2025 ii: Editorial Note

Saturday, Oct 11, 2025

The beauty of the ILLC, and what makes it such a special place, is the diversity of thought. Students and professors from so many different backgrounds and intellectual interests, sharing ideas and …

Construct Colimits in a Topos Using Elementary Methods

Monday, Aug 4, 2025

An elementary topos is a category with finite limits, exponentials, and a subobject classifier $t:1\rightarrow\Omega$. We do not know from the definition that a topos has colimits. Surely we have …

Engineering Sexual Orientation

Saturday, Aug 9, 2025

Perhaps Lady Gaga was right - sexual orientation is not our choice: baby, we were born this way. This conception has, after all, done much for the mainstream acceptance of certain queer identities. …

Ingredients and Logic - Is putting pineapple on pizza rational?

Monday, Aug 4, 2025

A MoL dinner

After a week of intense study, four MoL students - $E$, $M$, $S$, and $J$ - met at a renowned Amsterdam pizzeria. The restaurant offered a special deal:

Any group of students …

Interview with Prof. Catarina Dutilh Novaes

Monday, Feb 16, 2026

For the first The Illogician MoL alumni interview series, meet Prof. Catarina Dutilh Novaes (VU). Catarina is a philosopher who moves effortlessly from medieval manuscripts to modern logic, asking big …

Logic Dating Profiles

Monday, Feb 16, 2026

Intuitionistic type

I take things constructively

Topos type

Looking for someone who accepts my internal logic

Euclidean Frame type

All my exes know each other

Reflexive Frame type

I am very self-aware …

Mathematical Structures in Programming Languages

Monday, Aug 4, 2025

If you enjoyed the Mathematical Structures in Logic course from last semester, you are going to love Nick’s rebranding for the new year: Mathematical Structures in Programming Languages! …

Mathematicians, list your ingredients!

Saturday, Aug 9, 2025

A wise friend of mine once compared being a constructivist to being a vegetarian: even if you are convinced it is the right choice, it is hard to fully commit to it in practice. As a vegetarian and a …

Merkle Puzzles: How to tell a secret

Saturday, Aug 9, 2025

It is Christmas 1974, in the midst of the cold war, and intelligence officer Alice is trying to reach her asset Bob, who is undercover in Budapest, from her apartment in Amsterdam. She knows Bob has …

Proving Everything While Revealing Nothing: An Introduction to Zero-Knowledge Proofs

Monday, Feb 16, 2026

Introduction

It’s 2 AM and you’re locked out of your email account. The system asks you to prove your identity by entering your password. You type it in, hit enter, and hope the server …

Regularity Properties of the Reals and the Axiom of Choice

Saturday, Aug 9, 2025

In this article, we aim to give an introduction to the set theoretic study (Jech 2003) of relation between regularity properties of the reals and the Axiom of Choice. Broadly conceived, regularity …

Rotating Shapes: The long(est) line

Monday, Aug 4, 2025

Rotating Shapes: Two Möbius make a Klein

Monday, Feb 16, 2026

Most people know that if you take a long piece of paper, twist one end 180 degrees and then glue it to the other one, you get a shape with only one side and edge. Indeed, if you have never seen this, …

The Axiom of Bad Choice and its Equivalents

Monday, Feb 16, 2026

Translator’s note

This paper, unpublished on any known mathematical outlet at the time, dates back to March 1946, and was found in a parcel in the Beth Library, in the ILLC common room, in the …

The Illogicians' Conversation

Monday, Aug 4, 2025

In this crazy discussion, each speech turn contains a semantically deviant or infelicitous utterance. Can you guess what is causing each oddity?

1. B: Hi Gottlob! In what way are you doing?
2. G: Yes! What …

The Logico-Empirical Foundations of Medieval Witchcraft Ascertainment: A Pythonian Analysis

Monday, Aug 4, 2025

This paper examines the application of proto-scientific methodology in the well-documented medieval inquiry portrayed in Monty Python and the Holy Grail, specifically the “She’s a …

The Story of Moscow's Methodological Circle

Monday, Feb 16, 2026

The Moscow Methodological Circle was a philosophical, cultural, and political phenomenon which took part in the rebirth of the study of logic in the USSR, vastly influenced Soviet economy, and still …

Too much information? The usefulness of talking redundantly

Monday, Feb 16, 2026

Suppose you and your favourite MoL-student are procrastinating on your homework assignment (very unrealistic, I know). You decide to play a game – not a very hard one, because your assignment is …

When *if* comes after *then*

Monday, Aug 4, 2025

Suppose you want to tell someone that you believe that the first edition of The Illogician will be a success, provided that the articles in it are well written. You could convey this message in the …