Some of Rem Koolhaas' words [from Final Push in SMLXL] regarding contextualism and rationalism.
"Contextualism
The central moment of the contextualist epiphany is the collision of a projected ideal with an empirical necessity. Insofar as the latter transforms the former and dampens its utopian tendencies, the contextualist derives not only aesthetic pleasure, but also-more importantly a degree of antimetaphysical comfort.
A contradiction lies at the heart of contextualist design: in the contextualists' favorite examples, these collisions and aborted utopias are literally generated by the course of events over long periods of time; but the modern contextualist is forced to telescope vicissitudes of centuries into a single moment of conception. In an act of more-or-less inspired projection, the contextualist generates a scenario that simulates the history of the next 400 to 500 years. Through this extrapolation in the name of history, the contextualist short-circuits historical continuity.
A second problematic area is that of empirical necessity. In simulating the aesthetics of history single-handedly, the contextualist must impersonate - with equal conviction - both sides in the reenactment of the eternal battle between the ideal and the real, the Platonic and the circumstantial. The contextualist's search for empirical necessity - the circumstantial forces that will inflect the pure model - can become frantic. The existing is squeezed for its maximum potential to inspire imperfection and cause impurity; it is forced to carry assumptions and speculations that it can hardly support and is thus subjected to an idealization in reverse. The circumstantial becomes another utopia, with a subsequent loss of precisely that aura of concreteness and specificity that the contextualist doctrine set out to maintain.
Finally, since the contextualist, a Popperian, does not believe in utopia, the contextualist's aesthetic lacks exactly that dourness that would make its violation a drama. In both its preemptive aspect and its perverse idealization of the empirical, contextualism actually precludes a series of more complex and precise choices that could bring the actual context into focus.
Rationalism
The appeal of rationalism lies in the chaste economy of the imagination that it postulates: it asserts that it is redundant and even dangerous to invent or replace forms of urban organization - the street, the plaza, etc. - that have been perfected over centuries. Within this restoration of sanity, it is disconcerting that everything the 20th century contributed to the historic sequence - new types that are demonstrably responses to authentic programmatic demands and inspirations - is excluded. Through this arbitrary closure, the infinitely reassuring dream of a world inhabited by a known series of typologies and morphologies, endowed with eternal life and capable of absorbing all programs, turns ominous when, for instance, Gunnar Asplund's Stockholm Public Library is shamelessly recycled in Luxembourg as the new European Parliament.
With such theories, culture is at the mercy of an arsenal of procrustean types who censure certain activities and expressions with the simple excuse that there is no room for them and at the same time proclaim the continuing validity of others simply because they do not disrupt the continuity of the urban texture. (In the Parliament competition, for instance, the program included a 5,000 m2 conference center. For such elements, there is no typology.)
With their obsessive legitimizations from history, both contextualism and rationalism are preemptive tactics that abort history before it can happen."