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Secrets, absences, silences, gaps, and deferrals: much of my research has been dedicated to understanding the relevance, for social life and technical expertise, of what is not present. In examining the enforcement of rules, the construction of categories, and the establishment of prohibitions, I have sought to find ways of promoting inquiry into situations in which the control of information is highly managed. Join me in asking how revelations conceal, how secrets are kept by being shared, and how ignorance is studiously achieved. All will be revealed.