Greg Restall
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consequently.hcommons.social.ap.brid.gy
Greg Restall
@consequently.hcommons.social.ap.brid.gy
190 followers 2 following 66 posts
Philosopher and logician, from Australia, now based at the University of St Andrews in Scotland.

I like thinking about—and helping other people think […]

[bridged from https://hcommons.social/@consequently on the fediverse by https://fed.brid.gy/ ]
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consequently.hcommons.social.ap.brid.gy
Tomorrow evening, I get to talk to the Philosophy Society students about what I do (as a philosopher/logician) and why I do it. I’ll be interested to discover what the students make of it and where the conversation goes.

I love the poster they made for the […]

[Original post on hcommons.social]
A red-and-white poster advertising a St Andrews Philosophy Society talk: Greg Restall “Why Logic Matters for Philosophy, and Philosophy Matters for Logic”. A stylised human figure (in white) holding an umbrella, protects themselves from a torrent of logical symbols, falling from a heavy white cloud.
November 17, 2025 at 10:14 AM
consequently.hcommons.social.ap.brid.gy
Tomorrow, I get to give the last of my three talks on inferentialism. It’s time to buckle up your λs, and join in the search for some unicorns…

https://consequently.org/presentation/2025/whl-a/

#prooftheory #semantics #linguistics
Some pages of a handout for a talk on intensional semantics and inferentialism. A derivation tree for the classic sentence “John seeks a unicorn” in Daniel Gallin’s two-sorted type theory Ty2 is in view, along with an obscured picture of the linguist Barbara Partee.
October 7, 2025 at 4:33 PM
consequently.hcommons.social.ap.brid.gy
I’m doing my part to help those wandering the hallways in Edgecliffe to know where to find the relevant exit…
A photo of two doorways, the one on the left (labelled “Seminar Room”) largely obscured, and the one on the right, labelled as the office of “Prof. Greg Restall.” Between them, a print of a photo, displaying a large roadsign saying “Logic Centre, This Exit”. Prof. Restall’s office door is ajar. On it are various A4 posters of book covers and flyers advertising talks and conferences.
October 1, 2025 at 9:17 AM
consequently.hcommons.social.ap.brid.gy
The next item on my docket is preparing my talks for the 2025 Wendy Huang Lectures, which I’ll be giving in Taiwan next month. To prepare, I’m giving the presentations a test run with the home crowd, for the next three Wednesdays.

https://consequently.org/presentation/2025/whl-a/
An A4 page, the first page of a multi-page handout for the first Wendy Huang Lecture, entitled “Inferentialism for Everyone”.
September 22, 2025 at 11:27 AM
consequently.hcommons.social.ap.brid.gy
A man seeks an iced black coffee, while John seeks a unicorn.

#eh9 #Coffee #dundee #montaguesemantics
A clear glass filled with cold black coffee, ice, and containing a green straw, to the right of an iPad, with two windows open, one a Vim session, editing a latex file, and the other, the pdf of the compiled output. A parse tree of the sentence “John seeks a unicorn” is visible in both views.
July 11, 2025 at 1:07 PM
consequently.hcommons.social.ap.brid.gy
The anarchist type theorists are in evidence along Riverside Walk in Dundee.

#typetheory #dundee
A rectangular black sticker, with yellow writing, saying “the only good system is a type system” with a centred lower case lambda in a circle.
July 11, 2025 at 12:05 PM
consequently.hcommons.social.ap.brid.gy
Charles Travis, logical pluralist.

This is an extract from his *Unshadowed Thought,* Harvard University Press, 2000.
It is a familiar idea that (to be) a good inference is (to be) truth preserving: where what S stated is inferred from what given other statements did, the inference is good if the truth of those others guarantees the truth of S—wherever they were true, S would be. One might think of the laws of truth as deciding when that is so. Since the notion 'guarantee,’ and, likewise, the notion 'wherever,’ are open to negotiation, perhaps we should say that this characterizes a family of notions of good inference (corresponding, perhaps, to a family of notions of entailment).
July 10, 2025 at 2:28 PM
consequently.hcommons.social.ap.brid.gy
Aldo and I served on the editorial board of the Journal of Philosophical Logic, and then the Review of Symbolic Logic. I learned a great deal from him, and from my co-editors, and it will be good to remember him with friends, old and new.
Three men, seated on a bench, in front of a brick wall. From left to right, Albert Visser, in a blue jacket over yellow shirt and trousers, Aldo Antonelli, in a grey shirt and jeans, holding a camera, and to the right, Greg Restall, in a paisley shirt and dark jeans.
June 16, 2025 at 2:00 PM
consequently.hcommons.social.ap.brid.gy
I seem to be back in Glasgow, with its refreshing attitude to authority.
Wellington's statue, adorned with a traffic cone (actually three) outside the Gallery of Modern Art.
June 8, 2025 at 5:13 PM
consequently.hcommons.social.ap.brid.gy
Coming up today, the first outing of my talk on Tim Williamson’s philosophical methodology and what we can learn from it.

(Featuring order types, natural deduction proofs, epistemic logic, sudoku puzzles, Nuel Belnap on pre-semantics, and more. What’s not to […]

[Original post on hcommons.social]
A pile of stapled handouts, with the title “Must Do “Must Do Better” Better”
June 5, 2025 at 8:00 AM
consequently.hcommons.social.ap.brid.gy
I'm running the risk of distracting my audience by including a sudoku puzzle in a handout for an upcoming talk, to make a point about epistemic logic and the semantics of propositional attitude ascriptions.
A sudoku puzzle with a blank square highlighted.
May 25, 2025 at 7:51 PM
consequently.hcommons.social.ap.brid.gy
Finding myself on this selection of accepted papers for TYPES 2025 gives me the “Big Bird turning up to a meeting to which he isn’t qualified” vibe, but regardless, I’m really looking forward to hanging out in Glasgow next month and learning lots of type […]

[Original post on hcommons.social]
Big Bird (a Sesame Street character that is a large, yellow bird) sitting at one end of a conference table, drawing with crayons on a pad of paper, surrounded by a group of young human (not bird) comedy writers, all with laptops open in front of them.
May 8, 2025 at 12:42 PM
consequently.hcommons.social.ap.brid.gy
I’m in Amsterdam, about to give a talk about proof theory for modal predicate logic at the ILLC, the home base of the modal industrial complex. I have no idea how this is going to go over, but it should be a fun ride, however it turns out […]

[Original post on hcommons.social]
A view across a broad canal in central Amsterdam, with canal boats moored to the right, and a series of terrace buildings on view behind them. A smaller Amsterdam canal viewed from a brick bridge overpass.
April 10, 2025 at 10:55 AM
consequently.hcommons.social.ap.brid.gy
Last night’s performance, by the Dunedin Consort—of a mixed programme of choral music from the renaissance to the present day, on Lenten themes—was very special indeed. I knew some of the repertoire (I was familiar with the Lassus, and had heard the Poulenc […]

[Original post on hcommons.social]
A view of a church interior, toward an ornate pulpit, in front of a large stained glass window. Dundee Parish Church of St Mary’s.
March 30, 2025 at 4:00 PM
consequently.hcommons.social.ap.brid.gy
It’s good to be back home in Scotland, especially now that the sun is still decently above the horizon at 4:30pm.
The sun peeking through some bare tree branches, above a grassy park.
March 19, 2025 at 5:16 PM
consequently.hcommons.social.ap.brid.gy
I'm glad to have space to get to writing, and the first writing project of my sabbatical has reached first-draft stage. If you're interested in modal logic, proof theory, and the metaphysics of contingent existence, have I got the paper for you! […]

[Original post on hcommons.social]
Structural rules, term rules and defining rules in a hypersequent calculus for a first-order modal logic.
January 20, 2025 at 2:52 PM
consequently.hcommons.social.ap.brid.gy
It’s a cloudy and cold Tuesday, and I’m inside writing about refinement.

At least I *think* I understand what I’m doing a bit better than Mark S and his team of macrodata refiners do.

(That’s an inappropriate #Severance, #prooftheory #ModalLogic and […]

[Original post on hcommons.social]
A screen containing a series of clauses in the proof theory of quantified modal logic, above a mechanical keyboard with dark blue and light blue keycaps.
January 7, 2025 at 1:11 PM
consequently.hcommons.social.ap.brid.gy
This morning, one of my hardworking intermediate logic students (prepping for her exam next week), came to me with a query about how to prove the constructively invalid quantifier negation inference (from ∀x(A(x)∨B(x)) to ∀xA(x)∨∃xB(x)) in natural […]

[Original post on hcommons.social]
A natural deduction proof from ∀x(A(x)∨B(x)) to ∀xA(x)∨∃xB(x) in Gentzen/Prawitz natural deduction, with Double Negation Elimination. A natural deduction proof from ∀x(A(x)∨B(x)) to ∀xA(x)∨∃xB(x) in Gentzen/Prawitz natural deduction with alternatives.
December 11, 2024 at 9:49 AM
consequently.hcommons.social.ap.brid.gy
Graham Priest is in the house, playing some of the greatest hits, alongside some of his newest
material.

#philosophy #paradox #metaphysics #logic
An older bearded male white man (Prof. Graham Priest) standing on front of a digital projection, upon which a diagram (illustrating the inclosure schema) is projected.
November 25, 2024 at 7:10 PM
consequently.hcommons.social.ap.brid.gy
Thanks to Norbert and Edi for organising a focused, tight, but relaxed and friendly one-day workshop on Free Logic. I enjoyed each talk and the many discussions between talks and afterward. That was such a fun day, and I’ve got a lot to think about […]

[Original post on hcommons.social]
A projected handwritten PDF slide, entitled “Defining Quantifiers”
November 16, 2024 at 10:00 PM