Page's book is one of the landmark books on the topic of diversity of thought, or collective intelligence. He approaches the topic like a mathematician or computer scientist, devoid of any emotional or ideological intentions, analysing how choices can be made by different people, and how the outcome of problem-solving can be improved if diverse perspectives are combined.
He creates a number of theorems that he systematically investigates. He defines all the difference that people may have in their approach to a problem. He defines 'perspectives', 'heuristics', 'interpretations', 'tool boxes' and 'preferences'. He calculates how adding every person's individual set of perspectives, heuristics, interpretations, tool boxes and preferences to another person's, increases the list of possible solutions to a problem with a huge factor.
His conclusion is clear : Diversity Trumps Ability. Collective decision-making will increase the predictive power, will generate more creative ideas, will come to more and better solutions to problems, and will obviously know more facts ... But Page is also clever enough to put some conditions against this strong evidence. It does not work in all situations and in all contexts. It should fit the purpose. A random group of people will not solve a mathematical problem better than a mathematical expert on his own. And it is not because you have good identity diversity (ethnic, gender, age group) in teams, that you have the best possible diversity of perspectives: if they all have the same social and educational background, they may be less diverse than you think.
Page writes well, and like any scientist, his approach his very systematic and in-depth, but he manages to keep it readable, with examples and reasonings that do not require any specific knowledge of mathematics, economy or computer science.