Public speaking

While talking just now about excellent public speakers, I remembered that I had heard a superb speech last year at a University of London graduation ceremony.  In the USA, these ceremonies are often the occasion for great speeches from invited public figures.  My experience is that this is far less often the case elsewhere in the anglophone world – the speeches tend to the routine or mundane, and outsiders are not always invited to give addresses.  Perhaps this relates to the fact the American universities, alone among those in the anglophone world, still have Departments of Speech, with serious study of argumentation, rhetoric, and oratory.  Since the switch from oral to written mathematics examinations at Cambridge in the 18th century our universities mostly no longer train or exercise people in public speaking skills, despite their evident value for so many careers.  Moreover, writing speeches is often a form of policy formulation, as experienced speech-writers attest.

At a graduation ceremony last October in the Barbican I was fortunate to hear a superb speech by Thomas Clayton, President of the Student’s Union of King’s College London, speaking in his official capacity. The speech was original, clear, inspiring, and amusing, and was pitched just right for the audience and the occasion.  Clayton himself was enthusiastic and engaged, and his speech did not sound, as many at these events do, as if he was merely going through the motions. He is evidently someone to listen out for in future.

 

Zimbabwe's cohabitation

Robert Mugabe is a superb public speaker.  I have been fortunate to hear him speak in public many times, from large ceremonial public addresses on state and official occasions, to speeches at ZANU-PF political rallies (ranging from a few hundred to several scores of thousands of people at Rufaro Stadium, and with both sophisticated urban and traditional rural participants), to addresses to foreign investors and business leaders, to quiet, grave-side orations at funerals of mutual friends.  And I have expressed before my admiration for his rhetorical skills, his superb command of different registers, his intelligence, his Jesuit-trained casuistry, and his guile.  I have never met him, but from accounts of people who have, he can also be very charming when he wishes.

Despite claims by some that he has become diminished with age, and even falls asleep during official meetings, the opposition ministers in his Cohabitation Government say that he is just as charming, intelligent, and wily as ever.  From a  report this week in the Guardian:

Welshman Ncube, Zimbabwe’s Minister of Commerce and Industry and leader of one of the factions of the Movement for Democratic Change (MDC), lost his grandfather in the 1980s Gukurahundi. The Gukurahundi was a violent campaign in which thousands of opposition Zimbabwe African Peoples Union (Zapu) party supporters were killed and beaten by a brigade owing allegiance to President Robert Mugabe’s government.
Ncube shares his experience working with Mugabe in a unity government since 2009: “Ninety percent of the time, I cannot recognise the Mugabe I sit with in cabinet with the Mugabe who has ruled this country through violence. He shows real concern for his country and people, like a father. And he can master detail over a wide range of government matters. If I had only this experience with Mugabe in government and had not lived through the Gukurahundi and seen him denouncing Zapu with anger and belief on television, and you told me he carried out the Gukurahundi, I would say ‘no, not this man, he is not capable of it’. But I saw him.”
Another MDC minister, Priscilla Misihairabwi-Mushonga, also struggles to reconcile the man she thought Mugabe was, before entering government, with the one she knows today. “I did not think Mugabe believed in things. Now I know that Mugabe actually believes in things, ideologically, like that the British are after regime change in Zimbabwe. When he believes in something he will genuinely defend it. If he believes in an action, no matter how wrong it is, he will not apologise. That is one hallmark of Mugabe. He is loyal to his beliefs.”
On Mugabe’s personality, Misihairabwi-Mushonga says that she had not known that he was “a serious charmer around women. A very, very, very good charmer . . .  He also has an exceptional sense of humour. You literally are in stitches throughout cabinet. But he also has an intellectual arrogance. If you do not strike him as someone intelligent he has no time for you. There are certain people who, when they speak in cabinet, he sits up and listens, and others who, when they speak, he pretends to be asleep.”
Nelson Chamisa, the MDC Minister of Information and Communication Technology, once thought Mugabe was “unbalanced”, but adds: “sitting in cabinet with him, I admire his intellect. He has dexterity of encyclopaedic proportions. He is bad leader but a gifted politician. Why do I say he is a gifted politician? He has the ability to manage political emotions and intentions. But leadership is a different thing. The best form of leadership is to create other leaders who can come reproduce your vision after you. Mugabe has not done that.”

I add a note to clarify this post: None of the above should be seen as an endorsement of Mugabe’s policies, many of which have been motivated by malfeasance, peculation, and plain, old-fashioned, evil.  Unfortunately, his administration, unlike many in Africa, has been overwhelmingly competent, with even the policy of hyperinflation aimed – deliberately and very successfully – at enriching a few thousand people having foreign currency holdings at the expense of every other Zimbabwean.   The pinnacle of this deadly-effective malevolence has been the enrichment of the political and military elite by use of the state’s military forces to operate protection rackets in foreign countries  – eg, in the Democratic Republic of the Congo, with whom Zimbabwe shares no border nor any strategic interest.

Scotland under cyber attack?

In the past, global empires such as those of Rome or Britain or France could face attacks from anywhere across the empire.   Britain, for instance, fought Imperial wars in Southern Africa and Afghanistan.   The Internet takes us back to that situation – any country, no matter how small or obscure, potentially faces cyber espionage or incursions or attacks from people anywhere in the world.   Ask Estonia or Denmark, both small countries that came under attack from cyber attackers.
The Roman Empire never did manage to subdue the belligerent peoples in what is now Scotland.   How ironic, then, that Scots nationalists seem not to have realized that an independent nation will need to defend itself from global attack.   MP Rory Stewart has reminded them, asking some hard, clear-light-of-day, questions about the romantic, candle-lit, vision of Scottish independence.   Questioning Nicola Sturgeon, Scotland’s Deputy First Minister, who was appearing before the UK House of Commons Committee on Foreign Affairs, Stewart asked about independent Scotland’s plans for intelligence and security:

Sturgeon came under repeated pressure from the Tory MP for Penrith and the Border, Rory Stewart, a former army officer and Foreign Office diplomat, to explain how an independent Scotland would build, equip, train and fund its own spying and security services.
Stewart said the UK’s current annual spying and security budget did not include the total historic costs of building and equipping its intelligence services, from setting up secure intelligence units in overseas embassies, training its agents, to building and equipping GCHQ.
It would cost billions, he said, to set up the secure communications Scotland needed for its intelligence agencies. For instance, if an independent Scotland wanted to have the same number of embassies overseas as Ireland, which has 97, or Finland, which has 93, it would cost hundreds of millions to equip them.”

One day in the life . . .

. . . of Boris N. Delone (1890-1980), Russian mathematician, moutaineer, and polymath, member of a famous family of mathematicians and physicists, whose grandson was a dissident poet:

July 6, 1975, Delone spends a cold night (-25 degrees C) in a tent on a glacier under the beautiful peak of Khan Tengri (7000 m, the Tien Shan mountain system, Central Asia) [pictured, at sunset] at a height of about 4200 m.  In the morning a helicopter picks him up to take him to Przhevalsk (now Karakol), a Kyrgyz city at the eastern tip of Lake Issyk-Kul.  From Przhevalsk he takes a local flight to Frunze (now Bishkek), the capital of Kyrgyzstan, where the heat exceeds 40 degrees C.   After queuing up for a few hours and with the help of some “kind people” and the Academy of Sciences membership card he succeeds in purchasing an air ticket to Moscow.   Late at night he arrives at Domodedovo airport in Moscow, from which he still needs to go to his country house near Abramtsevo (Moscow oblast).   Taking the last commuter train, he arrives at the necessary station at around 2 am; from there it is another three kilometers to his house, half of which are in a dark dense forest.  He loses his way and, after roaming around the night forest for a long time, leaves his heavy rucksack in a familiar secluded place.  Only in the morning does Delone succeed in getting home safely.”  (page 13).

In that year, 1975, Boris Delone was 85 years old.

N. P. Dolbilin [2011]: Boris Nikolaevich Delone (Delaunay): Life and Work. Proceedings of the Steklov Institute of Mathematics, 275: 1-14.  Published in Russian in Trudy Matematicheskogo Instituta imeni V. A. Steklov, 2011, 275:  7-21.  A pre-print version of the paper is here.

Bayesianism in science

Bayesians are so prevalent in Artificial Intelligence (and, to be honest, so strident) that it can sometimes be lonely being a Frequentist.   So it is nice to see a critical review of Nate Silver’s new book on prediction from a frequentist perspective.   The reviewers are Gary Marcus and Ernest Davis from New York University, and here are some paras from their review in The New Yorker:

Silver’s one misstep comes in his advocacy of an approach known as Bayesian inference. According to Silver’s excited introduction,
Bayes’ theorem is nominally a mathematical formula. But it is really much more than that. It implies that we must think differently about our ideas.
Lost until Chapter 8 is the fact that the approach Silver lobbies for is hardly an innovation; instead (as he ultimately acknowledges), it is built around a two-hundred-fifty-year-old theorem that is usually taught in the first weeks of college probability courses. More than that, as valuable as the approach is, most statisticians see it is as only a partial solution to a very large problem.
A Bayesian approach is particularly useful when predicting outcome probabilities in cases where one has strong prior knowledge of a situation. Suppose, for instance (borrowing an old example that Silver revives), that a woman in her forties goes for a mammogram and receives bad news: a “positive” mammogram. However, since not every positive result is real, what is the probability that she actually has breast cancer? To calculate this, we need to know four numbers. The fraction of women in their forties who have breast cancer is 0.014, which is about one in seventy. The fraction who do not have breast cancer is therefore 1 – 0.014 = 0.986. These fractions are known as the prior probabilities. The probability that a woman who has breast cancer will get a positive result on a mammogram is 0.75. The probability that a woman who does not have breast cancer will get a false positive on a mammogram is 0.1. These are known as the conditional probabilities. Applying Bayes’s theorem, we can conclude that, among women who get a positive result, the fraction who actually have breast cancer is (0.014 x 0.75) / ((0.014 x 0.75) + (0.986 x 0.1)) = 0.1, approximately. That is, once we have seen the test result, the chance is about ninety per cent that it is a false positive. In this instance, Bayes’s theorem is the perfect tool for the job.
This technique can be extended to all kinds of other applications. In one of the best chapters in the book, Silver gives a step-by-step description of the use of probabilistic reasoning in placing bets while playing a hand of Texas Hold ’em, taking into account the probabilities on the cards that have been dealt and that will be dealt; the information about opponents’ hands that you can glean from the bets they have placed; and your general judgment of what kind of players they are (aggressive, cautious, stupid, etc.).
But the Bayesian approach is much less helpful when there is no consensus about what the prior probabilities should be. For example, in a notorious series of experiments, Stanley Milgram showed that many people would torture a victim if they were told that it was for the good of science. Before these experiments were carried out, should these results have been assigned a low prior (because no one would suppose that they themselves would do this) or a high prior (because we know that people accept authority)? In actual practice, the method of evaluation most scientists use most of the time is a variant of a technique proposed by the statistician Ronald Fisher in the early 1900s. Roughly speaking, in this approach, a hypothesis is considered validated by data only if the data pass a test that would be failed ninety-five or ninety-nine per cent of the time if the data were generated randomly. The advantage of Fisher’s approach (which is by no means perfect) is that to some degree it sidesteps the problem of estimating priors where no sufficient advance information exists. In the vast majority of scientific papers, Fisher’s statistics (and more sophisticated statistics in that tradition) are used.
Unfortunately, Silver’s discussion of alternatives to the Bayesian approach is dismissive, incomplete, and misleading. In some cases, Silver tends to attribute successful reasoning to the use of Bayesian methods without any evidence that those particular analyses were actually performed in Bayesian fashion. For instance, he writes about Bob Voulgaris, a basketball gambler,
Bob’s money is on Bayes too. He does not literally apply Bayes’ theorem every time he makes a prediction. But his practice of testing statistical data in the context of hypotheses and beliefs derived from his basketball knowledge is very Bayesian, as is his comfort with accepting probabilistic answers to his questions. 
But, judging from the description in the previous thirty pages, Voulgaris follows instinct, not fancy Bayesian math. Here, Silver seems to be using “Bayesian” not to mean the use of Bayes’s theorem but, rather, the general strategy of combining many different kinds of information.
To take another example, Silver discusses at length an important and troubling paper by John Ioannidis, “Why Most Published Research Findings Are False,” and leaves the reader with the impression that the problems that Ioannidis raises can be solved if statisticians use Bayesian approach rather than following Fisher. Silver writes:
[Fisher’s classical] methods discourage the researcher from considering the underlying context or plausibility of his hypothesis, something that the Bayesian method demands in the form of a prior probability. Thus, you will see apparently serious papers published on how toads can predict earthquakes… which apply frequentist tests to produce “statistically significant” but manifestly ridiculous findings. 
But NASA’s 2011 study of toads was actually important and useful, not some “manifestly ridiculous” finding plucked from thin air. It was a thoughtful analysis of groundwater chemistry that began with a combination of naturalistic observation (a group of toads had abandoned a lake in Italy near the epicenter of an earthquake that happened a few days later) and theory (about ionospheric disturbance and water composition).
The real reason that too many published studies are false is not because lots of people are testing ridiculous things, which rarely happens in the top scientific journals; it’s because in any given year, drug companies and medical schools perform thousands of experiments. In any study, there is some small chance of a false positive; if you do a lot of experiments, you will eventually get a lot of false positive results (even putting aside self-deception, biases toward reporting positive results, and outright fraud)—as Silver himself actually explains two pages earlier. Switching to a Bayesian method of evaluating statistics will not fix the underlying problems; cleaning up science requires changes to the way in which scientific research is done and evaluated, not just a new formula.
It is perfectly reasonable for Silver to prefer the Bayesian approach—the field has remained split for nearly a century, with each side having its own arguments, innovations, and work-arounds—but the case for preferring Bayes to Fisher is far weaker than Silver lets on, and there is no reason whatsoever to think that a Bayesian approach is a “think differently” revolution. “The Signal and the Noise” is a terrific book, with much to admire. But it will take a lot more than Bayes’s very useful theorem to solve the many challenges in the world of applied statistics.” [Links in original]

Also worth adding here that there is a very good reason experimental sciences adopted Frequentist approaches (what the reviewers call Fisher’s methods) in journal publications.  That reason is that science is intended to be a search for objective truth using objective methods.  Experiments are – or should be – replicable  by anyone.   How can subjective methods play any role in such an enterprise?  Why should the  journal Nature or any of its readers care what the prior probabilities of the experimenters were before an experiment?    If these prior probabilities make a difference to the posterior (post-experiment) probabilities, then this is the insertion of a purely subjective element into something that should be objective and replicable. And if the actual numeric values of the prior probabilities don’t matter to the posterior probabilities (as some Bayesian theorems would suggest), then why does the methodology include them?  
 

Hard choices

Adam Gopnik in the latest New Yorker magazine, writing of his former teacher, McGill University psychologist Albert Bregman:

he also gave me some of the best advice I’ve ever received.  Trying to decide whether to major in psychology or art history, I had gone to his office to see what he thought.   He squinted and lowered his head.  “Is this a hard choice for you?” he demanded.  Yes! I cried. “Oh,” he said, springing back up cheerfully.   “In that case, it doesn’t matter.  If it’s a hard decision, then there’s always lots to be said on both sides, so either choice is likely to be good in its way.  Hard choices are always unimportant. ” (page 35, italics in original)

I don’t agree that hard choices are always unimportant, since different options may have very different consequences, and with very different footprints (who is impacted, in what ways, and to what extents).  Perhaps what Bregman meant to say is that whatever option is selected in such cases will prove feasible to some extent or other, and we will usually survive the consequences that result.  Why would this be?    I think it because, as Bregman says, each decision-option in such cases has multiple pros and cons, and so no one option uniformly dominates the others.  No option is obviously or uniformly better:  there is no “slam-dunk” or “no-brainer” decision-option.  
In such cases, whatever we choose will potentially have negative consequences which we may have to live with.  Usually, however, we don’t seek to live with these consequences.  Instead, we try to eliminate them, or ameliorate them, or mitigate them, or divert them, or undermine them, or even ignore them.  Only when all else fails, do we live in full awareness with the negative consequences of our decisions.   Indeed, attempting to pre-emptively anticipate and eliminate or divert or undermine or ameliorate or mitigate negative consequences is a key part of human decision-making for complex decisions, something I’ve called (following Harald Wohlrapp), retroflexive decision-making.   We try to diminish the negative effects of an option and enhance the positive effects as part of the process of making our decision.
As a second-year undergraduate at university, I was, like Gopnik, faced with a choice of majors; for me it was either Pure Mathematics or English.    Now, with more experience of life, I would simply refuse to make this choice, and seek to do both together.  Then, as a sophomore, I was intimidated by the arguments presented to me by the university administration seeking, for reasons surely only of bureaucratic order, to force me to choose:  this combination is not permitted (to which I would respond now with:  And why not?); there are many timetable clashes (I can work around those);  no one else has ever asked to do both (Why is that relevant to my decision?); and, the skills required are too different (Well, I’ve been accepted onto Honours track in both subjects, so I must have the required skills).   
As an aside:  In making this decision, I asked the advice of poet Alec Hope, whom I knew a little.   He too as an undergraduate had studied both Mathematics and English, and had opted eventually for English.  He told me he chose English because he could understand on his own the poetry and fiction he read, but understanding Mathematics, he said, for him, required the help of others.  Although I thought I could learn and understand mathematical subjects well enough from books on my own, it was, for me, precisely the social nature of Mathematics that attracted me: One wasn’t merely creating some subjective personal interpretations or imaginings as one read, but participating in the joint creation of an objective shared mathematical space, albeit a space located in the collective heads of mathematicians.    What could be more exciting than that!?
More posts on complex decisions here, and here
Reference:
Adam Gopnik [2013]: Music to your ears: The quest for 3D recording and other mysteries of sound.  The New Yorker, 28 January 2013, pp. 32-39.

Listening to music by jointly reading the score

Another quote from Bill Thurston, this with an arresting image of mathematical communication:

We have an inexorable instinct to convey through speech content that is not easily spoken.  Because of this tendency, mathematics takes a highly symbolic, algebraic, and technical form.  Few people listening to a technical discourse are hearing a story. Most readers of mathematics (if they happen not to be totally baffled) register only technical details – which are essentially different from the original thoughts we put into mathematical discourse.  The meaning, the poetry, the music, and the beauty of mathematics are generally lost.  It’s as if an audience were to attend a concert where the musicians, unable to perform in a way the audience could appreciate, just handed out copies of the score.  In mathematics, it happens frequently that both the performers and the audience are oblivious to what went wrong, even though the failure of communication is obvious to all.” (Thurston 2011, page xi)  

Reference:
William P. Thurston [2011]:   Foreword.   The Best Writing on Mathematics: 2010.  Edited by Mircea Pitici.  Princeton, NJ, USA:  Princeton University Press.

Mathematical thinking and software

Further to my post citing Keith Devlin on the difficulties of doing mathematics online, I have heard from one prominent mathematician that he does all his mathematics now using LaTeX, not using paper or whiteboard, and thus disagrees with Devlin’s (and my) views.   Thinking about why this may be, and about my own experiences using LaTeX, it occurred to me that one’s experiences with thinking-support software, such as word-processing packages such as MS-WORD or  mark-up programming languages such as LaTeX, will very much depend on the TYPE of thinking one is doing.
If one is thinking with words and text, or text-like symbols such as algebra, the right-handed folk among us are likely to be using the left hemispheres of our brains.  If one is thinking in diagrams, as in geometry or graph theory or much of engineering including computing, the right-handed among us are more likely to be using the right hemispheres of our brains.  Yet MS-WORD and LaTeX are entirely text-based, and their use requires the heavy involvement of our left hemispheres (for the northpaws among us).  One doesn’t draw an arrow in LaTeX, for example, but instead types a command such as \rightarrow or \uparrow.   If one is already using one’s left hemisphere to do the mathematical thinking, as most algebraists would be, then the cognitive load in using the software will be a lot less then if one is using one’s right hemisphere for the mathematical thinking.  Activities which require both hemispheres are typically very challenging to most of us, since co-ordination between the two hemispheres adds further cognitive overhead.
I find LaTeX immeasurably better than any other word-processor for writing text:  it and I work at the same speed (which is not true of MS-WORD for me, for example), and I am able to do my verbal thinking in it.  In this case, writing is a form of thinking, not merely the subsequent expression of thoughts I’ve already had.     However, I cannot do my mathematical or formal thinking in LaTeX, and the software is at best a tool for subsequent expression of thoughts already done elsewhere – mentally, on paper, or on a whiteboard.    My formal thinking is usually about structure and relationship, and not as often algebraic symbol manipulation.
Bill Thurston, the geometer I recently quoted, said:

I was interested in geometric areas of mathematics, where it is often pretty hard to have a document that reflects well the way people actually think.  In more algebraic or symbolic fields, this is not necessarily so, and I have the impression that in some areas documents are much closer to carrying the life of the field.”  [Thurston 1994, p. 169]

It is interesting that many non-mathematical writers also do their thinking about structure not in the document itself or as they write, but outside it and beforehand, and often using tools such as post-it notes on boards; see the recent  article by John McPhee in The New Yorker for examples from his long writing life.
References:
John McPhee [2013]: Structure:  Beyond the picnic-table crisisThe New Yorker, 14 January 2013, pages 46-55.
William F. Thurston [1994]:  On proof and progress in mathematicsAmerican Mathematical Society, 30 (2):  161-177.

Vale: Dave Brubeck

The BBC Radio 3 program Jazz Record Requests had a special edition yesterday in memory of Dave Brubeck.  It is available to listen for another 6 days, here.   
I heard Brubeck and his quartet play a concert in Liverpool about 10 years ago. He was old enough to have to shuffle slowly onto stage, but once at the piano, his playing was alive and energetic. My only disappointment was that he performed a concert in Liverpool and not once made any reference to the music of the city’s most famous musical sons. We could have been in Outer Woop Woop, for all the difference it had on his choice of repertoire. Not even an allusion in an improvisation was just churlish.
Brubeck’s reknown was remarkable.   I once requested a busking middle-aged violinist in a Kiev cafe in the mid 1990s to play Take Five, and saw his face light up with delight.  As it happened, he also knew The Hot Canary.

Thurston on mathematical proof

The year 2012 saw the death of Bill Thurston, leading geometer and Fields Medalist.   Learning of his death led me to re-read his famous 1994 AMS paper on the social nature of mathematical proof.   In my opinion, Thurston demolished the views of those who thought mathematics is anything other than socially-constructed.  This post is just to present a couple of long quotes from the paper.
Continue reading ‘Thurston on mathematical proof’