Essentialism and modal dispositionalism are two rival theories of metaphysical modality. According to essentialists (especially Fine 1994a, Koslicki 2011, Lowe 2012, Hale 2013), modality is grounded in the essence of things, but, according to modal dispositionalists (Borghini and Williams 2008, Jacobs 2010 and Vetter 2015), it depends on the dispositions they instantiate[1]. My aim will not be to settle which theory is better suited to account for modality, and whether they may be combined. My aim will be to investigate in the relationship between the notions of essence and dispositions, and show that essence may be reduced to dispositions. If successful, this reduction would be a crucial element in the theory choice. For dispositions to reduce essence, they must play three major roles: 1) to distinguish between two sets of properties had by an object, corresponding to the essential/accidental properties distinction; 2) to provide real definitions; and 3) to show that since dispositions are more fundamental than essence, they are also hyperintensional notions, or at least not closed under logical implication, that is providing more fine-grained distinctions than modal notions. 

Before presenting the core of the reduction, it is important to examine why, contra Vetter (2021), essence are not simply constraining dispositions, as she suggests. She argues that there is a relation of semi-duality between the two notions: essence constrains disposition[2], but not the other way around. However, this asymmetric relationship has been challenged by Koslicki (2022) who argued that the dependence may also go in the other way: there are cases where we cannot express the essence of an object without referring to its dispositions. She especially refers to the cases of artifacts. If we accept the standard view about artifacts, their essence lies in their function. This latter defines a set of preferential dispositions. But this is still not satisfying for my project, for two reasons: 1) this dependence may appear as accidental. It works with artifacts, but maybe not with every kind of objects, and it is not built into the nature of the notion de essence; and 2) the function also needs the notion of essence in order to distinguish between essential and accidental dispositions (e.g. to distinguish cases of malfunctioning). This is why I must go further in the reduction and present a general model without any reference to essences. This, I suggest, may be achieved in three steps: 

First, I extend the scope of dispositional properties. In the standard conception of dispositions (especially Bird 2007; 2016; 2018), they are fundamental physical properties, such as mass or charge, which only applies to fundamental objects. Essence, on the other hand, may characterize everything whatsoever. It seems to be a much more flexible notion. I will argue 1) that dispositions may be extended to non-fundamental objects (following roughly the explanatory dispositionalism of Vetter 2015; 2018b), such as ordinary objects (organisms, table, chairs) or social objects (groups, institutions). In fact, dispositions are posited whenever they may explain a phenomenon. 2) I will argue that dispositions are not only causal properties as usually understood, but may also be normative, teleological (as argued by Paolini Paoletti 2021), compositional (parts may have the disposition to compose a whole), probalistic (see Nolan 2015) ... And finally, 3) there is the question of abstract objects. Following again Vetter (2018a), I will argue that mathematical or logical objects may have dispositions. For instance, we may say that a conjunction has the disposition to yield a specific truth-table. 

The second step will be to present a special kind of dispositions such that it could play the three roles expected. I will introduce the notion of structural disposition. This notion has been especially developed by Austin and Marmodoro (2017), and Marmodoro (2017). However, I want to remain neutral with regard to their metaphysical assumptions. This why I will present my own interpretation of structural dispositions: SD is a structural disposition of an object x iff SD i) continuously manifests itself; ii) manifests as the unification of a set of properties of x such that they ground all of its other properties; and iii) that this unification is definitional of x. Structural dispositions are then continuously manifesting dispositions which structures the object. The notion of essence would be too coarse-grained to account for this unification. Furthermore, it also accounts for the distinction between essential and accidental properties. Structural dispositions characterize fundamental objects, non-fundamental objects, and abstract objects.

Finally, the final step consists in showing that structural dispositions are not closed under logical consequence. According to Vetter (2015; 2021), dispositions are closed under logical implication, that is, if an object is disposed to j and that j logically implies that y, then it is disposed to y. This is not true of structural dispositions. Those latter may be claimed to be constitutive and not consequential (according to Fine 1994b conception). According to Yates (2013) and Giannini and Mumford (2021), it is also possible to distinguish between the structural disposition and what the scholastics call the propria, that is everything which flows from the essence of the object. For instance, every charged particle has a mass superior to the electronic mass. However, it doesn't seem that this characteristic is constitutive of a charged mass. It is not part of its structural disposition, but it flows from it. In this sense, it would seem that structural dispositions may present the same distinctions as essence, and be an hyperintensional notion, providing more fine-grained distinctions than modality. 

If I am right, dispositions may have the theoretical benefits of essence, and anyone who wants to do without a primitive and explanatory notion of essence could use structural dispositions.