Introduction—A return to form

Starting roughly thirty years ago, essences and essentialism has seen a gradual rise in interest and support, not only as measured in the number of publications, but also in terms of applicability to distinct philosophical issues. This special issue showcases this wide applicability. Michail Peramatzis opens with a paper on Aristotle. On Aristotle's hylomorphism, a substance such as Socrates is made up of both material parts and a form, namely that of being a human. The issue of the paper concerns how and what makes these parts into something unified, namely Socrates. Peramatzis defends an integrated reading of Metaphysics Ζ.12, Ζ17, and Η.6, and the position that the compound's unity is derivative of the form's primitive unity. This paper will be of interest not only to scholars of Aristotle, but also to metaphysicians working on hylomorphism and the problem of unity. Naomi Thompson contributes a paper on the relatively recent topic of metaphysical explanation, namely as explanations fundamentally distinct from causal explanations, typically exemplified by the relation of grounding. Her paper provides much needed clarity on the possible antirealist positions available, explores the connections between these positions, and lays out the reasons for and against each of them. This paper will be instrumental in shaping future research on antirealist positions on metaphysical explanation. Robin Hendry defends microstructural essentialism for chemical substances: the position that the molecular structure is what determines the identity of a chemical substance. With a detailed range of examples from chemistry, Hendry explains the notion of structure, presents the arguments for microstructural essentialism, and replies to the counterarguments in the literature. In the final section, the paper discusses the Aristotelian problems of mixture, especially in the case of super-heavy elements like oganesson. Presupposing a broadly Aristotelian view, Hendry argues that oganesson the element does not exist because its characteristic nuclei does not exist long enough to exhibit the element's characteristic powers. Jessica Leech seeks to reintroduce Barcan Marcus' account of the relation between essence and necessity, that of minimal essentialism. Leech shows that Barcan Marcus, in common with several of her contemporaries in the late 60's and early 70's, did recognise the distinction, famously made by Kit Fine, between essential properties and properties that are merely necessary. Moreover, she argues that minimal essentialism is able to adequately deal with the problematic cases raised by Fine, and therefore that Barcan Marcus' account should be a serious contender in the current discussion of modality and essence. Ludger Jansen explores the applicability of essences to the social domain. He argues that essences are to be found for both social kinds and for social identities. However, these two variants exhibit essences with radically distinct characteristics. Social kinds are extrinsically constituted, namely in some historical social act, while social identities are internally constituted, namely in some mental act. And while social kinds are stable and immune to change, social identities can be replaced and changed. Jansen explores the benefits of endorsing essentialism in the social domain, and rebuts the possible objection that essentialism is dangerous because it supports oppressive social structures. Acceptance of essentialism in fact turns out to be a necessary precondition for ending these oppressive structures, by identifying the essential features of the oppressive structure, thereby pointing out how these oppressive structures can be ended. Kathrin Koslicki and Olivier Massin contribute a paper on metametaphysics. In response to the recent neo-Carnapian view that definitional disputes—for instance the what-is-F disputes found in Socratic dialogues—turn out to simply be verbal disputes (see for instance the work of Amie Thomasson), they instead argue that such disputes are typically substantive. Moreover, the resolving of such disputes presuppose an ontological commitment to essences, specifically that ‘some […] phenomena have essences, and that these essences can be rigorously studied by philosophical or scientific means.’ (Koslicki & Massin, this issue, pp. 319-333) And while the authors do not deny that there are also verbal disputes, what is typical of these cases is that instead of a single phenomenon we find out that there are two distinct phenomena, and argue that such cases require the recognition of more, not fewer, essences. Jeremy W. Skrzypek develops an account of Aristotle's hylomorphism which takes into account the insights of the recent literature on biological processualism, especially the view of Dupré. The resultant position, which Skrzypek following Mark Steen calls ‘hyloenergeism’, is able to capture these insights without abandoning the Aristotelian commitment to essences and to substances, and is argued to have further theoretical advantages compared to Dupré's position. While this is a systematic paper, at the end of the paper Skrzypek also suggests that hyloenergeism might in fact have been Aristotle's actual position. Martin Glazier presents an objection to priority monism, which is the position recently defended by Jonathan Schaffer that there is only one substance, viz. the whole cosmos. The objection is that priority monism violates the basic tenet that every substance is necessarily a substance, because it turns out that the cosmos is not necessarily a substance, and thus that priority monism is false. Glazier discusses Schaffer's three arguments, and shows that neither justifies a rejection of the tenet that every substance is necessarily a substance. Further, Glazier shows that this tenet poses a problem for a distinct issue, namely what Schaffer calls the ‘Aristotelian principle’: that no substance is composed of substances. Finally, the pluralist position that there are many substances, viz. mereological simples, is argued to not violate the tenet that every substance is necessarily a substance. Of the papers in this issue, four were presented at the annual Ratio conference 2022. This was organised as a hybrid conference, with 18 live and 24 virtual participants registered. Robin Hendry, Michail Peramatzis, and Naomi Thompson presented their papers in Reading, while Ludger Jansen did his presentation remotely. Once more I want to thank the speakers, the participants, the staff and caterers involved, and especially David Oderberg, for making the event run smoothly and successfully. The other four papers, by Martin Glazier, Kathrin Koslicki & Olivier Massin, Jessica Leech, and Jeremy W. Skrzypek, were commissioned for this special issue. Both the Ratio conference and my own position while organising and editing this issue, was funded by the European commision through my MSCA individual fellowship, Formal Causation: Rivals and Extensions (FCRE 101028122).