I’m not sure I’m up to tackling the book itself, but Henry at Crooked Timber has an informative review of University of Michigan political scientist Scott Page’s The Difference: How the Power of Diversity Creates Better Groups, Firms, Schools and Societies:

“There are quite plausible conditions under which groups composed of diverse individuals will be able to outperform groups of ‘experts;’ individuals who are better capable of solving problems on their own. Page uses some simple agent-based modelling to support this claim, and outlines the underlying logic of a ‘mathematical proof that provides sufficient conditions for the … result.’ The necessary conditions are that there have to be enough agents, groups of moderate size, agents who are sufficiently smart, and problems that are sufficiently difficult. The reason why this result holds is fairly straightforward; experts tend to be quite like each other, so that they tend to converge on the same solution, while heterogenous agents have a better chance of coming across other, superior solutions. This suggests both that there is an important role for diverse groups of non-experts, and that the dumbed down versions of the Wisdom of Crowds thesis don’t hold (i.e. that experts will still beat people who don’t have a clue about the underlying problem).”

There’s more, with appropriate qualifications. One important qualification is that the situation needs to be set up so that the diverse people communicate well with one another.