## “My heart in hiding/Stirred for a bird”

Photo from BBC website

When we lived in Aberystwyth, long since, there was only a handful of pairs of red kites left in the whole of Britain, living in the remote mid-Wales hills. But we would see kites occasionally gliding down the Ystwyth valley, to scavenge on the town tip next to the sea. The birds are now much more common in Wales, and have been re-introduced into various parts of England too with great success. But it was so surprising, the sheer delight to be driving out to a pub near Cambridge along a back way, turning a slight bend in the road, and — not a dozen yards from the car — a kite was swooping to the grass verge, grabbed its lunch, and magisterially flew slowly on.

How stirring such moments still are.

## The Pavel Haas Quartet at the Wigmore Hall

Another extraordinary concert from the Pavel Haas Quartet last night.

They began with Webern’s Fünf Sätze of 1909 – extremely condensed, emotionally unsettling music, which for me works better in a live performance than it can ever do listening to a recording. Certainly I have never got anywhere as much out of this Webern, as from this characteristically intense but totally controlled performance from the PHQ.

Next, the Shostakovich String Quartet, No. 2. Again, this is unsettling music, emotionally torn and veering from dissonance (even violence — and a resulting broken cello string) to the simply melodic and back.  Compared with the couple of recordings I know best, this again was extraordinarily intense playing last night.

Reviewing a recent DVD of Schubert quartets by Cuarteto Casals, Michael Tanner remarks in passing, “One always speculates – at least I do – about the dynamics, artistic and personal, of string quartet performers”. I find I speculate too. Was it just my romantic imagination, or at the centre of the slow movement of the Shostakovich, when the first violin has a particularly yearning melody set against the background of chords from the others, didn’t Veronica Jarůšková play directly to her husband and the father of their small child, the cellist Peter Jarůšek? It was difficult not to feel that.

After the  interval, the PHQ were joined by the young Dutch cellist Harriet Krijgh for Schubert’s  String Quintet. I think this was the first time that they have performed the piece together in a concert: so the first thing to say is that the ensemble, the stylistic unity, between the five of them was somewhere between superb and miraculous. And as for the interpretation, it is as you would have expected from the PHQ’s award-winning CD (with Danjulo Ishizaka). There was again  an overarching sense of the piece as a whole (so not at all one of those performances where the last two movements come as a disappointing let-down after the extraordinary heights of the first two). There was a particularly driven and emotionally taut third movement, so good that it drew premature applause. But, as always in great performances, the slow movement was transcendental: when it finished, the audience sat in total silence, not a murmur, not a rustle, not a cough.

If I am ever again present at a performance of the Quintet as good, I will count myself blessed.

## How do you like your metavariables?

Ok, logic people: it’s time to vote on a Grave Matter of Great Pedagogic Import!

So here I am, revising my intro logic book — which, recall, is intended for first year philosophers. I try to get things fairly precise, at least when we get down to formal business after the initial informal faffing around, but I  also aim to keep things unscary.

I’m still a bit torn about what to use as metalinguistic variables.

In the first edition of my book, I use a sans serif font for wffs in the formal languages, as in: $\mathsf{(P \lor Q)}$,  $\mathsf{\forall x(Fx \to Gx)}$.

Then I use serif italic for metavariables, e.g. as in ‘A’, ‘Fn’.  Though on the board in class, some years I’d actually use Greek letters for metavariables.

• Pro using italics: Familiar italic type  makes the book look rather less mathematical, rather less daunting (most philosophers are neither classicists nor mathematicians — so initially $\varphi(\xi)$ is about as friendly as ‘squiggle squoggle’).
• Pro using Greek: It’s the convention in more advanced texts so you might as well get used to it straight away. And for lecturers writing on the board, and for students taking notes, keeping track in your handwriting of ‘ordinary letters’ (for formal languages) vs Greek letters (metalinguistic) is much easier than trying to mark the distinction between e.g. upright and sloping letters.

In writing the first edition, friendliness-on-the-printed-page was the winning consideration. I still lean in that direction. But I’m interested to know what you think. So here is a poll (vote thinking of the interests of likely readers of an intro text!).

Greek letters for metavariables for beginning logic, or italic letters?

View Results

By all means add further thoughts in the comments below, as obviously this is a Very Serious Issue.

Posted in This and that | 8 Comments

## Munich conferences

I guess my conference-going days are past. But if I were full of youthful zip and enthusiasm, then the conferences run by the Munich Centre for Mathematical Philosophy would be terrifically appealing.

There’s one on Mathematical Structuralism which starts in a couple of weeks (talks should later appear on Youtube). And there is one in January on Model Theory: Philosophy, Mathematics and Language. I guess most readers of this blog with interests in that area will already know about this upcoming conference (for which there is a Call for Papers, whose deadline isn’t yet past). But I’m linking here, just in case you didn’t know about it.

## A little light medieval logic?

There is a new Cambridge Companion to Medieval Logic just out, edited by Catarina Dutilh Novaes and Stephen Read (all praise, by the way, to CUP for continuing to price the paperbacks of books like this so very reasonably).

The Companion is divided into two parts. The first, ‘Periods and Traditions’, has seven historical essays with titles like ‘Arabic Logic up to Avicenna’ and ‘Logic in the Latin Thirteenth Century’. The second part, ‘Themes’, has eight essays on topics like ‘Propositions: their Meaning and Truth’, ‘Sophisms and Insolubles’ and  ‘Consequence’.

Having dipped in and out, skimmed here and there, I’m not sure this is quite the book for me: but your mileage, as they say, may very well vary. As with much writing on the history of philosophy/history of logic, it will depend whether or not your interest is indeed primarily  historical. A lot of obscure-to-me figures get name-checked, without inspiring much inclination to find out more. If your attitude like mine is rather ahistorical,  if you are hoping to look to the medievals for some good logical ideas either missed or not well developed in current debates, then this is probably not quite the book for you. Certainly, given my ahistorical interests (OK, I’m a philistine), I would have welcomed a book which said quite a bit more about quite a  bit less.

For example, we are told on p. 317 that the view that from an impossible proposition anything follows “eventually … prevailed”. But we don’t get to know why, or what the contending considerations were. In the same chapter on consequence we are told that Buridan “subsumes under a broader notion of consequence” both, as we would put it,  $A \to B$ and $A \therefore B$. Since we tell our students that assimilating these two is a Bad Mistake, I wanted to know more about how this subsumption plays out, and whether it leads to trouble; or does it e.g. intimate an inference-ticket theory of the conditional? But my questions went unanswered.

Or take the chapter on propositions. We are told that for medieval logicians a proposition is a “type of sentence. i.e. a linguistic expression … singled out by its truth-evaluable character”. But then, to ask the level 101 questions, how did these medievals respond to the arguments (which would be familiar? or wouldn’t they be?) for thinking of the primary bearers of truth and falsity as being not types of sentences but rather the contents of the judgements the sentences can be used to express? Did these logicians, or some of them, end up with propositions-qua-sentences and propositions-qua-Gedanke? If not, why not? If they did, what’s the story to be told? Now, I think I take away from the chapter that there were different accounts on the market — but I really am left very unclear about what they were, how the arguments went.

One more example. There is a chapter on Sophisms and Insolubles. This ranges widely. But the result is that we get just four pages on Liar-like paradoxes. Medieval discussions of those would be well worth a chapter themselves. So as I put it before, I would have very much like to have heard more about less.

Which of course is probably just to complain, quite unfairly, that the book is not the one I really wanted, to distract and inspire as I tangle again e.g. with the issues about propositions and consequence that are bugging me as I re-rewrite the very earliest chapters of my logic text!

Posted in Logic | 2 Comments

## Category theory notes

A reminder and a request.

The reminder is for anyone interested in category theory at an introductory level — whether giving a course, or taking a course. There is a page here of links to online notes and freely available articles and books and even videos. Some have found my own work-in-progress  Category Theory: A Gentle Introduction helpful as it is particularly aimed at beginners (note however that this is pretty rough and ready in parts, and very far from finished even as a first draft — but I’m currently distracted by another project!).

## Postcard from Sicily

We have been back to Sicily for a week, this time to the north-west corner, in and around Palermo and Marsala — visiting the temple at Segesta (above) on the last day, on the way back to the airport. All in all, a delightful trip, and we did a great deal. High points included the obvious ones, visiting some Palermo sights such as the Palantine chapel, going up to Monreale, Erice, etc. Some terrific food and drink. Not least, we caught the first night of a really good production of Madame Butterfly at the Teatro Massimo in Palermo (brilliantly sung, and not too much faffing about from the director).

Ah, I see that there are a number of emails giving lots of corrections to the early draft chapters of IFL2 which I’ll need to deal with next. But first a few days off; we need a holiday to recover from the holiday …

## Intro to Formal Logic 2nd ed. — readers wanted!

It’s not so very often in life that you get a shot at putting right something major, that first time around occupied a lot of time and energy, but didn’t turn out as well as you intended. So I’m grabbing at the chance of preparing a second edition of my Introduction to Formal Logic, trying to make a very significantly better fist of it this time around. A contract hasn’t been nailed down yet, but I live in hope …

So where have things got to with the re-write? Well, you can now see the current table of contents of the reworked chapters 1 to 14. However, I am not going to simply post these chapters in an unrestricted way here (there are issues of intellectual property rights with CUP).

Still, if you would like to see these chapters, then by all means drop an email to ps218 at cam dot ac dot uk. Put “IFL” in the subject line, and add a few words about yourself (undergraduate student? graduate? professor? just interested in logic?). Then I will happily send you an e-copy of these pages on the understanding that (i) you will not recirculate them, (ii) you will certainly let me know any typos you spot, and (iii) you will give me any comments, large or small, that you have. Student comments of the “that chapter was very helpful” vs “I found that section hard going” are particularly welcome. (Though I guess that it’s too late in the day for comments, however well-meant, of the “I really wouldn’t be starting from here!” or “I wish you’d written a different kind of book!” variety. And do remember that, for better or worse, this is a book primarily aimed at beginning philosophers; so it goes slowly.)

Anyone who produces helpful comments will get further instalments of the book over the next six months, and a mention in the Thanks at the beginning of book! Fame at last: how can you resist?! (When I asked for similar help on the second edition of my Gödel book, I got a lot of corrections and suggestions which very much improved the book — and there was little correlation between someone’s official standing and the helpfulness of their comments. So all are most welcome!)

Meanwhile, I am making the opening chapters freely available — these form the informal pre-amble before we get down to propositional logic, explaining a few logical ideas like validity, forms of argument, counterexamples, proofs, etc. Beginning students who want a logical helping hand might find them useful.

## Intro to Formal Logic 2nd ed. — help, please!

If you know my Introduction to Formal Logic reasonably well, and in particular if you have at some time taught from it, do please read on!

CUP suggested over a couple of months ago now that I write a second edition of this textbook. And I have become very taken with the idea. The proposal in headline terms is that the second edition will also cover natural deduction, while losing a little of the stuff which is unnecessarily fancy for a first course. There’s just a bit more detail here. So I’ve been diving into the project (in fact, encouraged by supportive words from my CUP editor, in advance of having a formal contract). I’m well over 100 pages in, doing a very great deal of rewriting, and I think the result is a lot better — well, I would, wouldn’t I!

Now, I have just had a letter from my CUP editor, saying

Although a number of second editions of Cambridge books go forward without a review process, my senior colleagues are taking the view that for a textbook like this one, it would be good to canvass some opinion about the current edition and the changes/additions which you’re planning for the new one. They have put this request to me and to several other editors who are currently proposing second editions of textbooks.

Could you, therefore, come up with some names of people who you know are or have been using the book in teaching and who you think would be willing to give us their opinions? A group of about five or six names, including those of several people based in the US, would be extremely helpful.

Now, although I know of one or two, I confess I’ve not been keeping count of who has been using the text and who hasn’t (not a great number I think, given the sales aren’t exactly keeping me in luxury!). So if you know and like the book well enough to feel able to put in a good word with the Press for the idea of a second edition if they approach you, I’d be very grateful if you could drop me a line to ps218 at the usual cam.ac.uk.   Thanks!

Posted in IFL, Logic | 3 Comments

## CD choice #7 (Bohemian rhapsodies against the Brexit blues)

Another in my sporadic sequence of random CD recommendations. And this is, in fact a recommendation for a sequence of eight disks, called Baroque Bohemia and Beyond (or in one case Bohemian Baroque), with the Czech Chamber Philharmonic, conducted by Vojtĕch Spurný or Petr Chromčák, on the Alto label.

As the titles suggest, these are performances of (pretty obscure) Bohemian baroque and early classical symphonies and concertos, mostly composed by rough contemporaries of Haydn. Some of the composers are indeed so obscure as not to have Wikipedia pages even in Czech! And yes, the music is charming, diverting, sometimes surprising, and often delightful — but perhaps mostly not exactly great (it makes you aware once more just how consistently wonderful Haydn is!). Still, these disks have been — I’ve found — a lovely source of cheer over the last few weeks. Good to listen to while doing some of the typographical chores of converting my logic book into LaTeX for example. And an occasional very welcome and positive distraction from the post-Brexit blues (and the general sense that, politically, the world is going to hell in a handcart).

The eight discs are all freely available on Apple Music (and so, I guess, on other streaming sites?), though they also pretty cheap to buy.