Unlike conspiracies and intrigues, which are plots to carry out unlawful acts, rebellions or coups, a conspiratorial worldview is a comprehensive approach, usually termed conspiracism, that deciphers the world as driven by conspiracies and intrigues. Departing from this distinction, the chapter analyses the logics of conspiracism, claiming that it operates on a logic that is no less coherent than scientific discourse, while differing from the latter in two major respects: in their verification and discard methodology as well as in their mobilising role. It also sustains that while recognising the universal tendency to give credence to conspiracy narratives, research should identify the specific historical, social and geopolitical circumstances that explain why and when societies fall for the allure of conspiratorial narratives. The text addresses the impact of conspiratorial ideas and the varied historical and recent scenarios of their crystallisation. It then outlines the implications in the contemporary context of institutional distrust, misinformation and fake news.