The way a building is designed is not a value-free choice. Architecture is not neutral. All buildings have a philosophy that underpins them. Most cities in the world today include 'hostile architecture' - buildings designed to exclude certain behaviours and marginalised people, such as spikes outside shops to prevent rough sleeping. Rather than fostering freedom and community, modern buildings prioritise control and surveillance. Karl Mendelson here argues urban design should be for all individuals and promote participation in society, not simply serve the interests of property owners or the powerful.

Walk through any major city, and you’ll see them: benches with armrests dividing every seat, spikes lining storefronts, sloped ledges that look like places to rest—until you try. Architecture has long shaped the way we experience the world around us. Public spaces throughout our recent history served as venues for meetings, leisure, and rest. Yet, in recent years, the favoured fashions of urban designers have sought to limit, rather than encourage, the uses of these spaces.

This is where hostile architecture comes in: a design philosophy that explicitly seeks to restrict certain behaviours, from sleeping to skateboarding, through uncomfortable or impractical features. While this might seem like a pragmatic way to manage public space, it hides a deeper ethical issue. Hostile architecture isn’t just bad design; it’s a philosophical approach that values control and exclusion over community and inclusivity. When we design spaces to prevent certain people from using them, what message does that send about who belongs in the city?

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This shift in design philosophy represents a broader political change, one that has moved from openness and engagement to control and exclusion. Philosophers like Hannah Arendt, Michel Foucault, and David Harvey provide us with a lens through which to critically examine this shift and the deeper ethical implications of hostile architecture. Public spaces should be for everyone, but hostile architecture rewrites that rule. As we examine the consequences of these design choices, we need to ask: What kind of cities do we want to live in? Are we shaping them for control or for the community?

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These designs are not neutral; they are choices about who belongs in the city and who is not.

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One of the most troubling aspects of defensive design – the more acceptable face of hostile architecture - is its lack of formal acknowledgement by the very individuals and firms who implement it. Many architects, urban planners, and property developers who incorporate hostile or exclusionary design elements into public spaces rarely, if ever, make a clear, public commitment to these practices. Instead, these decisions are often framed in terms of efficiency, order, or security—virtues that, on the surface, seem entirely neutral and uncontroversial. The use of hostile features is rarely justified as a moral choice; rather, they are typically rationalised as necessary for managing behaviour and maintaining public safety. This lack of transparent intention surrounding defensive design allows it to be implemented without the scrutiny it deserves, leaving little room for public debate about the ethical ramifications of such choices.