Function follows form

Form follows function is a principle associated with modern architecture and industrial design in the 20th century. The principle is that the shape of a building or object should be primarily based upon its intended function or purpose.

Is ornamentation "functional"?
In 1908 the Austrian architect Adolf Loos famously proclaimed that architectural ornament was criminal, and his essay on that topic would become foundational to Modernism and eventually trigger the careers of Le Corbusier, Walter Gropius, Alvar Aalto, Mies van der Rohe and Gerrit Rietveld. The Modernists adopted both of these equations—form follows function, ornament is a crime—as moral principles, and they celebrated industrial artifacts like steel water towers as brilliant and beautiful examples of plain, simple design integrity.

These two principles—form follows function, ornament is crime—are often invoked on the same occasions for the same reasons, but they do not mean the same thing. If ornament on a building may have social usefulness like aiding wayfinding, announcing the identity of the building, signaling scale, or attracting new customers inside, then ornament can be seen as functional, which puts those two articles of dogma at odds with each other.

Conversely the argument "ornament is crime" does not say anything about function. It is an aesthetic preference inspired by the Machine Age. While human performance may be enhanced by a sense of well-being endowed by aesthetic pleasure, machines have no such need of beauty to perform their work tirelessly. Ornament becomes an unnecessary relic, or worse, an impediment to optimal engineering design and equipment maintenance. Other stylistic "non-functional" features may rest untouched (e.g., the feeling of space, the composition of the volumes) as we can see in the subsequent abstracted and non-ornamented styles. Much of the confusion between these two concepts comes from the fact that ornament traditionally derives from a function becoming a stylistic character (e.g., the gargoyle from Gothic cathedrals).

Modernism in architecture began as a disciplined effort to allow the shape and organization of a building to be determined only by functional requirements, instead of by traditional aesthetic concepts. It assumes that the designer will determine empirically (or decide arbitrarily) what is or is not a functional requirement. The resulting architecture tended to be shockingly simpler, flatter, and lighter than its older neighbors, possibly due to the limited number of functional requirements upon which the designs were based; their functionality and refreshing nakedness looked as honest and inevitable as an airplane. Modernists believed, perhaps incorrectly, that airplane design did not involve any aesthetic decisions by the airplane designers. A recognizable Modern vocabulary began to develop.

imformation from
http://en.wikipedia.org/wiki/Form_follows_function