In 1962, a researcher studying Iowa corn farmers arrived at a framework that explains how ideas, technologies, and behaviours spread through societies. Sixty years later, Everett Rogers's model is everywhere — and his most important warnings are still being ignored.

It starts with corn. In the early 1940s, two researchers studying agricultural practices in Iowa noticed something that seemed, at first, like a simple question of timing: why did some farmers adopt hybrid seed corn quickly, while others waited years, and some never adopted it at all? The answer, it turned out, was not primarily economic or technical. It was social. Adoption moved through networks, following patterns that had more to do with trust, identity, and the structure of communities than with the objective merits of the innovation itself. The farmers who adopted early were connected differently — to information sources, to each other, to the idea of themselves as people who tried new things. The ones who came later were waiting to see what happened to the ones who went first.

Everett Rogers spent the next four decades discovering that this pattern repeated everywhere. In public health campaigns and educational reform, in the spread of technology and the adoption of new cultural practices, the same basic dynamics kept appearing. Diffusion of Innovations, first published in 1962 and revised through five editions, is his attempt to synthesise those observations into a general theory of how new ideas move through societies.

The framework he developed is now so widely used that it has almost disappeared into common sense. The five adopter categories — innovators, early adopters, early majority, late majority, laggards — have become standard vocabulary in marketing, product development, and organisational change. The S-curve of adoption, moving slowly at first, accelerating through the middle, flattening as saturation approaches, appears in business presentations everywhere. Rogers has been so thoroughly absorbed that it is easy to forget how much analytical work the framework actually does — and how much of it gets lost when the typology is lifted out of context and used as a simple segmentation tool.

What gets lost, most importantly, is Rogers's insistence on time. Adoption is not a moment — a decision made once, cleanly, with permanent effect. It is a process, moving through stages: awareness, persuasion, decision, implementation, and finally confirmation or discontinuance. That last word is significant. People abandon innovations. They adopt them, find them wanting, and stop. Or they adopt them, discover unintended consequences, and wish they hadn't. Rogers takes this seriously in a way that most applications of his framework do not.

His most valuable and least-cited contribution is the critique of what he calls the pro-innovation bias — the assumption, so deeply embedded in how we think about new ideas that it barely registers as an assumption, that adoption is inherently good and non-adoption is a problem to be solved. Rogers challenges this directly. Not all innovations are beneficial. Not all diffusion serves the communities through which it spreads. Change agents — the researchers, consultants, marketers, and policy makers who work to accelerate adoption — frequently proceed on the assumption that the innovation's value is self-evident, and that the task is simply to overcome resistance. Rogers argues that this framing is not just intellectually lazy but potentially harmful: it systematically underweights the possibility that the people who aren't adopting might have reasons worth understanding.

His proposed corrective — integrating foresight research and scenario planning into diffusion studies, building consequence assessment into the process rather than conducting it retrospectively — remains, decades later, more aspiration than standard practice. We are still better at spreading innovations than at evaluating them.

James Burke, whose lecture series and books have spent decades tracing the unexpected paths through which ideas connect and transform across history, arrives at a complementary unease from a different direction. Where Rogers maps the social mechanics of how innovations spread, Burke is fascinated by the near-impossibility of predicting where they will lead. His argument — developed through the television series Connections and its successors — is that the consequences of any significant innovation are almost always invisible at the point of adoption, because they depend on collisions with other ideas and circumstances that don't yet exist. The printing press did not obviously imply the Reformation. The stirrup did not obviously imply feudalism. The transistor did not obviously imply the smartphone. Burke's history of technology is a long demonstration of Rogers's warning: that the pro-innovation bias is not just a methodological error but a failure of imagination about how deeply a new idea can reshape the world it enters.

Together, Rogers and Burke form a picture of innovation that is considerably more demanding than the one that tends to circulate. Adoption is not progress. Spread is not endorsement. The question is not only whether an idea moves through a society, but what it does when it gets there, and whether anyone was paying close enough attention to find out.