Make the Call

Knowing what you know, learning what you can, and acting under uncertainty in entrepreneurship

Preface

A word before we begin, because this book is not quite what its shelf suggests.

It is about making decisions when you cannot get the facts first — the actual, daily work of building something new. It is not a business-analytics textbook, though it will sharpen how you use evidence; it is not a growth playbook or a bag of startup tactics. It is a method for reasoning under uncertainty, drawn from how scientists, statisticians, and clear-headed founders actually think, and made practical enough to use on the decision in front of you this week. If you have ever had to commit to something before you could be sure of it, it is written for you, and you need no technical background to read it. If what you want is certainty, or formulas to plug numbers into, or a list of hacks, this is honestly the wrong book. It offers judgment rather than shortcuts, and it does not pretend judgment is easy.

A few things about how it is written will stand out, and each is a choice. It is short and plain, because deciding under uncertainty is hard enough without prose that shows off. It carries almost no mathematics: the reasoning underneath is genuinely mathematical, Bayesian to give it its name, but you will never be asked to do algebra, the ideas are taught in plain counting and pictures, and the few formulas that exist wait in the margins for the curious. It is relentlessly a how-to, every part ending in something to try, with one venture carried from the first page to the last so you always see the method working on a real decision rather than in the abstract. And it assumes you have an AI at your elbow, because you do — rather than pretend that tool away, the book puts it to work throughout, while staying clear about the one thing it cannot do for you, which is decide.

What it promises is narrow, and I think honest. Not certainty: no truthful book about uncertainty could offer that, and the ones that do are the ones to distrust. It promises that you can learn to decide well without certainty, which is the more useful thing, because it is the thing you can actually have.

So bring a decision — something real you are facing, or about to. Read with it in mind, and by the last page you will have made at least one call better, and begun to become someone who makes them well.