The international relations theorist Robert Cox famously made the claim that ‘[O]ntologylies at the beginning of any enquiry’(1992, 132). For Cox, it is necessary to presuppose a certain basic structure that consists of certain types of entities. One of the results is that any analysis of political problems cannot avoid ontological questions or assumptions.This does not mean that political beliefs or ideologies are correlated with or determined by one’s ontology, but rather that politics cannot escape ontological questions or pre-suppositions regarding certain entities, structures or systems. In this vein, one of the greatest contributions of Bruno Latour throughout his work has been his arguments regarding ontology. The publication of An Inquiry into Modes of Existence(2013) has seen a significant shift in the focus of Latour’s thought, proposing a pluralist ontology of 15 different coexisting modes of existence. The desire to trace this shift, and Latour being interpreted as a metaphysician (Harman2009,2014), has been the main motivation for producing this collection of articles and book review symposia, all of which focus on understanding the relationship between the later Latour and politics. A simple but productive distinction of Latour’s work would be to understand his work as contributing two different but connected social ontologies. There is the ontology of the early and middle Latour, which is an ontology of various heterogeneous actants and is associated with actor-network-theory. It is arguably this Latour that is the most prominent in the collective consciousness of the social sciences and has been the catalysis for stimulating further research and debate. Interestingly, Latour’s actor-net-work-theory has received criticism from both scientific and social constructivist perspectives. The former criticise actor-network-theory for being subjectivist and lacking objectivity, while the latter critique actor-network-theory for being too realist and neglecting cultural and contextual factors. As Harman notes, receiving criticism from both sides suggests that Latour is working on something worthwhile. The second ontology is that of the later Latour, where the focus is turned to modes of existence,rather than focusing on networks or actants. It is here that Latour attempts to answer a key question: if we have never been modern, then what have we been? For Latour, the answer is the moderns have existed through 15 different modes of existence, which I discuss later in this introduction.