Artificial neural networks are computational models inspired by the organization of neurons in the brain. They are used to model and analyze data, to implement algorithms and in attempts to understand the computational principles used by the brain. The popularity of neural networks in computer science, machine learning and cognitive science has varied wildly, both across time and between people. To an enthusiast, neural networks are seen as a revolutionary way of conceiving of computation; the entry point to robust, distributed, easily parallelizable processing; the means to build artificial intelligence systems that replicate the complexity of the brain; and a way to understand the computations that the brain carries out. To skeptics they are poorly understood and over-hyped, offering little insight into general computational principles either in computer science or in cognition. Neural networks are often called “the second best solution to any problem”. Depending on where you stand, this either means that they are often promising but never actually useful or that they are applicable to a range of problems and do almost as well as solutions explicitly tailored to the particular details of a problem (and only applicable to that particular problem).

Neural networks typically consist of a number of simple information processing units (the “neurons”). Each neuron combines a number of inputs (some or all of which come from other neurons) to give an output, which is then typically used as input to other neurons in the network. The connections between neurons normally have weights, which determine the strength of the effect of the neurons on each other. So, for example, a simple neuron could sum up all its inputs weighted by the connection strengths and give an output of 0 or 1 depending on whether this sum is below or above some threshold. This output then functions as an input to other neurons, with appropriate weights for each connection.

A computation involves transforming some stream of input into some stream of output. For example, the input stream might be a list of numbers that come into the network one by one, and the desired output stream might be the squares of those numbers. Some or all of the neurons receive the input through connections just like those between neurons. The output stream is taken to be the output of some particular set of neurons in the network. The network can be programmed to do a particular transformation (“trained”) by adjusting the strengths of connections between different neurons and between the inputs and the neurons. Typically this is done before the network is used to process the desired input, but sometimes the connection weights are changed according to some pre-determined rule as the network processes input.

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By Liam Heneghan

[This is the first in an occasional series of pieces on the philosophy of science.]

In the guestbook of a flower shop near my Evanston, Illinois home, a few blocks west of Lake Michigan – that body of water which serves as a sea for those born far from the brinier fluids of a true ocean – I observed the tiny carcass of an insect compressed upon the page, beneath a comment that read, “Yellow roses are the gift of cowards, Carl.” Intriguing. Its antennae were shaped like little Christmas trees, an anatomical curiosity permitting many people, I expect, to readily identify the fly as a chironomid midge, a fly hatched from a larva that lived in the lake’s proximate substrate, whose pupating body rose at some late life-stage and floated upon the surface of the waters, whose pupal exuvium sloughed off like the skin of a small but darkly-meated banana, and which then, as an adult, rose again to swarm as part of a male-only congregation waiting for a mate to flit along. Chironomid males, recall, have those telltale plumose antennae which act as a delicate sexual nose of sorts, to detect the presence of female flies. The ephemeral and outlandishly sexual nature of their adult lives is underscored by the fact that they do not feed, being equipped with a greatly reduced feeding apparatus. This much is well enough known; a well-informed school-child will elaborate on the matter. What drew me to this tiny creature flattened beneath the testy comment in the guest book, however, was neither its antennae nor its little head bereft of proper chompers; I was drawn to the curious genital structures of the tiny beast. I could see from the arrangement of it gonocoxites, apodemae, and sundry genital appendages that it was a Tanytarsus species. Now this, I grant you, is relatively arcane knowledge, the sort of knowledge that comes with expensive training, a scientific training. A word or two, therefore, on said training.

I qualified as a zoologist at University College Dublin, getting a master’s degree for work on chironmids that I collected in Irish National Parks in 1987, having completed my bachelor’s work the year before. I eventually earned my PhD there in 1994. A rigorous education. In our Irish system a young person shows up at university at seventeen or eighteen years of age, knowing, it is assumed, exactly what subject matters they expect to devote a lifetime of work to. Choosing, in my case, the natural sciences, I was educated in these sciences: all other domains of knowledge were excluded. I was taught (eclectically) across four science sub-disciplines in my first year, in my second specializing in three, in my third year, two, and yes in my last year I honed my skills as a zoologist taking a suite of specialist courses and undertaking a year-long research project on the systematics of a genus of chironomid midges, the Thienemannimyia group. The task: to unravel the phylogenetic (roughly evolutionary) relationships between the numerous species in the group.

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At the V&A until 20th February 2011
www.vam.ac.uk/shadowcatchers
Sponsored by Barclays Wealth

by Sue Hubbard

In his Allegory of the Cave, Plato’s chained prisoners, trapped in their subterranean world, mistook shadows cast on the wall for reality. When they spoke of the objects seen what was it they were speaking of; the object itself or its shadow? Such conundrums lie not only at the heart of western philosophical debate about the nature of reality but, also, of photography. The essence of photography involves an apparent magical ability to fix shadows on light sensitive surfaces. As far back as the second half of the eighth century, the Arab alchemist Jabir ibn Hayyan (c.721-c.815) recorded that silver nitrate – the significant element of the light-sensitive emulsion of photographs – darkened in the light. In the eighteenth century Thomas Wedgwood experimented with painting on glass placed in contact with paper and leather made chemically sensitive to the effects of light. Sadly the results remain unknown as Wedgwood lacked the know-how to fix his images.

From 1834 William Henry Fox Talbot (1800-1877) created ‘sciagrphaphs’ (the depiction of shadows) and ‘photogenic drawings’ using botanical specimens and lace placed on sensitized paper. These spectral images implicitly posed questions about the nature of reality. The term for all such works is a ‘photogram’, though strictly speaking they do not depict shadows as they are caused by the blocking of light rather than by a cast shadow. The photogram was later usurped by the process of projecting negatives through an enlarger lens. In an increasingly mechanist age this new technology proved more seductive to the scientifically minded Victorians than camera-less photography, which became the idiosyncratic realm of those interested in exploring the subconscious and the so-called spirit world. The playwright August Strindberg took to leaving sheets of photographic paper in developer exposed to the night sky, believing that his resulting ‘celestographs’ were caused by this exposure to the heavens rather than to the more prosaic explanation of dust collecting on the surface of the paper. In 1895 the previously unwitnessed interior of the human body was revealed by Wilhelm Konrad von Röntgen’s newly discovered x-rays, mirroring a growing interest in the unconscious and the revelation of that which could not be seen by the naked eye.

During the 1920s the photogram was rediscovered by a number of modern artists, particularly the Dadaists. Man Ray and László Moholy-Nagy were both attracted by its automatic qualities and the possible patterns of light that could be developed on sensitised paper without the use of any apparatus. László Moholy-Nagy wrote: “The photogram opens up perspectives of a hitherto wholly unknown morphosis governed by optical laws peculiar to itself. It is the most completely dematerialized medium which the new vision commands”. In 1937 his move to Chicago, to teach at the New Bauhaus, ensured that an interest in camera-less photography was transported across the Atlantic.

During the Second World War the role of documentary photography, with its ability to act as a witness to unpalatable truths and humanitarian concerns, became ever more important. In 1947 Robert Capa, Henri Cartier-Bresson, George Rodger and David “Chim” Seymour – photographers who had all been very much affected by what they had witnessed during the conflict – began the photographic agency Magnum, leaving the more experimental practice of camera-less techniques to the fringes of fine art practice. Now the V&A have mounted an intriguing exhibition entitled Shadow Catchers , the first UK museum exhibition of the work by contemporary camera-less photographers that includes Pierre Cordier (Belgium), Floris Neusüss (Germany), Susan Derges and Garry Fabian Miller (UK) and Adam Fuss (UK/USA).

[Photo credit: Floris Neusüss, Untitled, (Körperfotogramm), Berlin, 1962, Collection Chistian Diener, Berlin, ©Courtesy of Floris Neusüss.]

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by Fred Zackel

Didja hear?

This February, NewSouth Books will publish “Tom Sawyer” and “The Adventures of Huckleberry Finn” in a single volume, removing the “n” word and the word “injun” from the text. The word “slave” will replace the “n” word.

Mark Twain must be twirling in his grave.

Last year 2010 marked the 175th anniversary of his birth, the 100th anniversary of his death and the 125th anniversary of the American publication of “Adventures of Huckleberry Finn.”

This book “Adventures of Huckleberry Finn” is, as Lionel Trilling said, was “America's most eloquent argument against racism.”

If you never read it, don't wait for some instructor to force you.

As Twain himself said, “I never let schooling interfere with my education.”

But let’s look at what else we can “hear” from Twain, the First Great, Internationally Famous California Writer.

Oh yeah. Mark Twain was a California writer.

Listen to the Voice in this 1865 yarn, “The Celebrated Jumping Frog of Calaveras County,” his earliest success.

“I'll risk forty dollars that he can outjump any frog in Calaveras county.”

And later …

“I don't see no p'ints about that frog that's any better'n any other frog.”

The Jumping Frog was the first California International Best-seller. It made Twain famous. The story was spawned in the Gold Country. It traveled the world.

The story is about a con man getting conned. And what could be more All American?

Mark Twain said about the American art …

“To string incongruities and absurdities together in a wandering and sometimes purposeless way, and seem innocently unaware that they are absurdities, is the basis of the American art, if my position is correct.”

Yes, he was the first great California writer. Hard to believe, yes.

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by Colin Marshall

“No good movie is too long,” Roger Ebert once wrote, “and no bad movie is short enough.” Oh, how my inner cinephile regrets bringing up the 201-minute length of Jeanne Dielman, 23 quai du Commerce, 1080 Bruxelles so early in the discussion, it supports that dictum so well! Later revised to “All good films are the right length,” the line now applies to the film that much more directly. I'll sound higher-flown but surely even more accurate when I claim that the form of all good movies closely fits their substance. Here we have one of the closest form-substance matches ever made.

The title may have already given this away, but those three-and-change hours don't serve a labyrinthine plot, an ensemble of dozens, or any particular historical sweep; we get a widow, her son, three days in mid-1970s Brussels, and the preparations for those days' three dinners. Already we hit the fearsome wall this film raises against critics: having watched (and perhaps loved) it, you want to insist that, against the implication of all possible summaries, it's not boring. Yet that insistence sounds, to the rightfully skeptical reader, like too much protestation. What's more, you feel all the while that the very impulse to deliberately highlight non-boringness trivializes the many fascinating (and actually relevant) qualities of a picture so richly non-boring on every level. It's like making a big deal out of the fact that it was shot with a camera; sure, it's true, but it's also part of the work's very nature.

Generally speaking, no serious viewer considers boredom a function of length. After all, many boring movies clock in around 90 minutes, and often they're filled with event after tiresome event. Neither, then, can a serious viewer consider boredom a function of happenings. Let's not even start on all the turgid “epics” the annals of cinema history offer us. I would submit that boredom is actually the result of a form-substance mismatch; it's the unpleasant sensation of those two aspects of a film grinding away at one another, rattling, vibrating, putting out that awful burning-rubber smell. Hence the dullness of so many films adapted from other media — literature especially — as well as those conceived first and foremost as screenplays. When the material can't properly engage all the creative bandwidth cinema has to offer, something's bound to burn out. Usually, it's the audience.

Having said that, I'll tell you what happens in Jeanne Dielman. Bear with me. The titular widow's precisely scheduled days have her cooking breakfast, polishing shoes, buying ingredients, preparing impressively bland dinners out of those ingredients, eating those dinners in near-silence with her son Sylvain, reading letters from relatives in Canada, and unfolding and refolding the sofa bed. Each afternoon, she makes the time to let a different man in the front door, take him into the bedroom, and not come out until the sun sets. It's not altogether clear at first what's going on with that last bit, though Jeanne does drop a few bills into a jar on the dining table after each visit.

“A-ha,” you might say to yourself as the first day ends. “The loss of her husband has forced this poor single mother into prostitution!” To be sure, nothing in the film refutes that interpretation, but almost everything in the film hints at a deeper, stranger, far less identifiable depravity. If you're looking for indicators of homes in chaos, mothers selling sex would seem promising, yet Jeanne, whose face at certain angles looks like a death mask of domestic efficiency, could hardly have regimented her household further. Each weeknight has its dinner — Wednesdays are veal — from which there can be no deviation. Jeanne and Sylvain step out of the apartment and into town at the same time every evening. That cleanliness reigns goes without saying; even right after seeing a “client,” Jeanne takes a bath that would do an obsessive-compulsive proud.

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Why Do We Have Heads At All?
—on Daniel Lieberman’s The Evolution of the Human Head

“The head presents an evolutionary paradox,”
says Lieberman, “The roof of the orbits
is the floor of the brain.” And I imagine a room
in which a miracle sponge sits soaking up
what it means to be alive while other skulls
orbit this particular one which,
a la Ptolemy, imagines it’s a sun

This head’s tenant thinks it knows
something of the world. It sits in its domed room
sometimes as if it were a church in a cloister
somewhere emanating wishes. It wonders if
somehow it'll ever change its world. It hopes that
someday all sapient heads will in
some way plumb the paradox, lay it bare, and
sum up what they find in pithy words without in
any way diminishing the comfort of brain's appendages

“I’m not ready to ditch fossil fuels, and war's good for business,” says Id.
“Why does the head look the way it does,” asks Lieberman?
“Why do we have heads at all,” asks Jim?

by Jim Culleny, 1/9/11

In the third week of November in 2004, I dialed up to the Internet on a cellphone for the first time, then actively searched for blogs to read and bookmark. Though six years have passed, I clearly recall the first post I read through on 3quarksdaily.com. It was this one, a brief report after a trip to Karachi by Abbas Raza.

For disparate reasons (which might become clearer in future columns) the post struck some chords with me. I felt immediately sympathetic to the author and his viewpoint – a feeling since reinforced by years of devoted reading of this blog – and I was also immediately touched by his recollection of a lost “culturally diverse, tolerant, and progressive” Karachi.

Now, it is true that I have never been to Karachi. But bizarre as it may seem to many of you, large numbers of Goans cherish their connections to the city. This is because from 1850 or so, it was where we made good in numbers.

Meet May Cordeiro (b.1912), sitting with poise between her much-older siblings. She will describe herself all through her life as a Karachi girl, and will assume a lifelong posture of disdain towards everyone who comes from everywhere else.

The Cordeiro family came to Karachi from Saligao, a modest village in Goa which has never been reknowned for agriculture or natural beauty or anything similar. Instead, Saligao has distinguished itself by exporting people.

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By Tolu Ogunlesi

There were only two Nigerians in TIME Magazine’s ’60 Years of Heroes’ special issue in 2006: Writer Chinua Achebe and musician Fela Anikulapo Kuti. Apart from being artists both men were politicians too – drawn, when democracy beckoned in the late 1970s, onto that treacherous terrain by the prospects of providing an alternative to that god-awful brand of leadership Nigeria throws up with the constancy of clockwork.

Last November, I encountered both men in the United Kingdom – Fela as a reincarnated being in a National Theatre Musical (the Musical first opened on Broadway, earlier in 2010), and Achebe in flesh at Cambridge University, at a lecture he delivered in honour of Audrey Richards, the founder of the University’s Centre of African Studies.
I have written about my Achebe encounter elsewhere. Here is where I will pay my tributes to Fela, arguably the greatest musician to ever come out of Nigeria.

On the National Theatre stage in London, Fela came alive. But only just – in my opinion as a Nigerian speaker of pidgin, the corrupted version of English that served as the universal solvent for Fela’s lyrics and philosophy.

The “Fela” onstage clearly didn’t speak pidgin, he merely learnt it for the performance. And so his awkward handling of it kept getting in the – er, my – way. Fela’s pidgin (in which he delivered his trademark yabis – stinging verbal attacks on the political class, business elite and religious leaders) was as crucial to his persona as his saxophone was. Using a non-native pidgin speaker to play Fela was for me the equivalent of putting a violin in the maestro's hands.

But it was an ambitious performance, the kind one hardly ever sees in Nigeria – detailed costuming and stage set-up, and the accompanying band combined to (re)create a convincing setting. The scene in which Fela’s ‘Kalakuta Republic’ base is invaded is so well done you feel like you were a fleeing bystander on that horrible February day. Hundreds of soldiers stormed the premises on February 18, 1977, brutalising Fela’s band members, dancers and hangers-on.

By the time the soldiers were done, Kalakuta lay in ruins, and Fela's much-beloved mother, Funmilayo – the first Nigerian woman to drive a car, a woman who had left a revolt that deposed and popular monarch in the 1940s and, in defiance of the colonial authorities, visited the Soviet Union and China in the 1950s – lay dying. The soldiers had thrown her out of an upstairs window. She would die soon after.

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By Namit Arora

(An excerpt from a longer work of fiction.)

It has been a month since they first slept together. He wondered why their verbal sparring had increased in recent days. Just this morning at her place, Liz set off on the youth-obsessed American culture and the skinny ideals of female beauty manufactured by the consumer industry—a conspiracy, she said, to keep women down. ‘That’s true but what’s also true,’ he argued, ‘is that there will always be some power that will try to contain us, define us, or gain from us. Did earlier ages not have oppressive ideals of beauty? In this culture, power is exercised mainly through marketing. Fortunately, women here also have the power to free themselves from the narrow ideals of beauty impressed on them.’

‘Easier said than done,’ she retorted. ‘You don’t know the pressure this culture puts on women, how it ruins their self-esteem, causes them anxiety and self-loathing, not to mention eating disorders and health problems. These days many college sororities even have puking contests after dinner. You don’t know because you are not constantly evaluated by the shape of your tits and butt, are you?’

‘That may be because I don’t have tits,’ he tried to inject some humor.

‘What pains me more,’ she ignored his remark, ‘is the knowledge that so many women don’t see the big picture, and become co-conspirators with men in their own oppression.’

‘Co-conspirators? Wait a minute. Are you saying that men conspire to oppress women?’

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(Wherein we dump the obsolete Adam and Eve tale of the Advent of Consciousness for a more radical and contemporary one based on evolutionary psychology and cognitive neuroscience)

by

Fred Zackel, Ph.D.

“Something fell out of the mirror.”
“Did you hold it upside down?”
“Yes.”
“Did you shake it?”
“Yes.”
“After I told you not to?”
“I got curious.”

We must congratulate ourselves. Name another animal capable of creating its own meaning for its existence and then imposing it on the universe. We might even be the ones who most delay their own extinction.

Yet inside the mirror is the abyss inside us.

Let me tell you about Gregory of Nazianzus (330 – c.390) who later became Gregory, the Archbishop of Constantinople. He was known as “the Trinitarian Theologian” for his preliminary work with the emperor Theodosius on imagining the Trinity at the Second Ecumenical Council of Constantinople in 381 AD.

What? You think this Trinity popped out of the Church’s head full-blown like Athena out of Zeus? You think the Word became Flesh (snap!) just like that?

Gregory of Nazianzus argued just as we cannot look directly at the sun, we can know about it by seeing it reflected in water. So too we can know the Divine.

Our species may have gained self-awareness this way. We saw our reflection in the water hole. The word “epiphany” means seeing our place in the Great Scheme of Things.

∞

One day many millennia in the past, we human beings, each of us, one after another, saw our reflections at the water hole and for the first time. Oh, not all at once, of course. Each of us saw it independently. Some of us much sooner than others. And some of us needed it pointed out to us. But each of us saw ourselves and at that moment each of us became aware of our Self. Each of us, one after another, discovered self-awareness. Each of us had an epiphany and we learned we had individual identities, and thus, one after another, we saw our place in the Great Cosmic Scheme of Things.

What we saw was either a mirage or a miracle.

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I grew up with a mysterious man. He talks about depleting natural resources, the concept of class, Sweden’s welfare state, religion, Kyoto, corporate influence in politics, monarchy in Saudi Arabia and AIDS. And he kills people. Many, many people. I don’t understand him. I’ve never met him. I don’t even know if he’s alive anymore. I heard about him precisely on the morning of September 11, 2001. I was eleven, just starting to see the world.

I went to Peshawar in the aftermath of 9/11, an eleven-year old child, roaming the commercial streets and realizing, astounded, that the only posters as popular as the semi-naked Bollywood actresses were the close-ups of a bearded man with a raised finger, proclaimed as the “soldier of Islam”- Osama bin Laden.

I listened to my mother’s friend, sitting in our common room, speaking in hushed tones, around the end of 2001, guiltily admiring Osama, infatuated and defending, asking, after all, what had he done so wrong?

To my brain, it didn’t make sense when someone declared that if Osama bin Laden came knocking on his door in the middle of the night he would rather give him the security of his house than give him up to American troops.

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Justin E. H. Smith

The Internet, it seems, is destroying everything. In the aftermath of its Shiva-like arrival, the rest of the world now appears shabby, neglected, left over.

It has destroyed or is in the process of destroying long-familiar objects: TVs, stereos, telephones, newspapers, musical instruments, clocks, books. It is also destroying institutions: stores, universities, banks, happy hours, travel agencies. Teleconferencing is increasingly obviating the need for travel; Wikipedia is now vastly superior to anything Diderot could have imagined (and unlike the Encyclopédie, Jimmy Wales's creation is perpetually improvable). As a friend recently put it to me: to denounce Wikipedia is like denouncing the Enlightenment. Nay more: Wikipedia is the Enlightenment realized, for better or worse.

The Internet has concentrated once widely dispersed aspects of a human life into one and the same little machine: work, friendship, commerce, creativity, eros. As someone sharply put it a few years ago in an article in Slate or something like that: our work machines and our porn machines are now the same machines. This is, in short, an exceptional moment in history, next to which 19th-century anxieties about the railroad or the automated loom seem frivolous. Looms and cotton gins and similar apparatuses each only did one thing; the Internet does everything.

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Capela dos Ossos
—on a Chruch of Bones, Evora, Portugal

We pray in a church of bones
in which skulls outline graceful arches
of low vaults and whose columns are ladders
of stacked femurs. We admire its capitals
of craniums

It’s walls, unlike the idealizations
of Michelangelo, are not fantasies
romanced in fresco but the real thing:
stony remnants of once-respiring
antiquity

We pray in a church of bones
whose windows look out
beneath an osseous calcium dome

Our chapel of once-articulating skeletons
—a reliquary of calcium phosphate—
rises over a promontory like a lighthouse
warning the world of muscle and breath,
spit and sweat, bile and blood
to steer clear of the promises of ghosts
and constantly sound to avoid being
beached in mud

We pray in a church of bone
We hope in a field of dreams
We hate or love between
unknown and unknown

by Jim Culleny
Jan 1, 2010

The Church of Bones

By Jenny White

December 31, 2010 — Today on the cusp of renewal, I read a singularly deflating article in The New York Times by Susan Jacoby who, on this sunny final day of the new year, took the opportunity to remind unsuspecting readers that we are going to get old and probably do so badly, and then die. Well, I, for one, had been planning to refashion myself in the new year — more yoga, fewer pounds, a new boyfriend, a mortgage-busting advance on my next novel. Won't work; Jacoby has that covered. It seems healthy living will not protect us from Alzheimer's, one of many left hooks the indifferent cosmos jabs in our direction. And forget that “late-in-life love affair” or “financial bonanza”. What awaits us is “unremitting struggle”, Jacoby warns, and we'd better get busy identifying a health care proxy.

But why tell us now? Why not in February, when we're sunk in darkness and cold, our backs thrown out by shoveling, primed to believe the bad news? Or November, when crumpled husks of leaves cling like forlorn bats to the naked branches. I'd be willing to contemplate mortality then. Not now when the gates are flung wide open. Of course it's important to plan for the worst. But it's just as important, I would argue, to hope and not to expect the worst. Hope lights the fire under our butts that keeps us moving, even as our energy fades to black. Yeats said it better (naturally):

Everything that man esteems
Endures a moment or a day.
Love's pleasure drives his love away,
The painter's brush consumes his dreams;
The herald's cry, the soldier's tread
Exhaust his glory and his might:
Whatever flames upon the night
Man's own resinous heart has fed.

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Last month, late at night, searching for a painkiller for my wife I came upon an old stock of tablets I had been prescribed for a muscle injury. It was a combination peculiar to India, and among other drugs it included Paracetamol and Diclofenac. Since she was still breastfeeding I took care to check the tablet only to find the combination I had taken for over a week was banned in several countries due to the possibility of a life-threatening reaction.

I had been prescribed the medicine at one of many new private medical hospitals that have recently sprung up in India. The old government hospitals gave off an intense smell of phenyl (a once ubiquitous disinfectant), patients would usually spill out of the wards on to long dingy hospital corridors, wastebaskets would be overflowing with discarded injections and bloodied dressings and even a dog or two roaming the wards wouldn’t be taken amiss. They were among the few places where the existence of the Indian elite couldn’t be completely cut-off from the reality of this country.

This is no longer the case. The private hospitals are run according to the same insurance driven model that funds medical practice in the US. They cater exclusively to the post-liberalization elite and medical tourists from other countries. In look and feel they resemble the four and five star hotels that have mushroomed in the country at much the same time and pace. Over the past three years I have had reason to observe them up close as my father has gone from a healthy middle age to radiotherapy for a malignant prostate, a gallbladder removal, three major surgeries for a persistent subdural hematoma, a mild stroke, all the while requiring monitoring for his diabetes and his weakened heart. All things considered he has come out of this rather well, but now on my mobile phone instead of a single number for a general practitioner I carry the contact details of a host of specialists who individually deal with the brain, heart, prostate and other assorted body parts.

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Our visual system to seamlessly informs us about and guide us through the outside world so that we typically hardly notice its actions. However, our brain has limited processing capacity, and must filter visual input to extract the more biologically meaningful features from the totality of the visual scene. Optical illusions, in which a perception about an external scene does not match the physical reality, emerge from this filtering process. Illusions thus reveal a dissociation between the physical world and our perception of it, allowing a glimpse into the workings of the mind.

The Ebbinghaus illusion is a widely studied optical effect in which the perceived size of a circle is affected by circles of a different size surrounding it. In this illustration, most people perceive the orange circle in the right hand group as larger than the orange circle on the left. This perception is variable among individuals, with the strength of the Ebbinghaus illusion reflecting both developmental and environmental influences. The effect is absent in young subjects and in some individuals with autism, and it also varies in strength among subjects from different cultures. It can also be abolished entirely if the central circle is an object of known scale, such as a coin.

A report from last month’s Nature Neuroscience (Schwarzkopf et al.) reported an intriguing correlation between the strength of the Ebbinghaus illusion and individual functional variation in the brain. Visual information enters the body through the retina, where it is partially processed and relayed toward the primary visual cortex (V1) at the rear of the brain. The surface area devoted to V1 is known to vary by up to threefold in the general population.

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Famed ice-hockey scholar and literary critic Michael Bérubé has written in several places about the notorious Science Wars, but not always to my satisfaction, especially as we both march under the banner of post-Rortyan pragmatism. We've gone a few rounds in the past, and I haven't yet been able to make my objections clear to him; but his recent article (see also here, for an invigorating comment thread) gives me a chance to try to do better in this space.

One of Michael's concerns is to defend “theory” and “science studies” in a broad sense from its attackers like Alan Sokal (of Sokal Hoax fame). He admits that things got a little out of hand in the 80s, what with the pony-tailed left-academic brigade making the humanities look bad with (in Michael's sublimely witty rendition) “their queering this and their Piss Christ that and their deconstructing the Other”. The Hoax seemed to many to burst that Theoretic bubble and restore sanity to the academic realm, or at least provide a clear criterion for same (which, alas, not everyone meets, even now). But what is its real significance when science seems now to be threatened from another front?

As Michael relates, “[i]n my academic-left circles, Sokal’s name was mud, his hoax an example of extraordinary bad faith” while “everywhere else […] Sokal was a hero, the guy who finally exposed the naked emperor.” Michael's verdict, and mine, is more mixed. In our view, Sokal got them good, no question: anyone who knows what the axiom of choice is (or the axiom of identity, or even non-linear dynamics), would catch the joke immediately. And they didn't. This sorry result corroborates Sokal's charge that, as Michael puts it, the Social Text crowd “were overstepping their disciplinary bounds and doing 'science studies' without any substantial knowledge of science.” This is a problem, because if this is right, then they can't be familiar enough with the practices of science to say anything useful about it theoretically, as they claim to do.

On the other hand, Sokal and his fans seem to think that the hoax proved a graver charge than mere ignorance and Dunning-Kruger style hubris: that is, that among the “howlers” inserted by Sokal but missed as such by Social Text were blatantly nonsensical claims, self-refuting in the familiar way, by goofy French types like Derrida and Lyotard to the effect that objectivity is a phallogocentric myth, that there's no real world, and so on. This failure supposedly established that science studies types are soft on, or even sold on, the sort of anything-goes relativism (again supposedly) found in English departments and across the Channel.

Michael wants to preserve a role for Theory's constructive claims, so he provides a corrective designed to acknowledge the former of Sokal's charges and deflect the latter. If successful, this will allow the academic left to overcome its tradition of self-laceration long enough to confront its common enemy: right-wing irrationalism and its politicized attacks on evolutionary theory and climate science. In a way, this means that he is trying to do well what Sokal did poorly, which is to show that it is not the very idea of science and rationality, but instead adolescent rebellion against same, which — especially now — serves anti-progressive aims. This is better, again, in Michael's view, because it leaves room for the real contributions socially-minded theory can provide, rather than discarding them as pernicious nonsense and ceding the entire task to the sciences.

I will focus here on one promising but elusive slogan in Michael's corrective; but in true hermeneutic fashion, I will insist that, well, it depends on what he means.

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