This book is the second in a series of discussions about the 'great minds' in the history and theory of finance. The first book described the role of returns in our personal financial decisions. This second book adds risk and uncertainty to the mix. I investigate how our treatment of risk and uncertainty necessitated a new understanding of probability. The creation of this fresh treatment for probability induced us to rewrite and to generalize our understanding of financial returns that must be balanced with risk. While the modeling of risk dramatically complicated our models in finance, it also answered questions that, to then, challenged our understanding of financial markets and equilibrium. These great minds answered the following questions: What is the meaning of probability, risk, and uncertainty? How does risk and uncertainty affect our financial well-being? How does an individual balance the return/risk tradeoff? How can we use these tools to diversify our risk and optimize our portfolio? And, how does the market aggregate the decisions of myriad risk averse personal financiers? I examine probability, risk, and uncertainty through the contributions of John von Neumann and Oskar Morgenstern, Leonard Jimmie Savage, Kenneth Arrow, and Harry Markowitz. , These Portfolio Theorists provided us with a dramatic leap forward in our understanding and insights of financial rewards under risk and uncertainty.

In fact, their results are perhaps more significant and groundbreaking than any other financial theorist before or since. Such brilliance is the hallmark of a great mind.