For certain situations, applying either bottom-up design or traditional top-down design is more efficient. Traditional top-down design gives consistent, predictable results, whereas bottom-up design gives unexpected, more novel configurations. The price for novelty and greater freedom is a larger number of steps, and consequently more time invested in the project.
An essay on p2p design and architecture, by our friend Nikos Salingaros.
Abstract:
“The two methods of adaptive top-down and bottom-up design are shown to be theoretically equivalent. Even though they differ drastically in their application, each one can help the other, and they may even be combined in a particular project. Both cases rely on traditional solutions encoded into the built environment, which represents the product of our collective intelligence. Implementing this realization to rebuild our world can lead to an unprecedented degree of support for human life from architectural and urban structures.”
Excerpt:
” I wish to clear up an old problem that has prevented the useful collaboration between two distinct schools of thought about design. There exists a group of architects and urban designers who follow what can loosely be termed “Classical” rules. These impose forms which have been thought out entirely during the planning stage. Practitioners include formal Classical architects, Neoclassicists, and New Urbanists, who tend to apply typologies derived from Greco-Roman and Nineteenth Century models. Their results are comfortable, ordered, human-scaled, and figure prominently in the large-scale architectural and urban regeneration of our cities.
The other school of design (characterized as “Structural” by Brian Hanson and Samir Younés) abandons already developed geometrical typologies and instead evolves solutions afresh in each instance. Practitioners here try to evolve the design in real time, often with the explicit and ongoing collaboration of potential users. The design — and building — process is bottom-up rather than top-down. Since a main point of the method is the continuing influence of users to change form as it is being built, the design can evolve into an unexpected final state, much like our result from computer evolution mentioned above. A key tool of this design school is the use of Alexander et. al.’s “A Pattern Language”. Those patterns are evolved solutions for accommodating human uses and needs: they are connective and configurational prescriptions rather than geometrical constraints.
At first glance, there would appear to be little in common between these two design approaches, yet both rely on a Darwinian process of selection. The difference is as follows.
In the top-down design process, an intentional Darwinian selection occurs in two parts:
(i) in the past, when the geometrical prototypes comprising the form language were evolved to adapt to human use and sensibilities;
(ii) in virtual space in the mind of the designer before any construction takes place.
The top-down instance uses a proven repository of forms. It is more efficient to concentrate the secondary selection within one mind, so the design tends to be less collaborative and more the result of the decisions of a single person.
In the bottom-up design process, we have a very similar division into two parts:
(i) a Darwinian process has in the past generated Alexandrine patterns;
(ii) Darwinian selection takes place further in real time during preliminary trials and actual building.
The bottom-up instance, where a number of persons have significant input into the form as it is evolving, has opposite characteristics from the top-down process. Because of their fundamentally different approaches, top-down design relies more on geometry and an inherited form language, whereas the bottom-up approach dispenses with geometrical prototypes and instead works within the design constraints represented by “patterns”.
The top-down design that I am proposing consists exclusively of traditional and classical prototypes, which have themselves evolved over time through Darwinian selection. A danger with top-down design is that it could employ prototypes that have never evolved, and are thus not adaptive to human needs. Also, it is possible to put together perfectly adapted prototypes in a non-adaptive manner, unless one is very sensitive to the local forces. This problem is best handled by employing some of the techniques from bottom-up design, which allows self-organization as discussed later in this paper.
Bottom-up design has a much better chance for adaptation, but the opposite potential weakness: unless it is intentional, and selection is governed by adaptation to human needs, it becomes random. Disorganized growth, however, is parasitic to healthy architectural form and urban fabric, as it is to biological tissue. Such growth is neither adaptive, nor the result of self-organization. It represents the proliferation of structure that does not relate to the whole. Evolved form generates organized complexity, whereas random growth generates disorganized complexity. Organizational principles are in general so complex that they are best helped by evolved solutions, which brings us back to a reliance on top-down methods of organization (though emphatically not the imposition of forms).
For many decades, people have assumed that top-down and bottom-up design methods represent opposite and mutually contradictory approaches. One can trace the famous (and very regrettable) argument between Lewis Mumford and Jane Jacobs to precisely this difference. I, together with other authors such as Hanson and Younés, do not believe the difference to be one of substance, but merely one of application. Yes, the actual hands-on design will follow a different path in either of the two practices, yet the two processes rely on a basically similar mathematical structure, hence on each other. Both design methods can lead to optimal results that are adapted to human functions and sensibilities.
For certain situations, applying either bottom-up design or traditional top-down design is more efficient. Traditional top-down design gives consistent, predictable results, whereas bottom-up design gives unexpected, more novel configurations. The price for novelty and greater freedom is a larger number of steps, and consequently more time invested in the project. The possibility of combining bottom-up design with traditional top-down design has already been proposed by Hanson and Younés (in what they call the “Third Way”). There is essentially one adaptive design process, and different practitioners may choose to carry out its steps either in a virtual environment (i.e. inside their heads), or in the real world. In the latter case, it is possible to involve more people in the selection process, so that the design becomes “participatory”.”
On Design and Collective Intelligence:
” Despite the distinction between top-down and bottom-up design implementations, both represent an application of collective intelligence, but in very different ways. The selection process that generates a design solution via bottom-up methods is the result of actions and decisions by a host of individual inputs. A collective design project includes selection by the architect (or a group of architects), end-users, and environmental forces. All those forces are perceived and inputted into the selection process by human agents acting as a collective intelligence. Such forces may or may not be perceivable by the individual designer in a bottom-up process, because of their number and complexity.
Adaptive top-down implementation also uses collective intelligence. The built environment is a common repository of stored information. Developments having to do with forms and structures that are adaptive to human physical, sensory, and psychological needs are stored in pre-modernist built structures. This information represents the work of an enormous number of individuals, as well as collective efforts throughout the ages. It has the advantage of being accessible to everyone. Unlike information stored in books, which until relatively recently was accessible only to an educated class, information stored in built form is immediately accessible, and acts as a working memory for society.
The storage capacity of such a collective memory is far larger than the memory capacity of any individual human being. Top-down design is helped by using encoded information from traditional typologies — these broaden the intelligence of the individual designer or group of collective designers. A top-down design implementation that utilizes traditional typologies therefore extends human intelligence into the built environment, by incorporating the experience of other people from the past. On the other hand, the deliberate destruction of the traditional built environment, which was perpetrated by the modernists, erased society’s collective memory. This act reduced society’s collective intelligence, and severely limited its ability to solve architectural and urban problems.
The built environment is the medium in which adaptive design solutions have evolved (and are still evolving). Exploration of innovative designs relies on selection and checking against adaptive examples stored in the collective (built) memory. Adaptive designs enhance human life; they are an inseparable part of humanity’s healthy functioning. Designs that damage this life represent pathologies, which would normally be rejected when recognized as such. A particular group of people (incredibly, the professionals in those disciplines) have been promoting a pathological type of structure both on the architectural and urban scales. As human intelligence no longer extends to the built environment, it cannot protect us against architectural and urban pathologies, which therefore proliferate.“
From the conclusion:
Architecture needs to be based on a scientific understanding of adaptive design principles. I described Darwinian processes and their role in design, using the evolution of a computer program (a number-sorting algorithm) to make a point. Evolved solutions acquire a complexity that often exceeds the intelligence of an individual human being. For this reason, the traditional built environment is a product of a collective intelligence (such as shown by social insects) applied to deepen the human understanding of form. Adaptive top-down and bottom-up design methods were explained with reference to results from complexity theory. An old misunderstanding, which considered top-down and bottom-up methods to be mutually contradictory, was cleared up — in fact, as long as they are truly adaptive, the two methods are mathematically equivalent.
I also criticized the arbitrariness of non-adaptive design methods in widespread use for the past several decades. Architects who replaced historic solutions adapted to human needs with simplistic image-driven typologies revealed a total lack of understanding for the role of design. They also introduced an arrogance into the profession, which, combined with those non-adaptive design methods, has made the built environment more and more dysfunctional and even inhuman. It appears that despite repeated and well-publicized calls for design according to adaptive principles, these tendencies of contemporary architecture and urbanism show no signs of abating. I believe that it is time to rebuild a functional environment that better supports human life. This paper suggested a basis for doing so.”