Entrepreneurs are everybody’s darlings these days. They may be small, but they are innovative. And innovation, we are assured, is the main engine of economic growth. For policymakers everywhere, the task is to get the little critters to nest and breed. Give them the conditions they like--plenty of venture capital, tax breaks and a risk-taking culture—and the sun will shine on all of us, just like in California. Along comes Amar Bhide to tell us most of this is plain wrong. Entrepreneurs, he asserts, are not risk-takers at all. Nor do most of them innovate, or depend on venture capital. His findings are striking enough. Start with his assertion that entrepreneurs are not innovators or risk-takers. The vast majority of new businesses, he points out, start small and stay that way. These are the hairdressing salons, corner shops and landscape gardeners. Those are mature, predictable industries. For just that reason, they are the least profitable. The success stories come in areas of high uncertainty, where markets are changing fast because of technology, regulation or fashion. A very large proportion, unsurprisingly, are in computing. But Mr. Bhide insists they are rarely innovative. The people who start high-growth businesses take a humdrum idea, usually from someone else, then change it constantly to fit the market. The starting point is much less important than what happens next. Nor are they risk-takers. These are typically young people, with no money, expertise or status. They have nothing to lose. Risk arrives later on, when they have made their pile and must decide whether to invest in long-term growth or sell out. This is one reason why so few promising start-ups become a Dell or Microsoft. Taking planned, calculated risks is the job of big, established companies, Mr. Bhide argues. True entrepreneurs rarely have the temperament for it. What they have, instead, is a high tolerance for ambiguity--defined as knowledge that you know you do not have. Few of Mr. Bhide’s interviewees began with any kind of business plan. That would have been a waste of time: the future was simply too uncertain. Therein lay their opportunity. Big companies may be happy with risk, but they cannot stand ambiguity. They can invest billions in a chip plant or oil field, but only when they know the odds. When the odds are unknown, entrepreneurs have the game to themselves.