A brief history of risk.

Despite increasing life expectancy and high levels of welfare, health care, and public safety in most post-industrial countries, the public discourse often revolves around perceived threats. Terrorism, global pandemics, and environmental catastrophes are just a few of the risks that dominate media coverage. Is this public discourse on risk disconnected from reality? To examine this issue, we analyzed the dynamics of the risk discourse in two natural language text corpora. Specifically, we tracked latent semantic patterns over a period of 150 years to address four questions: First, we examined how the frequency of the word risk has changed over historical time. Is the construct of risk playing an ever-increasing role in the public discourse, as the sociological notion of a 'risk society' suggests? Second, we investigated how the sentiments for the words co-occurring with risk have changed. Are the connotations of risk becoming increasingly ominous? Third, how has the meaning of risk changed relative to close associates such as danger and hazard? Is risk more subject to semantic change? Finally, we decompose the construct of risk into the specific topics with which it has been associated and track those topics over historical time. This brief history of the semantics of risk reveals new and surprising insights-a fourfold increase in frequency, increasingly negative sentiment, a semantic drift toward forecasting and prevention, and a shift away from war toward chronic disease-reflecting the conceptual evolution of risk in the archeological records of public discourse.