The overview -- The plan of the book -- Group to individual, or vice vera? -- The Williams problem and utopias -- Group rationality : a unique problem -- Not an evolution problem -- Not a game theory problem -- Ramsey and group rationality -- The problem explored : Sen's way -- Consistency, ordering, and rationality -- Other notions of rationality and scientific welfare -- The sen-problems of group rationality -- The problem defined -- The skeptical view -- The democratic councils -- No covenant, a tale -- Multiply, multiply, multiply -- Positive arguments -- Negative arguments -- The route to the goal -- The subjectivist view I -- Individuals, group, and goals -- Divisions and discrepancies -- A society of ruthless egoists -- Theory choice -- Problems and a paradox -- The subjectivist view II -- Values and individuals -- Group transitions and risk distribution -- History, values, and representative groups -- Negotiations in the scientists' original position -- The city of man? -- The objectivist view -- Two objectivist problems -- Toward the best available method -- The best available method -- Is the single method sufficient? -- A new problem of demarcation -- Illustration : the herbalist tradition -- The scare of Saint-Simon -- Putnam, individual rationality, and Peirce's puzzle -- Democracy and group rationality -- Moral images, scientific images -- Method, historical knowledge, and reason -- Peirce's puzzle -- Ultimately, relativism? -- What lies at Bedrock -- The nine problems -- The problem, the common aim of science, and the basic structure -- The council, reasoning, and allegiance -- The universal law of rationality, the worth of science and utopias.