science). Complementarity involves ‘concept juggling’. The ability to view the whole through its complementary perspectives and then to effect a synthesis requires divesting phenomena of constraining concepts. In short, as I noted in 1998, a complementarity approach has remarkable similarities to a dialectical analysis (although this is rarely admitted by philosophers of science).



analytical review

Katsumori (2011, p. 107) claims that :

Bohr's dynamic conception of complemtarity in quantum theory as well as other fields is found to be in close proximity to Ricouer's dialectic of event and meaning.

associated issues


related areas

See also



Katsumori, M., 2011, Niels Bohr's Complementarity: Its Structure, History, and Intersections with Hermeneutics and Deconstruction. Boston Studies in the Philosophy of Science, 286, Dordrecht, Springer.

copyright Lee Harvey 2012–2020


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