In this new book, Bruno Latour offers answers to questions raised in We Have Never Been Modern, a work that interrogated the connections between nature and culture. If not modern, he asked, what have we been, and what values should we inherit? Over the past twenty-five years, Latour has developed a research protocol different from the actor-network theory with which his name is now associated--a research protocol that follows the different types of connectors that provide specific truth conditions. These are the connectors that prompt a climate scientist challenged by a captain of industry to appeal to the institution of science, with its army of researchers and mountains of data, rather than to "capital-S Science" as a higher authority. Such modes of extension--or modes of existence, Latour argues here--account for the many differences between law, science, politics, and other domains of knowledge.