When I moved here in 1997, the US seemed ahead in all sorts of ways. Since then, the UK seems to have caught up. Grocery shops sell salad dressing and ground coffee, and they’re open on Sunday. People say “kids” and “Merry Christmas”. Men don’t wear ties much, and cyclists do wear bike helmets. There are coffee shops everywhere with excellent wifi, and you get a lid on your cup at the motorway service area.

Here’s what it feels like. It has been my curious fortune to live in Britain during precisely the quarter-century when the two countries became aligned.

Of course, there is another possibility. In September I’ll be moving back to Massachusetts, and I am nervous.

[2 May 2023]

Children are oblivious to sex, and then starting as teenagers we become obsessed with it. The Bible puts sex at the very center of knowledge.

I think on balance the children’s view is the more accurate one. Yes, of course, sex is essential to survival of the species, but so are gravity and oxygen and your liver and hypothalamus, and we don’t think about those things very often. Seen from a dispassionate distance, sex is just one of hundreds of things that make our world go around.

So why do we adults, and the Bible, give it such special status? I think it’s because the way that sex works requires us to be obsessed with it. Breathing can be done unconsciously, but mating requires attention. Sex is not more important than oxygen, but knowledge of sex is more important than knowledge of oxygen.

[25 March 2023]

Hiking St. Cuthbert’s Way recently, we were reminded of how sheep run together when you come near them. Each one is determined not to be an outlier that the wolf might pick off. Safety in numbers.

It’s interesting to note that the simplest model of this behavior shows no advantage to the flock. The hungry wolf is going to take exactly one sheep, regardless of whether they’re huddled together or sparsely scattered. Thus flocking together does not improve the mean risk of death for the sheep, averaged over the flock, though it’s a big win for some of the individuals.

So the safety in numbers effect is another example like that paradoxical phenomenon that a population generally doesn’t have many more females than males, even though there could be more offspring if the ratio were ten to one. Evolution optimizes the individual, not the group.

[20 April 2023]

The word “interests” in English has two meanings:

(a) things that are to your advantage,

(b) things you find interesting.

Most people run their lives according to (a) to a degree I find had to fathom. Calculations of self-interest may be conscious (a Senator supporting Trump’s election lies) or not-so-conscious (a cyclist going without a light since the police don’t enforce that rule). (The calculation may be essentially valid or not, but that’s not my concern here.)

Which brings me to (b). So many people’s interests are so narrow! I think that’s often because they are mainly interested in things they perceive as related to their self-interest. Most people, to a degree I find hard to fathom, are not very interested in topics or activities beyond what will advance their lives and their careers. So (a) and (b) end up entwined after all.

[16 October 2022]

According to my best count, there are 16 different places that I have lived for a year or more. This becomes 22 if you look at six months or more, and 35 for three months or more.

13 years: 23 Barberry Rd, Lexington, MA, USA (1955-70)
9 years: 11 Church Way, Iffley, Oxford, UK (2013-)
7 years: 36 Jack Straws Lane, Headington, Oxford, UK (1998-2006)
6 years: 11 Hemlock Way, Ithaca, NY, USA (1991-1997)
4 years: Harvard College, Cambridge, MA, USA (1973-77)
3 years: 16 Upland Rd, Cambridge, MA, USA (1984-87)
3 years: 9 Fuller Rd, Lexington, MA, USA (1987-90)
3 years: 61 Sunningwell Rd, Oxford, UK (2009-12)
2 years: Phillips Exeter Academy, Exeter, NH, USA (1970-73)
2 years: 242 Curtner Ave, Palo Alto, CA, USA (1978-80)
2 years: Euclid Ave, East Palo Alto, CA, USA (1980-82)
2 years: Washington Square Village, New York, NY, USA (1982-84)
2 years: John Towle Close, Oxford, UK (2007-09)
1 year : 141 Moreton Rd, Summertown, Oxford, UK (1997-98)
1 year : 10 Rodean St, Fig Tree Pocket, Brisbane, Australia (2003-4)
1 year : 49 rue St. Jean, Lyon, France (2017-18)

[22 January 2023]

When I look at a mathematics paper, often I am annoyed at how badly is written. Once I decode the underlying idea being so poorly expressed, often I am annoyed at its shallowness. How can this person be so dim?

There’s an obvious paradox here. My success as a mathematics professor results precisely from my thinking more deeply and writing more clearly than most of the competition. If they were all like me, I would be just average. So why am I annoyed by the very thing that has made me successful?

I tried to figure out a resolution of this paradox and eventually realized that not every paradox has a resolution. My love of strong ideas clearly expressed is genuine. So is my love of personal success. Sometimes, one’s loves may point in contrary directions.

[8 January 2023]

Decade after decade, though the political landscape changes, Republicans and Democrats remain more or less equally balanced in the fight for political power. The Economist’s Lexington column this week tries to explain this effect, asking “Why is the country divided so evenly?”

The analogy with sex ratios in biology suggests to me that the explanation may be dynamical as well as political. The familiar paradox is that to maximize offspring, humanity would do better to have 10 women for every man, but that’s not how it happens. In such a world, men would end up with many more descendants than women. This would give a huge selection advantage to parents who gave birth to more than the usual small fraction of boy babies, quickly pushing the ratio back towards 1:1.

With political parties it won’t be as clean or as reliable, but I imagine there may be an analogous dynamic in play.

[7 January 2023]

Several of my notes assert that it is “natural” to value a nearby person more than a distant one, and a human being more than an animal or an alien. Thus I measure utility with a weight function w(x,t,s) (s=species) that decays as x/t/s move away from here/now/human. Hence my resolution of Pascal’s wager and my rejection of a key assumption of Effective Altruism.

A philosopher may object: what kind of an argument is this? What in the world does “natural” mean?

My answer is that objective moral truths do not exist. If they did, then indeed, it would be hard to see how my own place, time and species could be special. But in fact, we cannot justify moral feelings, we can only explain them, and natural selection is a big part of the explanation. That’s what “natural” means.

[20 November 2022]

At the current COP27 climate summit in Egypt, many people are pointing out how unfair it is that poorer nations are suffering the most while having done very little to bring on the problem. Climate change is the fault of the industrialized West, which is therefore morally obligated to pay “loss and damage” recompense.

I feel the power of this argument. One might quietly wonder, however, about the mathematics. If you consider the total impact of the industrialized West on the poorer nations of the world — a terrifying prospect — you see enormous negatives but enormous positives too, including the doubling of life expectancies. On balance, positive or negative? This question is so fraught, so tied to passions entirely understandable, that it’s hardly surprising it is never brought up for discussion.

[9 November 2022]

As Kate comes near the end of writing Silence: A Literary History, I find myself looking at 53 years of index card notes and mulling over a silence question of my own. There are a number of notes that I think are good, but might be better without their final sentences or paragraphs. These are cases where I present a situation and then spell out the moral explicitly. My older self now wonders, might it have been better if I had left that un-spelled out?

But it’s never a simple call. I dislike aphorisms that are slickly minimalist: it is my aim to be a philosopher, not a poet. Omitting all hints as to the point I am attempting to convey would be going too far.

Of course the poets must think about this issue all the time, and Robert Frost with his rural wisdoms was an interesting case. “Two roads diverged in a yellow wood…,” I like to imagine he mused, is a great start. Now then, should I really spell out “I took the road less traveled by, and that has made all the difference,” or is that too heavy-handed?

[14 October 2022]