This is the first book to investigate individual’s pessimistic and optimistic prospects for the future and their economic consequences based on sound mathematical foundations. The book focuses on fundamental uncertainty called Knightian uncertainty, where the probability distribution governing uncertainty is unknown, and it provides the reader with methods to formulate how pessimism and optimism act in an economy in a strict and unified way. After presenting decision-theoretic foundations for prudent behaviors under Knightian uncertainty, the book applies these ideas to economic models that include portfolio inertia, indeterminacy of equilibria in the Arrow-Debreu economy and in a stochastic overlapping-generations economy, learning, dynamic asset-pricing models, search, real options, and liquidity preferences. The book then proceeds to characterizations of pessimistic (ε-contaminated) and optimistic (ε-exuberant) behaviors under Knightian uncertainty and people’s inherent pessimism (surprise aversion) and optimism (surprise loving). Those characterizations are shown to be useful in understanding several observed behaviors in the global financial crisis and in its aftermath. The book is highly recommended not only to researchers who wish to understand the mechanism of how pessimism and optimism affect economic phenomena, but also to policy makers contemplating effective economic policies whose success delicately hinges upon people’s mindsets in the market. Kiyohiko Nishimura is Professor at the National Graduate Institute for Policy Studies (GRIPS) and Professor Emeritus and Distinguished Project Research Fellow of the Center for Advanced Research in Finance at The University of Tokyo. Hiroyuki Ozaki is Professor of Economics at Keio University.

Economic theory offers several explanations as to why shifting expectations about future economic activity affect current demand. Abstracting from whether changes in expectations originate from swings in beliefs or fundamentals, we test empirically whether more optimistic or pessimistic potential output forecasts trigger short-term fluctuations in private consumption and investment. Relying on a dataset of actual data and forecasts for 89 countries over the 1990-2022 period, we find that private economic agents learn from different sources of in- formation about future potential output growth, and adjust their current demand accordingly over the two years following the shock in expectations. To provide a theoretical foundation to the empirical analysis, we also propose a simple Keynesian model that highlights the role of expectations about long-term output in determining short-term economic activity.

"Many economists feed today's pessimism with regard to the future. Peter De Keyzer is a welcome exception. Yes, there are problems, but this book shows that there are also solutions. There is reason for optimism." - Professor Paul De Grauwe, London School of Economics "The economy has to keep growing." So says top economist Peter De Keyzer. In his view, a free market and intelligent growth are necessary for our continued wealth and well-being. Better yet: economic growth is the only recipe for guaranteeing more freedom and more prosperity for all. Nevertheless, after nearly five years of crisis, one no longer seems to believe in economic progress. Growth Makes You Happy is a solidly argued plea in favour of more optimism, more risk, less collectivism, and more freedom.

Are firms' expectations systematically too optimistic or too pessimistic? Does it matter? We use micro data from the West German manufacturing subset of the IFO Business Climate Survey to infer quarterly production changes at the firm level and combine them with production expectations over a quarterly horizon in the same survey to construct series of quantitative firm-specific expectation errors. We find that depending on the details of the empirical strategy at least 6 percent and at most 34 percent of firms systematically over- or underpredict their one-quarter-ahead upcoming production. In a simple neoclassical heterogeneous-firm model these expectational biases lead to factor misallocations that cause welfare losses which in the worst case are comparable to conventional estimates of the welfare costs of business cycles fluctuations. In more conservative calibrations the welfare losses are even smaller.

Psychologists have long been aware that most people maintain an irrationally positive outlook on life—but why? Turns out, we might be hardwired that way. In this absorbing exploration, Tali Sharot—one of the most innovative neuroscientists at work today—demonstrates that optimism may be crucial to human existence. The Optimism Bias explores how the brain generates hope and what happens when it fails; how the brains of optimists and pessimists differ; why we are terrible at predicting what will make us happy; how emotions strengthen our ability to recollect; how anticipation and dread affect us; how our optimistic illusions affect our financial, professional, and emotional decisions; and more. Drawing on cutting-edge science, The Optimism Bias provides us with startling new insight into the workings of the brain and the major role that optimism plays in determining how we live our lives.