In cinema, an object is "diegetic" when it belongs to the world of the story. Star Wars' lightsaber exists in the film's world — not ours. The poster on the protagonist's wall, the bottle on the table, the phone they use: all diegetic elements that build the world without needing explanations.
Julian Bleecker adapted this concept to design fiction with the term "diegetic prototype": an object designed as if it belonged to a future world. It does not need to work — it needs to be credible enough to provoke a conversation. An ID badge for "Class B" citizens. A manual for a home environmental monitoring device. A receipt from a drone delivery service.
The fundamental principle is "show, don't tell". A report on the future of surveillance describes trends, statistics, scenarios. A diegetic badge shows the future: the design, the colours, the information required, the language used. Whoever looks at it immediately understands what kind of world produced it — without reading a word of analysis.
Diegesis works through details. A 2040 instruction manual does not say "in the future privacy no longer exists" — it shows a chapter on how to register your biometric data to access public services. A product catalogue does not say "the circular economy has won" — it shows repairable, modular objects with labels on material provenance.
This approach has an enormous advantage in civic and participatory contexts. When you present a scenario as a report, people become critics of the document — they find errors, challenge the premises, get bored. When you present a diegetic artefact, people become inhabitants of the world: "Would I use this?", "Who has access to this service?", "What happens if I lose the badge?".
Building diegesis requires rigour. Every detail of the artefact — typography, colours, language, materials — must be coherent with the world you are imagining. An incoherence breaks immersion and reduces the artefact to a curiosity instead of a tool for reflection.