My research in the philosophy of mind is guided by the question of what belief is and how it differs from other cognitive attitudes, especially from imaginings. In my dissertation, I approach this question by considering the topic of delusions, and by offering a new critical perspective on the received view that delusions are beliefs. A recurring theme in my historical work is the question of what role canonization plays for the treatment of ideas, and how to better integrate underrepresented prespectives and unorthodox views into our historiography. Some of the topics I have recently written about here include the role of diagrammtic reasoning in Euclid‘s Elements and its reception since antiquity, and Christine Ladd-Franklin‘s contributions to logic and mathematics. I am also involved in a joint project that argues for a reconsideration of Hegel’s impact on post-Civil War educational thought in the United States beyond John Dewey’s contribution.

Philosophy of Mind and of Cognitive Science: The Nature of Delusions

In my dissertation, Delusions as Imaginings, I argue that the doxastic account of delusions, which describes delusions as irrational or otherwise deficient beliefs, faces various challenges, such as that it cannot explain what it is that makes delusions pathological. It also fails to sufficiently distinguish delusions from related phenomena, for instance from beliefs in conspiracy theories or propaganda. Instead, I argue, amending Currie and others’ (e.g., Currie 2000; Currie and Ravenscroft 2002) earlier proposal, that delusions are states of the imagination.

I ultimately object to Currie’s characterization of delusions as involving a meta-cognitive mistake. Instead, I present an argument that is structured as an Inference to the Best Explanation and that argues that an involvement of the imagination is constitutive of delusions: Given our current best evidence concerning both the epistemic surface properties of delusions and their likely underlying causal mechanisms, describing delusions as imaginings fares better than the doxastic alternatives. Among other things, I discuss the recent application of the prediction error account of aberrant perception to delusions. I also discuss the recent hypothesis in the philosophy of psychiatry that a failure to deactivate the Default Mode Network may be involved in the etiology of delusions and could even be used as a marker of delusional states in schizophrenia (Landin-Romero et al. 2015). Since the Default Mode Network is typically involved in phenomena such as mind-wandering, day-dreaming, dreaming, and imaginative states more generally, I argue that we should conclude that delusions lie on a continuum with ordinary mental states, but in contrast to Bortolotti I argue that they lie on a continuum with other states of the imagination, instead of with doxastic states.

History of Philosophy: Euclid, Ladd-Franklin, Hegel

My work in the history and philosophy of logic and mathematics is guided by a focus on the question of what role canonization plays for the treatment of ideas in the history of philosophy–namely, first, in the context of the role of diagrammatic reasoning in Euclid’s Elements, and second of Christine Ladd-Franklin’s contributions to logic and mathematics. In both cases, we find a marked imbalance in the treatment by the canon. While the Euclidean diagrams have received ample attention throughout the centuries, I will yet identify a tendency to understand mathematical practice in a particular manner, and within a particular tradition–at the expense of other viewpoints. Meanwhile, Christine-Ladd Franklin’s contribution to the disciplines of psychology, logic, mathematics, and also philosophy, suffered a different imbalance: It has commonly been neglected. 

Diagrammatic Reasoning in Euclid

My work on the reception of Euclid focuses on a recent proposal to understand the Euclidean demonstration in a way that notably differs from its traditional interpretation. Kenneth Manders, Marco Panza, Danielle Macbeth and others have recently argued that the Euclidean demonstration—as the paradigm of ancient mathematical practice—should not be understood as an axiomatic system, but instead as a system of natural deduction. According to this new reading, Euclid’s procedure does not employ Common Notions, Postulates, and Definitions as premises on the basis of which theorems are proven, but instead provides the rules of reasoning. I have recently presented this material at conferences, namely in January 2022 at the University of Paderborn and in April 2022 at UNILOG in Crete. A German version of the paper is forthcoming in the Siegener Siegener Beiträge zur Geschichte und Philosophie der Mathematik, Band 15 (expected 2023). 

The main goal in the coming years is to fill in a more complete historical account of the understanding of the axioms that we find in Manders and others’ work. I am planning to begin by considering Poincaré’s and Schröder’s understanding of the axioms as hidden definitions, and furthermore Hilbert’s understanding of axiomatic systems as ordering systems that justify axioms internally, instead of primarily in terms of rules of inference, and lastly Pieri’s understanding of elementary geometry as hypothetico-deductive. I will argue that while these earlier views concur that the axioms do not provide the starting points of reasoning, they possess certain explanatory advantages over the recent reading, most notably in that they can accommodate variation among mathematical systems, which Euclid’s demonstrations in the reading as a system of natural deduction do not. 

Christine-Ladd Franklin’s “Algebra of Logic”, and the “Antilogism”

Another historical strand of research I will continue to pursue in the coming years is studying Christine-Ladd Franklin’s contribution to the history of logic and mathematics, which has long been neglected at the expense of her collaborator Peirce. I try to show that we should reassess Ladd-Franklin’s impact on the tradition of pragmatist approaches to semantics: Some (such as Susan Russinoff) have even argued that Ladd-Franklin’s work in fact provides “the most significant advance in syllogistic logic in two thousand years” (Russinoff 1999, 451). 

I have recently presented Ladd-Franklin’s research program at a workshop on “Female Logicians” at the University of Hagen in January 2022 and at a a conference on “Logic of Judgement” also at Hagen in October 2022. I argued that Ladd-Franklin’s conception of the “antilogism” foreshadowed the recently suggested reorientation towards an understanding of semantics as based on incompatibility rather than truth. A paper on “Christine Ladd-Franklin as a Precursor to Incompatibility Semantics“, is currently under review for History and Philosophy of Logic, Volume 43, Issue 1.

Hegel’s Impact on post-Civil War Educational Thought in the United States

My last historical research project lies outside the philosophy of mathematics and logic and concerns the history and philosophy of education in the United States. Since 2019, I have been engaged in a research project with David Beisecker and Joe Ervin (both UNLV) that argues for a reconsideration of Hegel’s impact on post-Civil War educational thought in the United States beyond John Dewey’s contribution. We claim that Hegelianism in America after the war exceeded its Prussian source in focusing on the question of how to provide for citizens’ freedom in the new democracy, and on questions of institutional implementation, particularly in the context of education. Our work has been focused both on questions of how to build educational institutions in a radically changing society, namely the emerging United States of America (Ervin et al. 2021; Özel et al. 2021). But we are currently also looking into the darker side of this tradition, such as the role that Hegelian ideas played in constructing and defending the Indian Boarding School system. We presented our material at the Annual Meeting of the Philosophy of Education Society, and I also presented it to a German audience at Paderborn University in July 2022.