Preface

In the spring of 2020, while a pandemic swept the globe, something else spread alongside it: a torrent of false claims, manipulated videos, miracle cures, and conspiracy theories so overwhelming that the World Health Organization coined a new word for it — "infodemic." People shared posts claiming that drinking bleach could prevent COVID-19. Governments that had initially underreacted pivoted to over-react based on models that hadn't been peer-reviewed. Anti-vaccine communities that had spent years building audiences on YouTube found their moment. Facebook groups promoting 5G tower arson grew from hundreds to hundreds of thousands of members in weeks. The virus spread through bodies; misinformation spread through minds. Both were killing people.

But the infodemic of 2020 was not, as some commentators claimed, something new. It was the culmination of decades of structural change in the way humans produce, distribute, and consume information — changes that this book traces from the ancient world to the algorithmic present. The printing press created both the Reformation and some of the most vicious propaganda Europe had ever seen. Radio gave us FDR's fireside chats and Father Coughlin's antisemitic broadcasts. Television brought the civil rights movement into American living rooms — and it brought the Gulf of Tonkin Resolution based on an incident that largely did not happen. Every communication revolution has simultaneously democratized information and created new vectors for manipulation.

What makes the digital age different is not that misinformation exists. It is that for the first time in history, individuals with modest resources can reach millions of people with unverified claims, algorithms optimized for engagement rather than accuracy amplify the most emotionally arousing content regardless of its truth, and artificial intelligence can generate convincing false text, images, audio, and video at scale and near-zero cost. The structural conditions for an epistemic crisis have been quietly assembled over thirty years. We are now living in that crisis.

This textbook was written because the problem demands a comprehensive response — and most responses have been inadequate. Checklist-based media literacy curricula ("CRAAP test") were designed for library databases, not for the open web of 2024. Fact-checking organizations do essential work but cannot scale to the volume of misinformation they face. Platform content moderation is caught between the imperatives of engagement and the requirements of accuracy. Political polarization makes consensus on what counts as misinformation nearly impossible to achieve.

What is needed — and what this book attempts to provide — is a deep, integrated understanding of the problem from multiple angles simultaneously: the philosophy of truth and knowledge; the cognitive and social psychology of belief; the history of propaganda and misinformation; the political economy of information platforms; the computational methods for detection; the evidence base for interventions; and the ethical framework for thinking about our responsibilities to each other as members of a shared epistemic community.

This book is deliberately non-partisan. The problem of misinformation does not belong to one political side. Research shows misinformation is produced and consumed across the political spectrum, though its specific forms and targets vary. Our goal is not to tell you what to believe about any specific political question, but to equip you with the tools to evaluate evidence well — wherever it comes from, wherever it leads.

Each chapter builds on those that precede it. Part I gives you the philosophical and psychological foundations for understanding why misinformation is such a persistent human challenge. Part II maps the modern information ecosystem that enables its spread. Parts III and IV catalog the types of misinformation and the methods for detecting them. Part V develops the critical thinking and media literacy skills that constitute your personal defensive armor. Parts VI and VII examine the political dimensions and the landscape of countermeasures and solutions. Part VIII pushes into the frontier questions — generative AI, global perspectives, and the ethics of truth.

By the time you finish this book, you should be able to identify a propaganda technique in a political ad, run a basic NLP classifier on a news dataset, evaluate the evidence quality of a health claim, apply inoculation theory to design a media literacy intervention, and articulate a principled position on the ethics of platform content moderation. More importantly, you should have developed a set of epistemic habits — habits of curiosity, humility, verification, and charitable interpretation — that will serve you far beyond any specific claim or technique.

The world needs people who can think clearly in conditions of uncertainty, who can distinguish what they know from what they believe, who can change their minds when the evidence warrants it, and who can communicate about complex and contested questions with honesty and precision. We wrote this book for those people — and for the people who want to become them.

The Authors 2024