Indexical architecture

The idea of evidence is obviously important in a juridical context. Evidence comes to the fore when architects deal with compliance (codes and regulations), and get caught up in legal matters, such as contract disputes, liability and compensation claims, and as witnesses.

Evidence is also important in any kind of research context, as in the case of drawing on evidence to support a hypothesis, or to support a judgement, or any interpretation.

Ex post-facto design

Then there’s the more radical idea that to design a building is to manufacture something about which evidence can be derived. A building or component design is an object from which critics, evaluators and users might derive evidence. By this reading, this pre-determined evidence constitutes a propositional statement, a proposal, a goal, an aim, a programme or a brief. The designed object is created ex pos-facto to fit the evidence.

The act of designing has been usefully defined as an abductive process leading from some putative evidence (e.g. qualities and desirable characteristics) backwards to the object that would provide that evidence. It is as if the architect is constructing a crime scene in reverse, about which others have already picked up evidence (signs) and made observations and judgements. That is a Peircean way of viewing design. See post: Shadow of a doubt.

I think I have managed in my own mind to link the role of evidence to C.S. Peirce’s concept of abductive inference, and hence the indexical sign. See previous post: On being a detective.

Descriptionless architecture

Within Peirce’s sign classification system, it’s pretty clear what icon architecture is like, and symbolic architecture. But what is indexical architecture? An indexical sign has the characteristic that it emanates from its object, as if caused by it. See post: index fever. It is a direct relationship requiring no mediating concept, i.e. none of the entailments of a resemblance (icon) or convention (symbol). It is worth repeating one of Peirce’s characterisations of the index.

“The index asserts nothing; it only says ‘There!’ It takes hold of our eyes, as it were, and forcibly directs them to a particular object, and there it stops. Demonstrative and relative pronouns are nearly pure indices, because they denote things without describing them; so are the letters on a geometrical diagram, and the subscript numbers which in algebra distinguish one value from another without saying what those values are” (226).

An index is a cognitively vacuous sign — perhaps a dumb sign, like a pointing finger. I’ve so far encountered four approaches to architecture that are candidates for the idea of an indexical architecture.

1. Functionalism

An indexical architecture depends less on being “expressive,” as either the purveyor (as sign) or object of rich descriptive narrative, i.e. an architecture suffused with ornamentation — of colourful adverbs and adjectives. An indexical architecture speaks to functionalism.

An interesting article by Claire Zimmerman demonstrates how the history of architectural modernism presents variations on the concept of the index, particularly in relation to the indexical character of photography. Similar to the truth claims of a photograph, a functionalist building attempts to demonstrate truthfully what it is.

“We might call a building ‘demonstrative’ if it shows us its own construction (in process and in final result), how it is to be occupied, and how it may have created meaning for its users. ‘Indexical’ implies something else in addition, by suggesting that there may be truth value to the demonstration – akin to the ‘truth’ established by a footprint or a thumbprint as evidence of the prior presence of a foot or a thumb” (277).

In discussing James Stirling’s Leicester Engineering Building, she suggests:

“The building is also indexical in a more literally photographic sense; its architects have anticipated the photographic representation of the building, and have made the school maximally comprehensible – legible, one might say – in images. It is explicit about its own manufacture” (279).

She draws on Peirce for her definition of the index. In summary, “Architectural indexicality can be located as an idea in nineteenth-century structural rationalism and discourses around twentieth-century functionalism” (277).

2. Participatory design

In an article appropriately titled “An indexical approach to architecture”, Anne Bordeleau writes, “The fact that the index is embedded in the very materiality of the world makes it particularly appealing to the consideration of architecture” (86). This leads her to think of an engaged, participatory architecture.

She adds, “to approach architecture indexically is to root comprehension in participation” (88). By this reading, an indexical architecture is an architecture of participation rather than expression. It is also an architecture of direct visceral response.

3. Responsive architecture

Contrary to such a human-centred approach, I think of architecture that deploys sensing devices and actuators to control the environment in response to the changing conditions of the occupants, the weather, etc, as also indexical, where algorithms and code have a part to play in the configuration of surface and space. The photosensitive panels in a building facade that go into shade mode as an indexical sign that the sun is bright, fits the idea of a so-called responsive architecture. See post: Sentient spaces.

4. Forensic architecture

A further response to the challenge of an indexical architecture comes under the heading of “forensic architecture” as developed by Eyal Weizman and his team. They bring an architectural sensibility to the gathering of evidence in support of cases that have a spatial dimension.

Weizman begins his book Forensic Architecture with an account of a court trial that involved the minute examination of an Auschwitz death chamber.

“My aim here is not to reopen the case, but to show how it turned on the condition of the threshold of detectability. It also demonstrates the ongoing tension between testimony and evidence – material and linguistic practices, subject and object and the complex interdependencies between violence and the negation of evidence that are central to the field of forensic architecture. I also begin this book with the Irving trial because it serves as a warning: an independent forensics analyst chaIlenging officially sanctioned truths with the typically limited means afforded to activists is not a guarantee of progressive politics” (20).

The Forensic Architecture web site is rich with projects and examples, and their work is a nominated entry for the 2018 Turner Prize. So far I have not encountered mention of Peirce or indexicality in their discourse, but the theme of evidence looms large. I am particularly taken with an account of their exhibitions.

They see their work as “a form of investigative practice that traverses architectural, journalistic, legal and political fields, and moves from theoretical examination to practical application.” Digital and sensing technologies have a major role in their investigations.

This is not pure detective work however, but an ethos that seems to imbue their work. They accompanied an exhibition at the ICA with the following rationale:

“The work of Forensic Architecture has responded to the widespread increase in availability of digital recording equipment, satellite imaging and remote sensing technology, alongside platforms for data sharing. While such developments have contributed to the complexity of forms of conflict and control, they have also enabled new means of monitoring. Grounded in the use of architecture as an ‘analytic device’, Forensic Architecture’s investigations employ spatial and material analysis, mapping and reconstruction, and extend outwards to overlay elements of witness testimony and the cumulative forms of visual documentation enabled by contemporary media.”

Indexicality (under the guise of evidence) becomes a focus of architectural practice. It also informs an approach to design and presentation: an inaesthetic, evidential approach to architecture: the thing speaks for itself — res ipsa loquitur.


  • Bordeleau, Anne. 2008. An indexical approach to architecture. Footprint: Delft Architectural Theory Journal 3, 79-96.
  • Peirce, Charles Sanders. 1992. On the algebra of logic: A contribution to the philosophy of notation (1886). In Nathan Houser, and Christine Kloesel (eds.), The Essential Peirce, Selected Philosophical Writings Volume 1 (1867-1893): 225-228. Bloomington, IN: Indiana University Press.
  • Weizman, Eyal. 2017. Forensic Architecture: Violence at the Threshold of Detectability. Brooklyn, NY: Zone Books
  • Zimmerman, Claire. 2012. Photography into Building in Post-war Architecture: The Smithsons and James Stirling. Association of Art Historians, (35) 2, 270-287.


  • I am grateful to Asad Khan for introducing me to the work of Forensic Architecture. Asad is currently exhibiting at the Talbot Rice Gallery:
  • The first picture is of the London model at the City Centre in London.  The second is of Google image search results for “forensic satellite imagery” today.

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