Intensionalists claim that necessarily equivalent propositions are identical; hyperintensionalists deny this. Whereas possible worlds semantics provides a canonical intensional framework, there is no canonical hyperintensional framework. Recent years have rather seen a thousand flowers bloom with the development of truthmakers semantics, aboutness theory, grounding theory, and logics of essence, to mention but a few hyperintensionalist theories.

A lot of recent work has focused on various paradoxes that threaten hyperintensionalism - the so-called Russell-Myhill paradox in particular. We now have reason to think that these paradoxes can be resolved.

The mere consistency of hyperintensional theories does not, obviously, mean that they are worth having. Even staunch adherents of hyperintensional approaches would admit that they are more complicated than their intensional competitors. So, what work can be done by hyperintensional theories that cannot be done by their intensional competitors? Is the work being done worth the price of the greater complexity? The goal of the workshop is to bring together some leading proponents and opponents of hyperintensionalism to discuss these questions.

The workshop will be held at St John's College, Oxford, 1-2 OCtober 2026.

We will be in the Mark Bedingham Room, in the Library and Study Centre.

Registration is now closed. If you have not registered and would like to attend, please contact Nicholas Jones.

Schedule

1 October

09.25-09.30: Welcome

09.30-10.45: Introductory remarks (Jones, Linnebo, Litland)

Chair: James Kirkpatrick

10.45-11.00: coffee break

11.00-12.15: Gideon Rosen, "Worldly Hyperintensionality and the Metaphysics of Explanation"

Chair: Óscar Monroy Perez

12.15-1.30: lunch

1.30-2.45: Andreas Ditter, "Non-Naturalism, Supervenience, and Essentialism about Modality"

Chair: Ho Yeung (Frank) Lee

2.45-3.00: break

3.00 - 4.15: Friederike Moltmann, "Object-Based Truthmaker Semantics and the Generation of Modal Objects"

Chair: Jacopo Berneri

4.15-4.45: coffee & cake break

4.45 - 6.00: Fabrice Correia, “Factual Equivalence, Its Logic, and Higher-Order Identity”

Chair: Nicholas K. Jones

2 October

09.30-10.45: Timothy Williamson, "Semantically Complex Directly Referential Expressions"

Chair: Øystein Linnebo

10.45-11.00: coffee break

11.00-12.15: Anna Mahtani, "Hyperintensionality and Action-Guiding Principles"

Chair: Jacopo Berneri

12.15-1.30: lunch

1.30-2.45: Nicholas K. Jones, "Hyperintensionality, Opacity, Deep Strcuture"

Chair: Davide Sutto

2.45-3.00: break

3.00 - 4.15: Stephan Krämer, "Intensional Ground?"

Chair: James Kirkpatrick

4.15-4.45: coffee & cake break

4.45 - 6.00: Benjamin Schnieder (TBC)

Chair: Jon Litland

Abstracts

Moltmann, "Object-Based Truthmaker Semantics and the Generation of Modal Objects"

Abstract: Objects-based truthmaker semantics takes truthmaking conditions to not only pertain to sentences, but also various objects that naturally act as bearers of satisfaction conditions, such as attitudinal objects like claims and desires, and modal objects like needs, offers, dispositions, permissions, and obligations. This talk will focus on the various ways in which modal objects may be generated from given entities or conditions, such as essences and abstract wholes with their concrete realizations. The latter yield modal objects of the sort of 'lacks', the basis of the semantics of the modal verb 'lack', which gives particular motivations for truthmaker semantics applied to objects.

Correia, "Factual Equivalence, Its Logic, and Higher-Order Identity"

Abstract: Factual equivalence—the notion expressed by ‘Its being the case that ... and its being the case that ... are one and the same thing’ and other similar sentential operators—has been an important topic of discussion in metaphysics and philosophical logic over the past few years. In this talk, I will first defend, against two recent attacks, a logic of the notion that I advocated a few years ago. In reply to one of the attacks, I argue that contrary to what many seem to have thought, factual equivalence is not a (higher-order) notion of identity. In the final part of the talk, I will tentatively argue that factual equivalence can be defined in terms of a “two-sided” counterpart of the notion, which does have some claims to qualify as a notion of identity.

Kramer, "Intensional Ground?"

Abstract: It is widely held that ground is hyperintensional; many plausible claims about ground seem plainly incompatible with an intensional view of the phenomenon. Intensionalists accordingly tend not to propose an intensional account of ground but instead to dismiss the very idea of ground. Still, it seems worth asking: what is the best theory of ground available under intensionalism? (And how does it compare to extant hyperintensional theories?) In my talk, I explore some ideas for an intensional account of ground.