We are happy to anounce that Diagrams 2022 will have two keynote speakers. Furthermore, the Graduate Symposium will have an Inspirational Early Career Researcher invited talk.

**Keynote Speaker Gem Stapleton**

**Title:** *The Power of Diagrams: Observation, Inference and Overspecificity*

In order to effectively communicate information, the choice of representation is important. Ideally, a chosen representation will aid readers in making desired inferences. The ability of diagrams to convey information effectively comes, in part, from their tendency to make facts explicit that would otherwise need to be inferred. This diagrammatic benefit has often been referred to as a free ride, which has recently been generalized to the notion of an observational advantage. In this talk, I will present the theory of observation – capturing when one statement is observable from another – which exploits relations between syntactic elements of representations that convey meaning. Using the concept of observability as a basis, I will give a formal characterization of the observational advantages of one representation over another. By considering observational advantages, people will be able to make better-informed representation choices. To exemplify the theory, I will show that Euler diagrams *sometimes* have numerous observational advantages over set-theoretic statements. This formally justifies Larkin and Simon’s claim that “a diagram is (sometimes) worth ten thousand words”.

This is joint research with Atsushi Shimojima and Mateja Jamnik.

** About Gem Stapleton: **Gem’s interests are firmly situated in the study of diagrams, encompassing their mathematical properties and cognitive effectiveness. Her multi-disciplinary research aims to expose how we can effectively design and apply diagrammatic representations in order to communicate, and reason about, information. She is perhaps best known for her ground-breaking contributions towards the development of diagrammatic logics alongside methods to automatically draw diagrams as visualizations of information. Gem’s current research is creating novel mechanisms to facilitate representation change in order to enhance human understanding. As leading figure in the Diagrams community, Gem has been highly influential in the direction of diagrams-related research as well as the Diagrams conference series. Having previously been Director of the Visual Modelling Group at the University of Brighton, she is now a Visiting Fellow at the University of Cambridge.

**Keynote Speaker Sun-Joo Shin**

* Title: Visual Representation and Abductive Reasoning*G. Polya recommends we find a way to represent non-geometrical problems geometrically in his

*How to Solve it*. On the other hand, we do not find any recommendation of non-geometric representation for geometrical problems. This well-accepted asymmetrical approach suggests that we explore advantages of visual representation in the process of solving a problem. Highlighting a hierarchical structure of our reasoning, I identify certain features of visual representation which guide us at a meta-reasoning level. For example, various ways of grouping, re-grouping and de-grouping, I show, facilitate our abductive reasoning. Moreover, through case studies, I claim we prefer representational systems that allow the flexibility of recognizing various patterns.

* About Sun-Joo Shin: *Sun-Joo Shin is a professor in the Department of Philosophy at Yale University. She is the author of

*The*

*Logical Status of Diagrams*and

*Peirce’s Iconic Logic*. Her main interests are: the logic of diagrams, visualization in mathematics, visual reasoning, Peirce’s logic, and more.

**Inspirational** **Early Career Researcher Lorenz Demey**

**Title: **From Aristotelian Diagrams to Logical Geometry

In this talk I will present a broad and accessible overview of the history of Aristotelian diagrams in general, and the research program of logical geometry in particular. Aristotelian diagrams are among the oldest and most well-known diagrams in logic: they include the square of opposition for syllogistics, but also many other, more complex diagrams for other logical systems. Next to their well-documented history in the areas of philosophy and logic, Aristotelian diagrams nowadays also enjoy many applications in other areas that deal with reasoning, such as linguistics, psychology, legal studies, artificial intelligence, etc. Over the past decade it has become increasingly clear that these diagrams can also fruitfully be studied as objects of independent logical, diagrammatical and philosophical interest. This has given rise to the burgeoning research program of logical geometry. On the logical-mathematical side, I will primarily focus on the ongoing development of an overarching typology of Aristotelian families and Boolean subtypes (based on combinatorial bitstring analysis). On the visual-diagrammatical side, I will discuss the crucial role of central symmetry in Aristotelian diagrams, and discuss their relationship with other well-known types of logical diagrams, such as Euler diagrams and Hasse diagrams. Finally, on the philosophical side, I will consider the fundamental question why Aristotelian diagrams are used so widely in the first place. Although they started out primarily as mnemonic devices in pedagogical contexts, I will argue that nowadays they primarily function as powerful heuristic devices, pointing us to unexpected parallels across time periods and across scientific disciplines.

**About Lorenz Demey:** Lorenz Demey (° 1986) is research professor in philosophical logic at KU Leuven. He studied philosophy, mathematics, logic and artificial intelligence at KU Leuven and Universiteit van Amsterdam (Institute for Logic, Language and Computation). He obtained his PhD in 2014, spent research stays at the universities of Oxford and Bochum, was appointed as assistant professor at KU Leuven in 2019, and promoted to associate professor in 2022. Demey’s work is supported by various grants and projects, including an ERC Starting Grant of the European Research Council. He currently (co-)supervises 10 PhD students and 4 postdoctoral researchers, and has already co-supervised one PhD student to completion. Demey’s research is primarily focused on logical geometry and the history of logic, and has a strong interdisciplinary orientation. He frequently collaborates with logicians, philosophers, classicists, historians, linguists, psychologists and computer scientists; his longstanding collaboration with the linguist Hans Smessaert has proved to be particularly fruitful. Demey’s research output over the past decade comprises over 60 research articles and 4 books, and has received substantial scientific recognition, such as the Research Council Award 2018 from KU Leuven, the Best Paper Award at Diagrams 2020 (co-authored paper with Smessaert and Atsushi Shimojima), and the Frans Van Cauwelaert Prize 2020 from the Royal Flemish Academy of Belgium (KVAB). Demey also greatly enjoys teaching and science popularization. He regularly teaches logic and epistemology at the faculties of philosophy and law at KU Leuven, and has taught an introductory course on logical geometry (together with Smessaert) at ESSLLI 2018. He frequently gives talks and interviews about logic and analytic philosophy for broad audiences (often high school students), for which he was awarded the KVAB Annual Science Outreach Prize in 2020.