Reductionism:
theory - a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena; "theories can incorporate facts and laws and tested hypotheses"; "true in fact and theory"
analytic thinking, analysis - the abstract separation of a whole into its constituent parts in order to study the parts and their relations."
http://www.thefreedictionary.com/reductionism
"In philosophy, reductionism is a theory that asserts that the nature of complex things is reduced to the nature of sums of simpler or more fundamental things.
This can be said of objects, phenomena, explanations, theories, and meanings.
Reductionism is often understood to imply the unity of science."
http://en.wikipedia.org/wiki/Reductionism
Note:
"It has been said: The whole is more than the sum of its parts. It is more correct to say that the whole is something else than the sum of its parts, because summing up is a meaningless procedure, whereas the whole-part relationship is meaningful."
(Kurt Koffka, 1935: Principles of Gestalt Psychology. New York: Harcourt-Brace. p 176) "
http://www.geocities.com/Athens/Cyprus/2926/sum.html
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