The Four Big Risks

Definition

Cagan names four distinct kinds of risk that any product idea carries: value risk (will customers choose to buy or use it), usability risk (can users figure out how to use it), feasibility risk (can engineers actually build it with the time, skills, and technology available), and business viability risk (does the solution work for sales, marketing, finance, legal, and the rest of the business). His claim is not merely that these risks exist, but that strong teams address all four with real evidence before deciding to build — not the product manager's opinion, but data from real users, real engineers, and real stakeholders.

In the Book

Chapter 7 introduces this as the first of three principles that separate teams who have moved "beyond Lean and Agile" from teams still practicing a diluted version of both: "risks are tackled up front, rather than at the end." Chapter 33 ("Principles of Product Discovery") expands each risk and states plainly that the purpose of product discovery is to address exactly these four questions. Cagan is explicit that feasibility and business viability are too often treated as afterthoughts — checked only once engineering starts building, or once legal and sales get involved late — and that this is "usually the underlying reason" teams grossly underestimate what a project will take. He illustrates the mechanism with the feasibility prototype (Chapter 46): a small piece of throwaway code an engineer writes in a day or two, purely to resolve whether a specific technical approach will work, done as discovery work rather than delivery work, before any commitment is made.

The book also names an optional fifth risk — ethics, "should we build it?" — which Cagan treats as increasingly necessary alongside the traditional four as technology products gain the power to cause real-world harm.

Why It Matters

Most product failures are not failures of execution — the team builds exactly what was specified, on time, working correctly — but failures to have asked the right question before building at all. Separating "will this work" into four independent, testable dimensions gives an organization a checklist that catches different failure modes: an idea can pass value and usability testing and still be un-shippable because it violates a legal constraint, or it can be technically trivial and still fail because nobody wants it. The general lesson — that a single "will this succeed?" judgment actually bundles several independent uncertainties that should be tested separately, cheaply, and early — applies to any domain where commitment is expensive and reversal is costly.