Stagnation and Scientific Incentives

New ideas no longer fuel economic growth the way they once did. A popular explanation for stagnation is that good ideas are harder to find, rendering slowdown inevitable. We present a simple model of the lifecycle of scientific ideas that points to changes in scientist incentives as the cause of scientific stagnation. Over the last five decades, citations have become the dominant way to evaluate scientific contributions and scientists. This emphasis on citations in the measurement of scientific productivity shifted scientist rewards and behavior on the margin toward incremental science and away from exploratory projects that are more likely to fail, but which are the fuel for future breakthroughs. As attention given to new ideas decreased, science stagnated. We also explore ways to broaden how scientific productivity is measured and rewarded, involving both academic search engines such as Google Scholar measuring which contributions explore newer ideas and university administrators and funding agencies utilizing these new metrics in research evaluation. We demonstrate empirically that measures of novelty are correlated with but distinct from measures of scientific impact, which suggests that if also novelty metrics were utilized in scientist evaluation, scientists might pursue more innovative, riskier, projects.