Do objectively correct solutions to ethical dilemmas exist? Or is ethics always a matter of your opinion against my opinion? How do you know what to do? What kind of thing is ethics anyway? Can you be an expert in ethics?

The research programme Probability Theory focuses on probability theory and on operations research.

Many important topics in computer science, such as the correctness of software, the efficiency of algorithms and the modeling of complicated systems, depend on sound theoretical underpinnings. In the Theory group, we study these fundamental building blocks and develop verification methods to prove system…

Many important topics in computer science, such as the correctness of software, the efficiency of algorithms and the modeling of complicated systems, depend on sound theoretical underpinnings. In the Theory group, we study these fundamental building blocks and develop verification methods to prove system…

The research of the Algebra, Geometry and Number Theory programme ranges from fundamental mathematical theory to algorithms and applications.

This book addresses the definition of history and how people are influenced by it.

Promotor: H.W. Lenstra, Jr., Co-promotor: B. de Smit

This dissertation is a collection of four research articles devoted to the study of Kummer theory for commutative algebraic groups.

This book addresses the definition of history and how people are influenced by it.

Promotor: S.J. Edixhoven, Co-promotor: R.S. de Jong

In analogy to mathematical proofs, the goal of a proof system is for a prover to convince a verifier of the correctness of a claim.

Subproject of

The research of the Algebra, Geometry and Number Theory cluster tries to bridge the gap between abstract theory and the world of algorithms and applications.

In this thesis we examine certain phenomena in symplectic topology which are related to the theory of isolated singularities.

On the brink of war, what influences decision makers to attack another country? Using innovative theoretical angles, Femke E. Bakker explores whether the basic assumptions of democratic peace theory are indeed correct. She stresses the microfoundations of conflict, questioning the assumptions on…

Sentencing is becoming increasingly complex for the courts. Legal scholars and criminologists from Leiden document the process of sentencing in the Netherlands. They use this knowledge to advise legislators and those who implement this legislation on how to make sentencing more consistent and effect…

Edited by linguists Jenny Audring (Leiden University) and Francesca Masini (University of Bologna), this is a unique handbook with a focus on morphology theories rather than morphological data. It covers a wide array of morphological theories, from traditional twentieth century models to current theoretical…

The thesis mainly contributes to the characterization of Majorana fermions as they appear in the Condensed Matter context.

The Death of Archaeological Theory, edited by John Bintliff and Mark Pearce, addresses the provocative subject of whether it is time to discount the burden of somewhat dogmatic theory and ideology that has built up over the last 25 years.

Changing individual and collective behavior is critical to addressing the climate and ecological crisis. Environmental psychology is thus well-positioned to contribute knowledge to guide impactful climate action.

Truth is stranger than fiction. In 1997 Juan Maldaceña discovered a remarkable dictionary that translates equation for equation the physics of black holes in string theory into the more conventional physics of quantum mechanics of interacting particles. The remarkable possibility exists that…

Explore the MSc in Political Theory: Legitimacy and Justice at Leiden University. Dive into core themes like justice and legitimacy, study classical and modern political theory, and sharpen your analytical and philosophical skills.

This MA explores contemporary literature and culture—art, film, pop music—through critical and theoretical lenses, including feminist theory, phenomenology, and ecocriticism. Key themes include diversity, interculturality, popular culture, and the intersection of culture, politics, and justice.

The focus of Jan Zaanen's theoretical physics research was the nature of macroscopic matter that is in one or the other way still in the grip of quantum physics.

Are you thinking about studying Cultural Analysis: Literature and Theory? Learn more and watch the introduction video.

Imitation is, perhaps more than ever, constitutive of human originality.

My PhD research is devoted to studies of the conjectural cluster-algebraic symmetry in the theory of topological string, which is the simplest, however already non-trivial sector in the theory of string.

The Summer School on International Humanitarian Law is designed by the Grotius Centre Kalshoven-Gieskes Forum on International Humanitarian Law.

Promotor: K.E. Schalm, Co-promotor: S.S. Lee

This six-weeks online course delves into the research behind terrorism as it unpacks the assumptions and impacts of both terrorism and counterterrorism.

We study the structure, dynamics and physics of complex networks emerging from the intricate interconnectedness of the constituents of large systems.

Get in touch about the MSc Political Theory: Legitimacy and Justice at Leiden University — contact study advisers, the student ambassador, or support services for programme and application questions.

Western thought has often dismissed shadows as fictional, but what if fictions reveal original truths?

The focus of our theoretical research is understanding the behaviour of soft condensed matter, physical matter which is deformed or structurally altered by thermal fluctuations or small stresses.

Promotor: J. Zaanen

On the 28th of September Go Hirasawa successfully defended a doctoral thesis and graduated.

This study looks at the question of how and at what level students in primary teacher education can integrate theory and practice, and how the organisation of their learning environment, focusing especially on mathematics and pedagogy, can contribute to that.

Explore the programme of the MSc Political Theory: Legitimacy and Justice at Leiden University — focusing on core political philosophy themes, in-depth theory, methods, elective seminars, and a thesis or internship track.

Explore the structure of the MSc Political Theory: Legitimacy and Justice at Leiden University, including core courses, electives, method training, thesis or internship, and small‑group seminars.

Effective policy-making requires understanding what truly causes a problem. Only then can policymakers develop targeted interventions that achieve desired outcomes.

Chat with a current MSc Political Theory: Legitimacy and Justice student at Leiden University to get firsthand insights on the programme, student life, and study experience.

Organized by the Grotius Centre for International Legal Studies, this programme enables students and professionals from all over the world to engage in discussions on the prospects and challenges of international criminal justice.

Humans can see the world through the eyes of other humans and imagine what they know, want, and intend. This competence is known as Theory of Mind.

The terms ‘social’ , ‘collective’ or ‘public’ memory, are often contrasted with ‘private’, ‘individual’ or ‘personal’ memory. All these terms derive from a fairly new and interdisciplinary scholarly field that is often referred to as ‘memory studies’, and that according to some critics has developed…

Systems with local constraints is a new finding in recent researches on complex systems. The heterogeneous spatial interactions and the temporal dependencies among those numerous units make it difficult to describe by traditional statistical physics.

In this work we describe three methods to improve the performance of Quantum Field Theory calculations.

Following their application to system biological models, control theory techniques have further potential to aid in the understanding and application of quantitative systems pharmacology models.