Replacing yourself with a very small shell script

One of the professors this semester gave me substantial liberty to design some of the homework assignments, liberty that I am now beginning to rethink.

The students have written programs implementing various alignment algorithms, which I grade automatically with a script that runs a bunch of unit tests and reports the results. Sometimes, though, the tests fail, and I must wade into the source to figure out what happened. If you ever want to ruin a nice weekend, try reading twenty different people’s perl code back to back.

I mentioned this to my fiancee’s father. His reply: “I’ve been using perl for twenty years, and I still learn something new every time I use it. That’s a problem.”

On a somewhat disappointing correspondence

I recall reading in Wittgenstein somewhere (Notes on Certainty?) of his fear of insanity: isn’t it possible, he asked, that one could be insane without knowing it? While Wittgenstein may have been right in point of fact to doubt his sanity (the state of his own mental health was often unclear), the general point seems underappreciated to me. We sometimes experience disagreements so bewildering that we may even be unable to locate the source of the disagreement. Such encounters leave us wondering whether the other parties to the epistemic conflict are really sane at all. By symmetry, shouldn’t we extend that doubt to ourselves?

(Attention conservation notice: long, boring, internet drama, arguably with no moral to the story)

The Straussian impulse in homework

This semester I’m TA’ing for the upper level bioinformatics course.  As far as teaching assignments go, it’s really ideal: it’s my intended area of specialization, I get to work for wonderful professors and I’m afforded considerable latitude in teaching and assignment-writing.  (The latter two points were also true of cell bio last semester, though the first was definitely not.)  The bioinformatics course is unusual in that attracts both biology and computer science majors, roughly at a ratio of 1:2.  As such, there is considerable diversity in the students’ academic backgrounds, and it is expected that students will sometimes have knowledge of subjects (e.g. algorithms or biochemistry) that exceeds what is required for the course.

I think this may explain an annoying tendency in the graded assignments that I have noticed for some time but haven’t been able to put my finger on.

This tendency, which is probably more common among the CS kids than the biologists, is to lend obscure, esoteric interpretations to questions and answer them accordingly.  Mostly these involve pedantic or legalistic readings of questions which seem pretty facially straightforward to me.  For example, a warm-up question might ask for the output of an algorithm expressed in pseudo-code which prints the limiting ratio of F(n+1)/F(n), where F(n) is the nth Fibonacci number.  The facially straightforward answer to this question is 1.618… or phi, which most of the biologists were able to identify.  The legalistic, “gotcha” answer is 1, because division could be interpreted as C-style integer division.

But there is absolutely no reason to think that C-sytle semantics for the division operator were intended in the first place!  The behavior of the division operator in C was motivated by concerns of machine efficiency in general, and closure over ints specifically.  It’s not an especially important or universal fact about computer science, and there’s no reason to assume it’s implied in pseudo-code.  It actually requires “reading against the grain” of the assignment, which asked the student to identify the ratio in the next question.  Worse, the CS students know that they’re taking an interdisciplinary course where C’s division semantics is not common knowledge.

Nevertheless, the bureaucratic interpretation was depressingly common among CS students.  I would write it off as an isolated incident or a “thinko”, except that such mis-interpretations reccur with depressing regularity.  My pleas to adopt commonsensical readings of homework questions do not make a difference.

Why does this approach to homework bother me so much?  It assumes that there is an obvious interpretation of the assignment fit for commoners, and an esoteric interpretation of the text intended only for readers equipped with rare learning and subtle powers of discernment.  In other words, my students are Straussians about homework.

Ruth Barcan Marcus (1921-2012)

Sad news from Leiter that Ruth Barcan Marcus has died. I was lucky to meet Marcus once very briefly, and I described this encounter at Feminist Philosophers in a comment that a moderator suggested I repost (edited slightly for clarity):

Always sad to hear, although she led a very long and influential life. I hope it’s not out of place to share a memory, even if it’s slightly goofy.

As undergraduates, a friend and I skipped classes for the better part of a week to take a road trip to APA Central in Chicago in 2006. I was thrilled to find out that Ruth Barcan Marcus was in attendance, since I was studying her work in modal logic at the time. Her presence practically commanded every session she attended, and I think it was clear that she no longer cared a whit what others thought. I remember her developing a cough during one talk, rising without a word and inching her way down the aisle until she reached the speaker’s podium, pouring herself a glass of water from the pitcher using the speaker’s glass, drinking it while the flustered speaker attempted to continue, then returning slowly to her seat. It wasn’t an unreasonable thing to do, but it’s something that very few people would even have considered, and struck me as very bold but also very funny.

She never hesitated to spar, sometimes brusquely, with philosophers perhaps a third her age. I think her hearing was perhaps beginning to give way by then, and she spoke in a kind of 90dB monotone bark. At one point she asked a speaker to explain the so-and-so theory. The speaker launched into a vigorous defense of the so-and-so theory until Marcus cut him short: “I DON’T WANT TO DEBATE IT, I JUST WANT TO KNOW WHAT THE THEORY IS!” (Who among us can truly claim the guts to say that at a conference?) Even now, six years later, when my friends and I talk philosophy and one of us feels like we are getting snowed over, we quote Marcus at the offender.

It probably took me until the second or third day to work up the courage to ask her a question, since I was a lowly undergraduate and she, one of my living philosophical heroes. I asked her something about the logical omniscience of chickens, which unleashed a scouring attack of Dennett’s view on the matter (this had been the topic of a previous session). I barely remember the rest of the conversation, since I was struggling not to pass out from sheer awe, but getting the honor to debate the logical omniscience of chickens with Ruth Barcan Marcus was my favorite memory of that conference or any other.

Her faculties were razor-honed even at the end of her career, and the persona of queen regnant of logic that she seemed to inhabit was somehow both terrifying and charming. It must sound hyperbolic, but meeting her in person was absolutely thrilling, and remains with me now as one of my fondest memories of that time.

Intelligent Mechanics

It’s odd that the fundamentalist reaction to modern science is primarily confined to evolutionary biology. No preachers ever go after the conservation of energy, which is presumably a much larger obstacle to God’s active hand in the world.

On Examples

It’s important to give examples, but difficult to give good ones. I’m thinking primarily of the use of examples in computer science, where one can often feel tension over the issue of realism. In an expositive discussion of an algorithm, for example, a “realistic” input will usually be too large, too specific or too incidentally structured to serve a didactic purpose. On the other hand, toy examples can be counter-productive in the sense that they obscure the original motivation for the algorithm: if you have ever endured a “class Square extends Rectangle” lecture, you have felt this. Good examples negotiate these two poles and almost whisper to the reader “but you see how this generalizes…”

There is almost a sense of poignancy in shallow examples given by an author who understands their subject deeply, and there is a class of reader (including myself at times) who is liable to mistake that poignancy for condescension. Perhaps it would be better taken to
consider them as a sort of technical koan. The author admits: “I cannot foresee all of the situations in which this concept will be useful to you, yet I must pick something.”

As an aside, this sentiment seems related to a sort of meta-problem in the arts that probably has something to do with the topics of genre, idiom, and at one step removed, the Bloomean anxiety of influence. The artist knows that the audience has seen that brush stroke, read that phrase, heard that chord before. Yet the artist must do something.

The importance of examples was impressed upon me recently as I was rereading Minsky’s <i>Society of Mind</i>. I had picked it up years ago at a
free bookstore, but was put off by what struck me as an almost patronizing presentation of the subject matter. Rereading now, the examples are less cutesy, the tone more earnest, and the aim more radical than I remembered. There is something humbling in reading Minsky discussing a child playing with blocks, not because he doubts you are up for anything more complex, but because he thought it the best vehicle for the concept at hand.

FORTRAN STOP

It’s time to go to sleep when compiler errors start sounding like good ideas for t shirts.

Hello, Emacs!

This post was written and published from within Emacs, using Weblogger Mode.

I’m not dead yet!

It’s certainly been a while since the last post. The first relevant change is that this is no longer the group blog of Patrick and Ashley. This is a natural consequence of there no longer being a Patrick and Ashley, except inasmuch as required by certain mereological outlooks. Ashley’s blog is [here], although she doesn’t seem to be much better at updates than I am.

My interests have also kind of gone metastatic since my last period of activity here. In 2008, I thought it more or less obvious that philosophy was the only discipline worth personally pursuing. I have since, ah, refined that position. Recently I have been spending most of my time studying mathematics and computer science, and will be beginning a Ph.D. program in biology next fall.

As such, I’ll try to constrain the topics of this space to the biological and mathematical, but excursions and digressions will probably be inevitable.  Part of the impetus for writing again is just to force myself to put 250 words on the page every day.  There seems to be a raft of evidence suggesting that the path to human excellence–in nearly any domain–is just repeated, mindful practice.  About 10,000 hours worth.  Johnson agreed:

“In an occasional performance no height of excellence can be expected from any mind, however fertile in itself, and however stored with acquisitions. . [The author] is at liberty to delay his publication till he has satisfied his friends and himself; till he has reformed his first thoughts by subsequent examination; and polished away those faults which the precipitance of ardent composition is likely to leave behind it. Virgil is related to have poured out a great number of lines in the morning, and to have passed the day in reducing them to fewer.”
Johnson: Dryden (Lives of the Poets)

This is not to say that I don’t write currently.  In fact, I write rather a lot, but in batch-mode and usually under conditions of duress.  The point here will be to write for my own sake.  One might wonder whether it isn’t a bit presumptuous to write in the aim of attaining a form of human excellence, and of course it is presumptuous to claim to have attained it, at least without overwhelming empirical support.  Rather, I hope that the admission of a desire to practice a craft that is not wholly within one’s grasp is a humbling act, especially when that craft is one upon which most of one’s ultimate pursuits depends.

The blog’s official status at this point is quasinymity– it probably wouldn’t be too difficult to link this blog with my meatspace identity, but it’s not obvious to me whether I should encourage that identification or not.  The looming concern here is that I might write something idiotic, something which might encourage someone with a controlling interest in my future as a working scientist–like say my advisor–to conclude that I have no such thing.  The fear of publicly declaring idiotic things is a healthy one to have, but let me illustrate with an example:

I have recently decided that it is high time I learnt to program in a more traditional language, and last week I went to a short course put on by the Cambridge computer science faculty called “C for absolute beginners”…

I should perhaps add that I’ve attempted to understand C and C++ in the past, and although I didn’t manage, it was a big help this time round that I had seen at least some of it before…

I don’t know where this is going to lead. It already felt pretty complicated when we learnt about file handling (things like processing the data from one file and copying it into another), and we didn’t get on to how one might plot graphs…

The author of this excerpt is Tim Gowers. Tim Gowers the Fields Medalist. You’ve just read Tim Gowers’s admission that the C programming language was beyond him.

I don’t mention this in order to wrest some ill-gotten sense of superiority from it.  Far from it: I’m deeply indebted to Gowers for his work on the Princeton Companion to Mathematics, which is a wonderful book that you can tell has benefited from his editorial eye on practically every page.  His “informal discussions” were also extremely helpful to me when I first studied real analysis and found myself wondering what its real purpose was.  I mention that post only to introduce the moral that I derived from it, which was impressed upon me strongly enough that I can recall practically the entire post, almost two years later: there is a kind of liberation in the admission of ignorance.  If Tim Gowers can admit to being bested by a C compiler, what do I possibly have to lose?

There is a famous story, possibly apocryphal, about Rutherford–already a Nobel laureate–enrolling in freshman chemistry in order to develop the background to interpret the Geiger-Marsden experiment.  So too, then, can Gowers the Fields medalist and computational complexity theorist take “C for absolute beginners.”  I don’t think myself a Rutherford or a Gowers, of course, but I do think myself capable of learning from their examples.

Tolstoy on Greek

From Troyat’s biography:

He sent for a theological student from Moscow to teach him the rudiments of the language. From the first day, the forty-two-year-old pupil threw himself into Greek grammar with a passion, pored over dictionaries, drew up vocabularies, tackled the great authors. In spite of his headaches, he learned quickly. In a few weeks he had outdistanced his teacher. He sight-translated Xenophon, reveled in Homer, discovered Plato and said the originals were like “spring-water that sets the teeth on edge, full of sunlight and impurities and dust-motes that make it seem even more pure and fresh,” while translations of the same texts were as tasteless as “boiled, distilled water.”

Sometimes he dreamed in Greek at night. He imagined himself living in Athens; as he tramped through the snow of Yasnaya Polyana, sinking in up to his calves, his head was filled with sun, marble and geometry. Watching him changing overnight into a Greek, his wife was torn between admiration and alarm. “There is clearly nothing in the world that interests him more or gives him greater pleasure than to learn a new Greek word or puzzle out some expression he has not met before,” she complained. “I have questioned several people, some of whom have taken their degree at the university. To hear them talk, Lyovochka has made unbelievable progress in Greek.” He himself felt rejuvenated by this diet of ancient wisdom. “Now I firmly believe,” he said to Fet, “that I shall write no more gossipy twaddle of the War and Peace type.”

Hat tip: languagehat.