Complementarity

For thoughtful child sponsors

Complementarity is a concept in economics similar to that of externality. Two goods are complements if their cross elasticity of demand is negative. That is, as the price of one good increases, the demand to the other good decreases. When a large number of complementary products are interconnected, network externalities can arise. In general, complementarity exists when the decisions of other economic agents changes how I value things.

A good example of a complementarity is the example of keyboards. Virtually all keyboards use the QWERTY style, which was created so that typewriters wouldn't jam. Other styles include that promoted by Dvorak. Because QWERTY keyboards are so popular, an individual values it more than the one proposed by Dvorak, even though there is no reason to believe QWERTY to be inherently superior.

In Physics, "complementarity" is a basic principle of quantum theory. Wave(field) and particle are perspectives in a relationship of complementarity. Term first used in this sense by William James in terms of the dual perpectives of freedom and determinism. If you ask operationally, are we determined, the answer is YES, but this does not then imply that we are NOT FREE. We must ask the independent operational questions, are we free.

To ask of an entity, are you are particle, the operational answer is yes, whether you be an electron or a photon. Likewise, to ask of an entity, are you a wave, the operational answer is yes. However, you are prohibited by nature to ask both questions simultaneously; the operations preclude each other.

The Principle of Complementarity: Reality is such that one single, logically consistent explanatory system will not suffice. More than one such explanatory systems are needed, which are in a relationship of complementarity - the use of one perspective precludes the simultaneous use of the other perspective. This may be one of the most significant discoveries of the 20th century, known by very few and ignored by all.

This article is a stub. You can help Wikipedia by expanding it.