Explore the complex interplay between uncertainty, financial markets, and economic policy in this thought-provoking lecture by Prof. Lars Hansen at the Alan Turing Institute. Delve into advanced methods for conceptualizing and quantifying uncertainty in economic analyses, drawing insights from decision theory. Examine two illustrative economies with limited understanding of long-term growth, investigating uncertainty's impact on financial market fluctuations and climate change policy design. Gain a deeper understanding of how incorporating uncertainty into economic models enhances our comprehension of financial markets and informs prudent policy-making. Learn about the differences between uncertainty quantification in economics and other sciences, considering both external observer and internal model perspectives. Discover the connections between this work and the seminal publications of Frank Knight and John Maynard Keynes on risk, uncertainty, and probability.