This and that

Postcard from Cornwall

The first time back in St. Mawes since the beginning of the pandemic. A magical place. It has been wonderful to look out over the harbour even on wetter, greyer days: a delight from early morning to the very end of the day. And we have walked and walked hereabouts. Cobwebs blown away. For a couple of weeks, the dire mess of the wider world seems particularly far away.

Soon, it‘s back to Cambridge, to category theory (I’m promising a much better chapter on equalizers/co-equalizers), some musings on a philosophical view from Terence Tao, some potshots at a recent dreadful intro book on formal logic. But just for now, logic can look after itself. The sun is going down over Roseland. Calm sea. Peace.

That nothing is certaine

I’ve been trying to put together better notes on elementary category theory; which is an engaging exercise, but that doesn’t lead to anything very interesting to report here. Another thing occupying me on and off has been writing quite extensive comments on a draft book by an ex-colleague: but although that does raise very interesting issues, it mostly wouldn’t be appropriate to rehearse them here.

Then there have been time-consuming domestic chores — including tackling the Book Problem once again. This time round, it’s been the non-work books. Piles around the house acquired over lockdown (and I’m not the only guilty party) were beginning to totter. So it’s been the occasion for an overdue major sort-out, with re-shelvings, donations of bags of books to Oxfam, and all those discussions “are either of us ever going to read that/read that again?”. Yes, I would for example, have liked to have read the  massive biography of Darwin: but life is too short (a phrase that becomes ever more telling as the birthdays clock by). That’s a precious three inches of shelf-space reclaimed. And so on it goes … But hardly the topic for a riveting essay here!

But perhaps the main reason for the lack of many posts recently has been low spirits as much as anything: try as you might, the state of the world just gets you down, no? The grim uncertainty of it all. But then,

… these things every one doe enwrap and entangle silly mortall men, void of all forecast and true understanding: so as this only point among the rest remains sure and certain, namely: That nothing is certaine …

Thus Pliny, “done into English” by Philemon Holland.

Philosophical Uses of Categoricity Arguments

Peter F. has written:

I wanted to let you know about a paper that was recently put on the arXiv which I think you and many readers of this site will find very interesting, in case it hasn’t been noticed yet:

Penelope Maddy & Jouko Väänänen “Philosophical Uses of Categoricity Arguments” https://arxiv.org/abs/2204.13754

This does indeed on a quick skim look a seriously interesting and thought-provoking paper (though not an easy read: there is a lot of detailed argument here). Thanks for the pointer!

Like it or not, again

I experimented with a ‘like’ button for blog posts for ten days. I thought it probably wouldn’t be used much, and it turns out I was right (for I know that each post is actually read hundreds of times). So I’ve decluttered and removed the button again.

In fact, everything about “user engagement”, as they say, remains a bit of a mystery to me. It is very nice to know, for example, that the Beginning Math Logic study guide has already been downloaded almost a thousand times this month. But how the word gets around, who the readers are, what they make of the guide, is all pretty unfathomable.

Never mind. The overall site statistics (whatever they mean in absolute terms) continue to look perfectly healthy. So as long as I’m not entirely talking to myself, on we go …

Like it or not ….

Drat, I missed the blog’s birthday. Now sweet sixteen!

In an experimental way, I have added a “like” button, just to appear on blog posts. So please “like” what you do like enough. It will be interesting to know what finds the most favour, and that might even affect a bit what I choose to blog about. Or not, as the case might be …

A quarter’s novels

For a while, I’ve been trying to read a dozen novels a quarter, and so far this year I’m (almost) on track, having read

1. Abir Mukerjee, A Rising Man
2. Pat Barker, The Women of Troy
3. Elizabeth Strout, Oh William
4. Barbara Pym, Jane and Prudence
5. (Elif Shafak, The Architect’s Apprentice)
6. Kate Atkinson, Behind the Scenes at the Museum
7. Antonia Byatt, Possession
8. Benjamin Black, Christine Falls
9. Ivan Turgenev, Home of the Gentry
10. Andrea Levy, Small Island
11. Ruth Prawer Jhabvala, Heat and Dust
12. Mary Lawson, A Town Called Solace

I tried Abir Mukerjee’s Indian detective story as light relief having just finished Anna Karenina once more; but I found it very disappointing —  the plot rather routine, and surprisingly thinly painted local colour. But both the new Pat Barker and new Elizabeth Strout are as predictably brilliant as all the reviewers said. And Barbara Pym, a late discovery for me, is always a delight (at least for an English reader of a certain vintage).

I’m cheating a bit listing Elif Shafak’s book here, as I didn’t finish it. It is extraordinary, but to be honest before the end I got bored …. So I picked up one of the always hugely enjoyable Kate Atkinsons to re-read. Next, the weighty Possession has been on our shelves a lifetime, and I realised about a third of the way through that I had never read it all before: it now strikes me as very impressive on many levels, and I’m sure I missed much.

After that, for lighter entertainment again, I tried the first of the books by John Banville writing as Benjamin Black. Beautifully written as you might predict, and I rattled through it: but I’m not sure I’ll be returning to the series.

Turgenev remains a favourite, and I seem to have re-read most of his main novels in the last two or three years. Our old Penguin copy of Home of the Gentry had fallen to bits, and I bought a more recent translation which seemed occasionally oddly wrong in tone — so I found myself returning to the later half of the Penguin which was still intact. And then Small Island is wonderfully humane and engaging, and definitely worth revisiting. But while Heat and Dust won the Booker Prize, once upon a time, that fact today seems very surprising; this does now seem to be a rather insubstantial novel.

Finally, Mary Lawson’s A Town Called Solace comes recommended by Anne Tyler, and you can see why. I suppose this too is also slight in its way; but it is one of those books with overlapping small domestic worlds, touched by human dramas, which ambushes you as you realise that you have become so attached to the three central characters that you don’t want the book to end as soon as it does.

If I had to recommend just one of the newer books as a must-read? Elizabeth Strout’s perhaps. Wonderful writing and real feeling for the complexities of ordinary human relationships.

Online mini-conference on logical pluralism

Just a reminder that I’m very happy occasionally to announce here new books, online conferences, etc., that are likely to be of interest to enough readers of this blog. Just let me know if you have something suitable you want to publicise.

So: there is an online three-paper conference Logical Pluralism:  One logic, or many logics? announced for Friday April 1st (from 10 am, EST), from James Madison University:

  • “Perspectival Logical Pluralism”   Roy T. Cook (Minnesota)
  • “Logical Pluralism: Boring Truth? Exciting  Falsehood?”  Erik Stei (Utrecht)
  • “Logical Pluralism and Logical Disputes”  Teresa Kouri Kissel (Old Dominion Univ.)

Zoom links etc. available from the conference webpage here.

War plates



From a series of six at the Ai Weiwei exhibition in Cambridge. Extraordinarily evocative, appallingly timely.

Update of BML

Oh dear. That’s very embarrassing. I spotted a horrid thinko at the top of p. 77 of printed version of Beginning Mathematical Logic. I can hardly believe that I wrote, concerning infinite binary strings and real numbers between 0 and 1, that “different strings represent different reals”. Ouch. So replace the para numbered “2.” by

Note too that a real number between 0 and 1 can be represented in binary by an infinite string. And, by the same argument as before, for any countable list of reals-in-binary between 0 and 1, there will be another such real not on the list. Hence the set of real numbers between 0 and 1 is again not countably infinite. Hence neither is the set of all the reals. 

I’ve updated the online PDF, and uploaded a corrected file to Amazon which will take a couple of days to work through the system). And I’ll start a corrections page for those who have the first printings of the book.

I’m not going to fret about every minor typo. But I will correct major mistakes that could mislead the reader (and then, when I do, I’ll take the opportunity to correct any smaller errors I know about). I won’t add new content though: that can wait until a second edition …!

Update Amazon reports that changes are now live: so a book ordered from now on should be the very-slightly-revised version (dated 18 Feb on the verso of the title page).

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