Architecture is said to be a science and an art as it is about construction and communication, form and matter, rule and novelty. The paper begins by looking at how architecture has been discussed in the literature from the words of both architects and theoreticians. This leads to identify a set of architecture's core elements, in particular regarding the meaning of rules, and a notion of meta-rule about composition choices in architecture. It follows that the act of creativity has a way to manifest itself into this domain via the described interplay between rules and meta-rules. The main contributions of this paper are an ontology-driven discussion of architecture from the given perspective, and an initial proposal on how to isolate and understand architectural rules. The goal is to show that there is a way to model these elements and their interactions, that is suitable for future integrations into formal systems. This, we believe, can turn architectural creativity into a subject for formal representation and exploitation.
Architecture embraces and integrates several domains: design, civil engineering, material
science, social science, aesthetics etc. making it an inherently interdisciplinary domain
along many others like engineering, economics and medicine, just to name a few. Yet,
architecture is interdisciplinary in a stronger sense as it is, has been and aims to be at
the same time a science and an art [
The creation process in architecture starts with the request of the design of a
building or the (re-)organization of an area, and ends with the implementation of the chosen
solution. Overall it is a complicated process and we focus on the first part only, namely,
the design process. This restriction in focus highlights the goal of the paper, that is, to
characterize two core factors in the architect’s practice: architectural rules and creativity.
Generally speaking, we aim to shed some light on the relationship and integration of
these elements, and on their connection to architectural types, even though we will not
tackle explicitly the latter notion in this paper. Also, we do not deal at this stage with the
larger issue of computational creativity, nor with the problem of designing AI tools for
creativity. The interested reader can look at approaches like [
The design process in architecture is usually divided in subphases starting with the
setting of the project requirements, followed by the generation and selection of the idea
conception, and finally ending with the complete drawing of the design entity. These
steps are usually seen as forming a process that takes place in the cognitive realm of
the architect as well as in physical reality: the acts of imagination determine how to
conceptualize the entity and to draw it, the actual drawing realizes the mental image and
provides an objective perspective which is used by the architect for the subsequent artistic
and/or practical (re-)elaboration in a sort of feedback loop that converges to a solution.
This high level description could apply to any modeling process, for instance those in
industrial design, except for the special implications of the term ‘artistic’. Wittgenstein,
a philosopher and a practitioner of architecture and design, highlights this as follows:
“the image of the world is a practice: it offers different ways of comparing and acting,
so rules are useful and necessary but at the same time they are changed by the practising
and the designing action, as the riverbed moves with the flowing water”. This key feature
of architecture design is highlighted by Pisani [
Structure of the paper: in Sections from 2 to 4 we look at architecture, its domain and how to understand its rules and practice as discussed by the practitioners (architects) and the theoreticians (architects, historians and philosophers). These sections present the words of the practitioners with their evocative, sometimes metaphoric language. Building on observations raised during the analysis of the experts, a novel classification of architectural rules, guided by our ontological analysis, is developed in Section 5. Section 6 concentrates on the notion of meta-rule, that is, rules that guide changes in architecture and open the domain to the manifestation of creativity. Section 7 concludes highlighting potentialities and limitations of this work, and indicates future steps.
Practitioners of a discipline may disagree on methodology and relevance of the results,
but share a common understanding of the discipline itself. This is not so in architecture.
Fisher questioned the understanding of architecture in an attempt to identify its core
nature. “What sort of enterprise is architecture?; does architecture have essential features?;
what kinds of things does architecture make?; is architecture always, only sometimes,
or never an artform?; what distinguishes architecture from other artforms?; and does
architecture include all built structures?” [
One can claim that an object is architectural when it features forms which are proper
to the domain. This means that an object is architectural independently of the community
that judges it. Within this view, often one assumes that forms proper to architecture can
be chosen from a stylistic menu, leaving architects freedom to uphold possible forms
or design answers [
Objects made in architecture have to accomplish the ordinary goals, e.g. satisfy social needs, and to give a sense of beauty and surprise. Via their presence, architectural objects change the sense of space and innovate the modalities for an aesthetic fruition of it. This is obtained by exploring new ideas, which then go through a process of ‘sedimentation’ before their actual exploitation in architectural design. Once sedimented, they return (consciously or else) in the architect’s work as signatures, reminiscences, even phantoms, and strive to find a place. The result of this process, interior to the architect, is found in the interplay among the built entity (its objective properties), the subjective view of the architect (her intention or vision of the created entity), and the community that “experiences” it. We take this interplay to be the real meaning of architecture. The surprise, the wonder raised by the built entity, continues in time primarily in the (perhaps subtle) perception of the harmony of parts and of proportions, in what has been designed to be a flexible space, i.e., a space that interacts, adapts and regenerates with the changes in the community living it and around it.
Over the centuries architects have tried to understand the complexity of their knowledge domain and to systematize, or at least to put some order in, the key elements that are at the core of architecture. This effort led to a clarification of different views and related approaches, and highlighted some regularities.
Architecture is based on a corpus of knowledge and rules. Architectural knowledge
and rules are often discussed as forming a proper theory. Yet, a comprehensive statement
of this theory does not exist. One reason is that architectural theory aims to codify
practical and theoretical knowledge. Something similar, although at a simplified level,
happens in engineering where design theory splits in a number of sub-phases, each
requiring specific theoretical and practical expertise. The interesting point is that the engineer
is thought of as a neutral player in the design process, a figure in the background. The
architect instead is in the foreground, her presence is felt in any attempt to understand
what is going on during the architectural process and so is when one tries to understand
architecture itself. Any prescriptive, even didactic, expression manifests the architect’s
intentionality to promote a given or new way to do architecture, and to ground her
architectural practice in moral, social, psychological, or theoretical bases [
Producing is primarily a physical act; composing is primarily an act of the mind.
Architectural objects are the outcome of composing and producing in a context that mixes
art and science. This happens in artistic disciplines where the generation of internal rules,
grammars and techniques, leads to results that go beyond the simple concretization of
insights. Creativity can very well be thought of as a rational activity [
According to Schon [
Analogy, re-combination and re-elaboration are continuously applied to the design
due to the input of different stimuli, including the personal memories of the architect
[
The rules we aim to study are not related to the interaction among natural laws,
material and civil engineering (e.g. requirements to ensure a dwelling’s stability), they are
essentially architectural in the sense of being the architect’s choice to create an object
(or space) of architecture. An architectural rule about compositional choices is not just a
constraint expressed once for all in some, formal or natural, language. Following these
architectural rules does not mean to apply them at face value since the same rule can
find its place at different architectural levels. The term ‘architectural grammar’ indicates
a corpus of rules which is both a summary of the knowledge of architectural elements
and of the rules for an appropriate use of these elements according to the task to
accomplish [
Both the corpus and the meaning of the architectural grammar that the architect embodies, change over time under the pressure of memory and of the instances of architectural design that the architect accumulates sketching possible solutions. The meaning of a rule about composition choices for an architect is what is learned when the rule is incorporated into her thinking and is modified into her acting. In this setting the understanding of the interaction between the concepts of rule and of meaning is challenging and is an issue that we do not investigate here as it is rooted in the view of architecture as an art, and of the architect as a cognitive agent.
The architectural rules that constrain composition choices are not rules about reality
nor about the laws that govern reality. For this reason, these rules do not need to bend to
reality or to coherence. They are, logically and ontologically speaking, arbitrary,
contingent to the state of the discipline and bound to be violated. Rules’ arbitrariness is here
essential: in architects’ words they determine the meaning without being the subject of
any specific meaning [
Our approach relies on the use of ontological methodologies to detach the analysis of architectural rules from the traditional viewpoint. Taking a fresh look at these rules, we reach a novel proposal for the classification of architectural rules. More precisely, we are not interested in classifications based on historical development, economic considerations or engineering functionalities. This means that we are not after rules as typically expressed in an architectural textbook. Instead, we look at the very elements a rule regulates to get the gist of its message.
Our assumption is that even though the architect may interpret a rule in different ways, the type of entities to which the rule applies should not change. If these change, we take it to be a different rule. Based on this, we also make the assumption that complex architectural rules can be restated in terms of combinations of rules falling into our classification. This latter assumption is actually justified by the adoption of a foundational ontology. Here we do not investigate this issue further.2
2The claim is also supported by the practical experience as architect of one of the authors. However, note that there is a large variety of architectural rules across history and it is hard to make a definitive statement on this issue. Also, the topic is further complicated because some rules are primarily practice-based and only informally presented.
Framing rules. Since architecture pivots around the construction of a physical object or the organization of a physical space by adding / modifying objects in it, a class of rules frames the objects as a whole, the understanding of the design space and the aggregation of surfaces and features. These are general rules, like the golden rule, that guide the tension between the parts of the object(s) and their place in the physical space, they help to find the point of reciprocal equilibrium towards the attainment of a global internal and external harmony. Ontologically these rules focus on regularities among shape and size of physical objects (and/or their parts) possibly including the position of these objects in space. We call these framing rules.
Quality rules. A dwelling is a complex system with many features: from the height to
the extension, from the color to the texture of the material. A second class of rules
constrain other qualities of the physical object to be. They control the regularity of the
dimensions of surfaces and volumes, the coordination of flowing / broken spaces and, more
generally, a coherence in the ‘narrative’ of the object and its space. The quality can be
decided apriori and calculated to ensure, e.g., environmental control of the space
(temperature, acoustics, dispersions), aesthetics which is primarily about the lines that close
the spaces (curve, straight) and texture that animates surfaces, quantity of transparencies
or openings. Ontologically these rules focus on relationships across qualities in order to
ensure a determined perception of the environment. We call these quality rules.
System rules. Since the architectural object is a system, some rules guide the interaction
and disposition of its parts including the relationship between surfaces, volumes, their
reciprocal articulation, and the overall impact of the entity as a whole. For instance, areas
dedicated to technical installations should naturally encompass the interactions across
the space and system they serve. Ontologically these rules look at the object as a whole
formed by a network of interacting components. These are called system rules.
Location rules. The architectural object is mainly an object in a place so that it is never
thought in isolation. The idea of how the building will look like in its environment guides
the design from the beginning and the result is strictly tailored to that specific physical
place. Some rules determine the harmony an architecture should create with respect to its
environment [
Perception rules. The architectural object is not only a physical object but a place that is seen and recognized. This aspect is the focus of the rules that control how the object should be perceived given its position and design. While rules of proportions are idealized, here we find rules about perceived proportions (perceived with the eyes, with the ears, with the touch) that help to control the observer’s sense of balance. These rules can make an object look lighter, give the feeling that the building aligns with the surrounding environment, or suggest an affordance for that building. Ontologically, these are rules that guide how an observer should perceive the object (and the space around it) depending on her location. We call these perception rules.
Function rules. As the design object has also functional purposes (house, hospital, bridge, factory etc.) and social relevance (a town hall is a symbol of ruling and control, a hospital of caring, a square of freedom and meeting), two further rule classes are
Topic of the rules Example the tension across the parts, harmony Golden rule, the Modulor scale the physical and aesthetic qualities of buildings Color, open/close space harmony the relationship and interactions across parts Usability, integration metrics the integration of building and environment Ecological harmony the perception of the building and its environment Wellbeing metrics the purpose of the building Airport layout the social role of the building Town hall symbolism the use and personalization of the building Open form rule, social exploitability
Table 1. Ontology-driven classes of architectural rules. distinguished: function rules and society rules. Function is about the specialization of a space as suitable to perform some types of activity and is controlled by what we call function rules. Ontologically, these rules help to indicate and control possible uses of and interactions with the object.
Society rules. There are rules aimed to give the object an appearance that matches its symbolic significance. They apply also to iconic landmarks (Tour Eiffel, Statue of Liberty) and, generally speaking, depend on the cultural and social organization of a population. Ontologically, these rules are about the role the object is supposed to play in the social and cultural system. We call these society rules.
Living rules. Finally, since the design object is a place for living or an entity to live with, let it be a house, a square or a city gate, another set of rules are devoted to the organization of the living and the practices for interacting with the object. Ontologically these rules control the development of social practices and aim to guide how and to what extent the community can transform/adapt the object. We call these living rules.
As architecture is an evolving domain that continuously influences and is influenced by culture and society, the number of rules that we find in these classes keeps extending. In textbooks these rules are often intermixed with other aspects (from material properties and construction techniques to engineering constraints or even legal regulations) or are collected in families that identify practices, cultures, styles and regulatory systems. Most of these groups are studied for their historical relevance so that we know about their introduction, meaning, motivations and, eventually, superseding. The artistic and scientific literature on architecture has developed comparisons of rules mostly within these special clusters. Exceptions are primarily due to technical comparisons and have rarely highlighted the possibility to develop a space of architectural rules as presented in this paper. Our analysis sets the basis for the recognition and identification of such space, and can lead to its systematic investigation via formal ontology and, subsequently, knowledge representation methodologies.
An architectural object satisfies a set of rules which are distributed across most, if not all, the eight classes identified in the previous section. Many of these rules are selected because of the initial requirements, the environment in which the object is placed (type of land, urban context), the architectural style of reference and the cultural-social period. Not all these rules need to be explicitly considered at design time. Others are consequences of the combination of the explicitly chosen rules since many of these deals with intertwined architectural aspects like, e.g., spatial, material and structural rules. The architect applies several strategies to overcome the problem of rule interactions and these strategies require the introduction of meta-rules. In case of conflicts, the architect tries to change or reinterpret the rule, for example by applying the rule to a limited subclass of situations thus weakening its applicability. We can show this by comparing architectural rules with standard logical rules.
In classical logic from a rule of form “A implies C”, it follows that “A and B imply
C” (logically speaking, this is the rule of weakening on the left). This result is not always
true in architecture. Assume that we have a rule: “if X is a cornerstone not directly
supported by a wall, then X itself is directly supported by a column” which was accepted
up to the middle of the 20th century. As seen above, in classical logic this rule implies
the following: “if X is a cornerstone not directly supported by a wall and the weight
it supports is distributed to other columns or walls, then X itself is directly supported
by a column.” The latter rule, not being enforced by physical laws, is an architectural
rule3 and can be accepted or rejected by the architect (Fig. 1). Actually, the Modern
Movement [
Similarly, the architect can modify a rule by questioning the broadening of its consequences (in classical lingo, weakening on the right). Take a traditional rule with logical form “A0 implies B0”: “if the city gate is closed, then it is not possible to enter / exit the city.” Compare this to a modern rule, due to a change of use and status of the city door, with form “A0 implies C0”: “if the city gate is closed, then one can still move all around the gate.” (Fig. 2). These two rules can be combined into the rule “A0 implies B0 or C0”: “if the city gate is closed, then it is not possible to enter / exit the city, or one can still move all around the gate” which is logically sound but architecturally pointless. The reason is that statements B0 and C0 carry different architectural understandings (background assumptions) which are not just different, they are incompatible. Indeed, if a rule is not capable to provide a sense of guidance and prescription (as the rules we started with), it is useless to the architect.
Our analysis of the history of creativity in architecture leads us to identify several types of architectural meta-rules: strengthen/weaken the initial conditions for the application of the rule strengthen/weaken the consequences of the application of the rule 3This rule became an architectural choice because of technology evolution. Yet, only a couple of centuries after the technology was made available we started having designs where the rule was broken. This shows that the mere possibility of breaking an architectural rule does not suffice, we still need an architect’s act of creativity to do it.
divide the rule in subcases with different conditions/consequences (specialization of the rule context) maintain a rule only apparently (i.e., maintain the perception of the rule)4 apply some of the rules at a different level of granularity (including using a rule as a meta-rule) substitute a rule with a new one (e.g. when new technologies allow for innovative solutions)
These types do not cover all the aspects related to different ways to elaborate the corpus which can be the result of a mix of different reasoning types like abduction, deduction, and induction. Finally, we do not tackle here how the architects make the choice of which of these rule types to use and the motivations for it, after all this is where the architect exercises her creativity and our focus in this paper is limited to the space of architectural rules and meta-rules.
4“Because architecture aims to please the sense, and if the sense is deceived, as frequently happens, into
judging a straight object to be crooked, a horizontal one to be inclined, and a large one to be small, additions
and compensations must be made in order to satisfy and oblige it and supply what it mistakenly sees lacking.”
[
An architectural grammar is a summary of the domain knowledge comprising
architectural elements and the rules for their appropriate use to accomplish a task [
After discussing these difficulties, we have proposed a classification of architectural rules which, based on ontological analysis, objectifies and disconnects them from the usual contextual reading. In this way the relationships (and their interdependencies) among the rules can be identified and studied in a context-independent manner. When applied in a project, the rule is again contextualized, a process that introduces new dependencies related to the context. Having started from the objective classification, it is now easier to understand the source(s) of the conflict between rules, and to coherently choose a suitable strategy to overcome it.
This paper has presented an initial framework to rethink architecture as a discipline
of rules and meta-rules which can make it suitable to formal analysis and exploitation,
and has practically showed how creativity can find its place in a scientific domain like
that of rule-based systems. In the future we plan to consolidate and validate the proposed
rule classification. As mentioned in the introduction, we are also working on a general
notion of architectural type which would make possible to integrate architectural types,
architectural rules and meta-rules in a unified view. The framework we envision could
eventually lead to a radical change in the way architecture is taught, and could guide
the integration of CAD systems with AI methodologies to support creative thinking as
discussed, for instance, in [