This book explains how our understanding of probability affects our everyday lives. It is designed to explain the thinking behind those decisions in plain English and to provide tools to improve how those choices are made. From the moment we wake until we go to sleep we intuitively make probability choices. Many aspects of life appear to be random but actually fall into knowable patterns. Every choice we make in every aspect of our lives - money and investing, relationships, sports, nutrition, professional activities and jobs, ... everything we decide can be improved by an understanding of probability.

This book is intended for people who realize that probability theory is an important subject, but who shy away from formulas and mathematical symbols. It is not a rigorous logical proof of probability theory nor is it a guide to calculating complicated probability problems. It is designed for people who are open to learning about ways to make more successful decisions in their everyday lives from a book written in nonmathematical language.

Some people have moral objections to gambling, and probability theory has nothing to say about the morality of gambling. However, it was gamblers who started the intellectual revolution that led mathematicians to reimagine our approach toward the world and everything we know about it. As a result, we know that we can have an impact on our future. We are not simply pawns in a larger game determined by forces beyond our control.

If we are conscious of the choices we make and why we make them, and if we are able to clearly understand and calculate risk vs. reward in common situations, we should be able to make decisions that will positively impact our lives. Modern mathematicians, scientists and philosophers have developed tools to understand and harness the apparent randomness in our lives in a way that manages risk, and gives us a degree of control over our lives that was unknown in pre-modern civilizations. If we understand the patterns in the world, we can take advantage of that understanding. Understanding these patterns is the purpose of the book.

Probability theory has been derived over the last five centuries using algebra, geometry, calculus, game theory, set theory, chaos theory and other forms of mathematics. However, the fundamental ideas can be explained without any of these tools. It is possible to understand the basics of probability theory with nothing more than simple logic, our own experience, and the ability to add, subtract, multiply and divide.

Everyday life has changed more in the past few hundred years than it did in the prior several thousand years because of this modern conceptual understanding of the world around us. We have so thoroughly adopted this modern mindset that it is hard for us to understand the thinking of people who lived before this incredible intellectual revolution. We can only wonder at the fact that humanity existed and developed for thousands of years without the benefit of these statistical insights that we now consider common logic.

While we can never fully comprehend how people thought in premodern times, we can at least try to understand the world they faced and how they tried to cope with it. We'll start in Chapter One by contrasting modern probability logic with common logic in pre-modern times.

This book is about a lot of seemingly disparate topics that may not at first glance appear to have much in common. Survey research, horse racing, Monty Hall and satellites falling from space and landing on you, may not seem to have much in common, but they do. They are all understandable, and they are all tied together, if we view the world through probability theory.

After you become comfortable with these ideas and use them for a short while they will begin to seem quite obvious. Your decisions will begin to seem so obvious to you that you will wonder that you ever thought any other way, or that other people still do. You'll begin to see everything in these terms and your decisions will be easier, quicker and more successful. No one gets them all right, but there is a way to get more of them right than you used to.