A li'l paper I wrote in response to a question/conversation with Allen Hazen and Jeff Pelletier a couple of months ago went online today in the Journal Philosophical Logic: Natural Deduction for the Sheffer Stroke and Peirce’s Arrow (and any Other Truth-Functional Connective) (If you're not blessed with a Springer Link subscription, there's a preprint … Continue reading Natural Deduction for the Sheffer Stroke and Peirce’s Arrow
Author: rzach
Visiting Research Chair in Logic/HPS (2016/17)
Would you like to spend a semester or two in beautiful Calgary, Canada, during the 2016/17 academic year? The University of Calgary is pleased to offer the opportunity for a Fulbright Visiting Research Chair in Logic or the Philosophy of Science. The visiting researcher will be a part of the Department of Philosophy and collaborate … Continue reading Visiting Research Chair in Logic/HPS (2016/17)
Git for Philosophers (pt. 1)
What is Git? When software developers work on complex programming projects, they use something called a revision control system. A revision control system allows them to keep track of changes in their code -- it stores a history of changes, and allows them to quickly and easily take back ("revert") changes that turn out to … Continue reading Git for Philosophers (pt. 1)
Open Logic Project
A new open-source advanced logic text, announced earlier this week on the new blog: richardzach.org. Please update your links and subscriptions.

Introducing: The Open Logic Project
We've kept this on the down-low long enough, I think: together with Aldo Antonelli, Jeremy Avigad, Nicole Wyatt, and Audrey Yap, I've been working on an open source advanced logic textbook for a little while; Andy Arana and Gillian Russell are also on the editorial board. It's far from done; in fact the whole idea … Continue reading Introducing: The Open Logic Project
Why Scanlon Left Logic for Political Philosophy
T. M. Scanlon is one of the foremost moral and political philosophers alive. But he started as a logician, working with Benacerraf as an undergraduate at Princeton, Dummett during a Fulbright at Oxford, and Dreben for his Ph.D. at Harvard. His first two papers were: The Consistency of Number Theory Via Herbrand's Theorem, JSL 38 … Continue reading Why Scanlon Left Logic for Political Philosophy
Pen Maddy: Is Math Mysterious?
They ask, "Is there something mysterious about mathematics?" Among others, Pen Maddy answers. http://ideas.aeon.co/questions/is-there-something-mysterious-about-math
Eight Logicians Elected to the American Academy
The American Academy of Arts & of Sciences has announced its 2015 class of members. The recipients of this prestigious honor include eight logicians: Sanjeev Arora (Computer Science, Princeton University) works in complexity theory, and is especially known for his work on probabilistically checkable proofs. He previously won the Gödel Prize for his work on … Continue reading Eight Logicians Elected to the American Academy

Anita Burdman Feferman, 1927-2015
Anita Burdman Feferman, the noted biographer of Jean van Heijenoort and Alfred Tarski, died on April 9. She was the author of Politics, Logic, and Love: The Life of Jean van Heijenoort (Jones and Bartlett, 1993, reprinted as From Trotsky to Gödel, CRC Press, 200) and the co-author of Alfred Tarski: Life and Logic (CUP, 2004). … Continue reading Anita Burdman Feferman, 1927-2015

Finding Cheryl’s Birthday with DEMO
Following up on the Dynamic Epistemic Logic treatment of Cheryl's Birthday Puzzle, Malvin Gattinger (ILLC Amsterdam) has formalized the problem in DEMO_S5, a Dynamic Epistemic Logic model checker written in Haskell by Jan van Eijck (CWI Amsterdam and ILLC). The original DEMO system was described in: Jan van Eijck: "DEMO—a demo of epistemic modelling" In: Johan … Continue reading Finding Cheryl’s Birthday with DEMO

Mancosu on Frege and Direction
Remember the part in Frege's Grundlagen where he starts to talk about abstraction by talking about the direction of lines? Two lines have the same direction if and only if they are parallel; this gives an identity criterion for directions of lines. Ever wondered why Frege starts bringing in geometry? What the historical context and … Continue reading Mancosu on Frege and Direction
Ask Your Librarian to Subscribe to PhilPapers!
PhilPapers now has almost 1.75 million entries. Like the Stanford Encyclopedia, the project is non-profit and largely run by volunteers. In order to be sustainable, they do need funding. And like the Stanford Encyclopedia, they are asking for our help: so ask your library to subscribe! The merger of Philosophy Research Index into PhilPapers has … Continue reading Ask Your Librarian to Subscribe to PhilPapers!
Logicians Yap, Kooi Explain Viral Birthday Logic Puzzle
You've probably seen the "birthday logic puzzle" that's gone viral in the past few days. If you haven't, you might want to try to solve it yourself. Here it is: Two dynamic epistemic logicians, Audrey Yap (UVic) and Barteld Kooi (Groningen) explained the solution (and how to get it) on facebook. "Dynamic" here modifies "epistemic", … Continue reading Logicians Yap, Kooi Explain Viral Birthday Logic Puzzle
Logic without Borders: Essays in Honor of Jouko Väänänen
A Festschrift for Jouko Väänänen's 60th birthday is now out with de Gruyter, edited by Åsa Hirvonen, Juha Kontinen, Roman Kossak, and Andrés Villaveces: In recent years, mathematical logic has developed in many directions, the initial unity of its subject matter giving way to a myriad of seemingly unrelated areas. The articles collected here, which … Continue reading Logic without Borders: Essays in Honor of Jouko Väänänen
Moshe Vardi Elected Fellow of SIAM
SIAM just announced its list of Fellows for 2015, and it includes Moshe Vardi. The citation reads: Moshe Y. Vardi is Karen Ostrum George Distinguished Service Professor in Computational Engineering and Director of the Ken Kennedy Institute for Information Technology at Rice University. He is being recognized for contributions to the development of logic as … Continue reading Moshe Vardi Elected Fellow of SIAM

Quine’s Paradox and Gödel’s Theorem
It's a commonplace to compare Gödel's theorem to the liar paradox: The sentence This sentence is not true. is neither true nor false. Switch out "provable" for "true" and you get This sentence is not provable. and, modulo some technical stuff, this sentence is then neither provable nor refutable. But of course the "modulo some … Continue reading Quine’s Paradox and Gödel’s Theorem
My Sessions at the Pacific
I'm organizing two sessions at the Pacific APA; please join me there! Thursday, April 2, morning, 9-noon: 4A Book Symposium: Greg Frost-Arnold, Carnap, Tarski, and Quine at Harvard: Conversations on Logic, Mathematics, and Science Speakers: Richard Creath (Arizona State University) Gary Ebbs (Indiana University Bloomington) Greg Lavers (Concordia University) Greg Frost-Arnold (Hobart and William Smith … Continue reading My Sessions at the Pacific
Falso
A computer-verified proof of ⊥: https://github.com/clarus/falso (h/t Byron Cook)
Petr Vopěnka, 1935-2015
The Czech logician and set theorist Petr Vopěnka has died. He has made significant contributions to classical set theory and founded alternative set theory. You may find this 2006 documentary by Andrea Slováková interesting (Czech with English subtitles). Obituaries: Prague Monitor
Academic Genealogy Graphed
The Mathematics Genealogy project is a huge database of mathematicians, where and when they got their degrees, and who their advisors were. (There's also a wiki-based Philosophy Genealogy.) Nice pastime when the polar vortex keeps you from leaving the house: find famous people in your academic family tree. If you're in the Mathematics Genealogy, you … Continue reading Academic Genealogy Graphed