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2nd Semester 2021/22: Philosophy of Logic: Logical Pluralism

Robert Passmann

Every student in the Master of Logic knows that there are many different logical systems: classical logic, intuitionistic logic, substructural, modal and higher-order logics, among many others. Some of these systems are different in virtue of vocabulary. For example, (classical) modal logics add modal operators to classical logics. Others use the same vocabulary but differ in terms of validity: the law of excluded middle is valid in classical logic but not in intuitionistic logic.

Given so many different systems, we can wonder whether it makes sense to ask which of these are correct? If so, (how) can we determine which logic(s) are correct? One position in the philosophy of logic is the so-called logical pluralism claiming that there are at least two different but equally correct logics. (Of course, this requires some spelling out — it wouldn’t seem proper pluralism to hold that both classical first-order and classical propositional logic are correct.)

In this project, we will examine the debate surrounding logical pluralism and related positions. Depending on students’ interest, we may consider topics such as the normativity of logic, meta-logical ramifications, logical nihilism, anti-exceptionalism about logic, and so forth.

The goal of this project is for each student to write a research proposal related to logical pluralism (which could, for example, form the basis of a Master’s thesis).

This project is designed for a limited number of no more than 10 participants. The precise format of the project will depend on the actual number of participants. There will be some lectures, student-led seminars to present and discuss papers, individual supervisions and students presenting their own work.

The main prerequisite is an interest in the philosophy of logic, and some background knowledge in logic will also be helpful. If you doubt whether you should attend, please get in touch.


To pass this project, students will be expected to (1) actively participate during meetings, (2) give a presentation and host a discussion, (3) hand in a research proposal at the end.


For some preliminary reading, consider: