Why do economies exhibit sustained growth in per capita income? This paper argues that endogenous fertility and increasing returns to scale are the fundamental ingredients in understanding endogenous growth. Endogenous fertility leads the scale of the economy to grow over time. Increasing...

At least since 1950, the United States has been stimulated by increases in educational attainment, increases in research intensity, and the increased openness and development of the world economy. Such changes suggest, contrary to the conventional view, that the U.S. economy is far from its...

In many models, economic growth is driven by people discovering new ideas. These models typically assume either a constant or a growing population. However, in high income countries today, fertility is already below its replacement rate: women are having fewer than two children on average. It is...

This paper considers the taxation of top incomes when the following conditions apply: (i) new ideas drive economic growth, (ii) the reward for creating a successful innovation is a top income, and (iii) innovation cannot be perfectly targeted by a separate research subsidy --- think about the...

The nonrivalry of ideas gives rise to increasing returns, a fact celebrated in Paul Romer's recent Nobel Prize. An implication is that the long-run rate of economic growth is the product of the degree of increasing returns and the growth rate of research effort; this is the essence of...

New ideas are often combinations of existing goods or ideas, a point emphasized by Romer (1993) and Weitzman (1998). A separate literature highlights the links between exponential growth and Pareto distributions: Gabaix (1999) shows how exponential growth generates Pareto distributions, while...

During the Covid-19 pandemic, the United States effectively "spent" about 4 percent of GDP -- via reduced economic activity -- to address a mortality risk of roughly 0.3 percent. Many experts believe that catastrophic risks from advanced A.I. over the next decade are at least this large,...

This brief note revisits the proof of the Steady-State Growth Theorem, first provided by Uzawa (1961). We provide a clear statement of the theorem and a new version of Uzawa's proof that makes the intuition underlying the result more apparent

Health care extends life. Over the past half century, Americans have spent a rising share of total economic resources on health and have enjoyed substantially longer lives as a result. Debate on health policy often focuses on limiting the growth of health spending. We investigate an issue...

Top income inequality rose sharply in the United States over the last 35 years but increased only slightly in economies like France and Japan. Why? This paper explores a model in which heterogeneous entrepreneurs, broadly interpreted, exert effort to generate exponential growth in their incomes....