Thursday, May 31, 2018

From Single Neurons to Ultrasociality

From Single Neurons to Ultrasociality

What can one neuron tell us about brain function?  Neuroscientists "jumped out of their chairs" when they stumbled across one neuron in one brain that meant the patient was looking at a picture of Jennifer Aniston - any of several very different pictures of Jennifer Aniston, and showed no response to any other stimuli.

In 2005, a brain surgeon and researcher named Itzak Fried was probing part of the brain  in patients with epilepsy to pinpoint the source of their seizures.  This is open brain surgery done while the patient is conscious (the brain doesn’t have pain receptors).  These patients agreed to additional probing in the interest of science.  Fried was showing patients pictures  of famous people, and kept running into neurons that would fire to multiple representations of the same person.  “The first time we saw a neuron firing to seven different pictures of Jennifer Aniston–and nothing else–we literally jumped out of our chairs,” recalled R. Quian Quiroga, who did subsequent work on the phenomenon with Fried.

Serious study of neurons in the brain have gone on for more than a century, yet any new discovery that can say "This neuron does X" is apt to strongly excite the neuroscience community, and leak out into the world of journalism.

In a study by Quiroga, Fried and others, severe epilepsy patients each had 64 tiny probes implanted in different parts of the brain, to study the origin and paths of spreading of the spasms of excitement that make up a seizure. The patients also agreed to view sets of images while the probes were monitored, in the general interest of science. A number of invariant responses (the same neuron firing to multiple views of the same person/thing) were found.  “In some patients, Jennifer Aniston neurons would also fire to her fellow actresses in Friends, … But they would never fire to other similar-looking, but otherwise unconnected, actresses” (Nature Magazine).  Either way, a connection was made between a concept and a single neuron.  Already, for seven decades, we have had demonstrations that single neuron stimulation can trigger laughter, remembered childhood scenes or hearing snippets of music, but listening to neurons.  But finding an association with a concept, such as that of a certain person, was quite new, and instantly became and remains a major focus of brain research.

Mirror Neurons

About 10 year earlier, Italian neuroscientists were studying macaque monkeys with their brains exposed to probing, trying to map body movements to particular motor neurons.  They found a neuron that fired whenever the monkey grasped something, just the sort of thing they were looking for.  But then the same neuron was seen to fire when one of the lab workers grasp something, and this turned out to be very replicable.

So the monkey watches someone grasp something, and has an inner experience of grasping it himself?  And could imagining a hand movement possibly cause motor neurons to fire as if one were actually performing it without causing the imagined movement?  If dreaming is a kind of imagination, the answer is yes.  Studies have shown that during dreams, our brains initiate a lot of starting sequences for action, that are somehow inhibited, unless, that is, one has a disorder connected with excessive thrashing in bed and even sleepwalking.

The other startling thing is for monkeys to be so in touch, with another being who happens to have hands, as to spontaneously imagine doing what the other is doing, and in such a neurologically realistic way.  We might call this phenomenon motoric empathy.  The  finding was replicated in many variations, and analogues were found in human beings.

Neurons that fire both when you are doing something, and when the same action is observed, were dubbed “mirror neurons”. It sounded, and still sounds, in some accounts, like mirror neurons were a particular unique kind of neuron whose function is to cause or indicate empathy, but as with the “Jennifer Aniston neurons”, the "mirror neuron" could just be some neuron in or connected to a brain circuit for producing grasping movements was encountered. The "mirroring" is whatever happens between seing a hand grasping, and some kind of inhibited (in this case) impulse to grasp in the same way.

Mirror neurons are also used to support the “Simulation Theory” of mindreading in Alvin Goldman’s Simulating Minds: The Philosophy, Psychology, and Neuroscience of Mindreading (2008) .  By “mindreading”, or “theory of mind”, philosophers and cognitive scientists mean our ordinary ability, such as it is, to intuit what other people are thinking; simple things like if Joe sees a ball put in Box A, and is out of the room when it gets moved to Box B, you know that Joe probably thinks the ball is in Box A.  It was long considered proven that children cannot imagine a false belief in another.  High functioning adults with autism may also lack this quick facility of knowing what another probably thinks or knows.

One man diagnosed with Aspergers wrote a wise and funny book called The Journal of Best Practices.  One “best practice” was “Don’t turn off the radio when my wife is singing along to it.  Simulation Theorists say “figuring it out” is too clumsy a tool to explain the speed and accuracy of most people’s “getting” what should be in anothers' mind.

At the height of the mirror neuron excitement, Goldman and Vittorio Gallese (One of the original discoverers of mirror neurons) wrote “Mirror neurons and the simulation theory of mind-reading” Trends in Cognitive Science, 1998 Dec 1;2(12):493-501. I had the opportunity to ask Goldman “Why monkeys” and he thought, well that’s just what they happened to be studying.  But 25 years after the first discovery, we have hundreds of follow-up studies of monkeys and some of humans, and no other branches of the animal kingdom.  Has even more than one species of monkey been studied extensively?  I’m not sure.  But recent experiments have shown mirror neuron activity in marmosets, whose common ancestry with Macaques goes back 30-40 million years.  This suggests a very old adaptation made by an early monkey ancestor

I’ll go out on a limb and bet that monkeys are something of a special case, and predict that close studies of monkeys traveling in groups from tree to tree (see video) will show that if monkey A is following monkey B, A will generally copy B’s way of grabbing the next branch.  We might also find that the most agile monkeys take the lead in traveling.  Jumping from a branch across several feet and catching hold of another branch high in a tree is a tricky business. I don’t know anything about the speed with which macaques or other monkeys roam among trees, but to move quickly in a group might be highly dependent on this ability.  If such an adaptation is rare or unique, it could be a key to the evolutionary success of monkeys, by which they leave behind many predators. Chimpanzees are a striking exception.  In most accounts of them hunting for food, they are hunting monkeys.  But then Chimpanzees are more or less descended from monkeys

Are monkeys very good at imitating in general?  According to Goldman, his coauthor Gallese, who studied them in labs, said “No”.  This suggests that monkeys’ motoric empathy might be little used except in treetop locomotion, so perhaps we should call it limited motoric empathy.  On the other hand, a Science Magazine article, “Capuchin Monkeys Display Affiliation Toward Humans Who Imitate Them” notes that “wild capuchin groups routinely synchronize their behavior; for example, for travel, feeding, and predator defense”.

Where am I going with this?

This article, based on various scientific and philosophical works and my own thinking, suggests a path from simple motoric empathy to empathy in the broadest sense, and beyond that to what Philippe Rochat, cited in Sarah Perry’s The Essence of Peopling, calls “Others in mind” – having, in our minds, a continuous presence of models of others, as illustrated by this image from The Essence of Peopling:

Action parsing in monkeys and humans

The skill of “reading” physical actions, not necessarily for imitating, is called “action parsing” (or action processing), a theme touched on repeatedly in The Shape of Thought: How Mental Adaptations Evolve (Evolution and Cognition) by H. Clark Barrett, and is a major topic for both neuroscientists and AI researchers.  If we knew just how action processing works, we could just show a task to a robot, rather than programming it.  This has begun to happen, but it’s taken a long time, and many iterations of Moore’s Law.  Our closest relatives, chimpanzees seem to have a high level of action parsing because they are very good at picking up techniques from one another, including rudimentary tool use, and do so much more quickly and with fewer trials than monkeys. Domesticated chimps living with humans have been able to learn sign language to a significant degree, and they seem to do a lot of communicating through hand gestures in the wild.

High expressions of how humans use action-parsing might be watching and performing a choreographed dance, or those comic routines in which one person pretends to be the mirror image of another.  Recognition that one is being imitated is more widespread than being able to imitate competently, according to the article noted above: “Capuchin Monkeys Display Affiliation Toward Humans Who Imitate Them”.  This makes sense as to imitate requires “reading” another’s action while action parsing might go on passively if there is no motive to imitate.  It might, however, provide quicker anticipation of how another might attack.

Or consider the degree of action parsing evident in this description of a hunting party from Sarah Perry’s essay What Is Ritual?
One day, deep within the forest, Agaso, then about 13 years of age, found himself with  rare good shot at a cuscus in a nearby tree. But he only had inferior arrows. Without the slightest comment or solicitation, the straightest, sharpest arrow of the group moved so swiftly and so stealthily straight into his hand, I could not see from whence it came.
At that same moment, Karako, seeing that the shot would be improved by pulling on a twig to gently move an obstructing branch, was without a word already doing so, in perfect synchrony with Agaso’s drawing of the bow, i.e., just fast enough to fully clear Agaso’s aim by millimeters at the moment his bow was fully drawn, just slow enough not to spook the cuscus. Agaso, knowing this would be the case made no effort to lean to side for an unobstructed shot, or to even slightly shift his stance. Usumu similarly synchronized into the action stream, without even watching Agaso draw his bow, began moving up the tree a fraction of a second before the bowstring twanged.
Quoted from E. Richard Sorenson, Preconquest Consciousness
While there must be action parsing, much more seems necessary for what the article aptly calls “group proprioception”, or the several boys moving like one body.

Infants train selves to be social

Much of the explanation, I believe, is summarized in 8 pages in “The Ultra Social Animal” European Journal of Social Psychology (Apr 2014) by Michael Tomasello, the briefest and most accessible overview of a vast set of research and analysis.
“The Ultra Social Animal” (tUSA) among other things, illustrates and analyzes some non-obvious aspects of how children engage in cooperative tasks.  If the task produces a reward that can be shared, children insist on fair division, and sharing only among those involved in the production; quite unlike chimps who simply grab and what they get depends mostly on how close they are to the prize, and if some bystanders are close to the prize and get some, they are no more resented than are participants.  Commitments seem to be phenomenally real to older children. “When 3-year-olds need to break away from a joint commitment with a partner, they even ‘take leave’ through some form of implicit or explicit communication—as a way of acknowledging and asking to be excused for breaking the commitment” (tUSA, p189) This suggests that being a “we” in such a joint endeavor might involve a special mental state
Another aspect noted is that often children operating in different roles are conscious enough of the others that they can switch roles with little or no evident lag in competence. Tomasello suggests we have a “bird’s eye view” of social situations.  Could some conscious or unconscious part of our minds have such a view?  Could it have anything to do with out of body experiences, in which one looks down at oneself and one’s surroundings?  Sarah Perry, in Cartographic Compression cites cognitive scientist Lera Boroditsky’s time among speakers of the Australian aboriginal Kuuk Thaayorre language.  This language incorporates what roughly amount to compass points, and a person is expected to have a sense of one’s orientation to them at all times.  Boroditsky failed miserably at this at first, but then
After about a week of being there, I was walking along, and all of a sudden I noticed that in my head there was an extra little window, like in a video game. And in that console window was a bird’s-eye view of the landscape that I was walking on, and I was a little red dot that was traversing that landscape.
Boroditsky shared the cognitive change she experienced with a native speaker of the language, who commented, “well of course – how else would you do it?”  It is noted casually that a third of human languages have such a feature.  There are approximately 6,000 identified languages, most of them spoken by small wilderness-dwelling tribes as in Australia, Papua New Guinea, and the Amazon, so this may be predominantly a feature of such cultures.  Tomasello’s “bird’s eye view” doesn’t of course call for such a literal phenomenon as an inset screen, but if the latter is even possible, the former is made more plausible.
According to Tomasello’s research, and summarized in tUSA infants begin, as early as 9 months old, to initiate their own preparation for being good collaborators.  Well before the 2nd year, infants begin to seek out “protoconversations”.  Perhaps you’ve experienced this with a stranger’s baby in a supermarket checkout line.  The baby smiles tentatively; you smile back, and the baby smiles broadly.  You may initiate some surprising but not too alarming gesture, which you then repeat the baby comes to anticipate and it is done over and over to laughs like a sort of little game.
Somewhat later, infants want to point out interesting sights to familiar adults, with the clearly desired result of a shared emotive attitude, of surprise, laughter, or maybe sometimes worry (“Uh Oh”, being one of the first things children learn to say).
In his book Origins of Human Communication (2008), Tomasello provides these examples of parents’ diary observations of infants’ pointing in the context of everyday social interactions.
  • At age 11 months, J points to the closed window when he wants it open.
  • At age 11.5 months, J points to the door as Dad is making preparations to leave.
  • At age 11.5 months, after Mom had poured water into J’s glass at the dinner table; a few minutes later J points to his glass to request that she pour him some more.
  • At age 13.5 months, while Mom is looking for a missing refrigerator magnet, L points to a basket of fruit where it is (hidden under the fruit).
As in the example of the refrigerator magnet, Tomasello’s laboratory work shows many instances of children at about this age displaying a seemingly sophisticated understanding of both the fact that someone is looking for something, and a reason why they don’t know where it is.  Recall that a false belief perception is when you know that someone else has the wrong picture of what is going on due to a missing fact or observation.

Until recently, false belief tests involved setting up a situation where X should have the wrong idea about where something is, and asking "Where will Sally look for (the ball)?".  Children fail at these verbal analytical tasks until around the age of four.  But from all the experiments I have read on infants and very young children it seems that, like nonverbal animals, they have visual reasoning, but their visual reasoning is very superior to that of animals.

One way to account for what we observe in these experiments is to suppose that from a very early age, we carry avatars in our minds, simulating simple physical experiences of other, so that a 14 month old, having observed another go outside the room when the ball was moved from Box A to Box B, can briefly replay a scene from the perspective of the avatar, not being in the room and missing the ball being moved, and as the avatar merges with the person observed, feel surprise at her  acting like she has knowledge the avatar shouldn't have.
If this sounds fantastic, bear in mind the strangeness of the fact we are trying to account for; that of 14 month old children knowing things that they will not be able to work out with linguistic thought until the age of four; in fact, it seems that linguistic thinking hinders and conflicts this early form of thinking, whatever it may be like.

“Others in Mind” when we Dream

So far, we are looking at very contingent and ephemeral social situations. A recent analysis of dreaming suggests something about ongoing relations with people we see repeatedly, and it speaks explicitly of avatars.

One of the most common theories about dreaming held by researchers is that it is necessary for turning the ephemeral memories of a day into permanent memories.  What are permanent memories like?  A naive idea might be they are like stored film clips.  The beginning of this paper dealt with a kind of memory, of who Jennifer Aniston is and what she looks like, like what we call an idea or concept, which is beyond any assembladge of snapshots or film clips.

Another sort of memory is what that valley, or the top of that hill, or the first home that you remember is like.  Turning the film clips of the day into idea-like memories, or assimilating them to existing memories would seem to require a lot of processing, perhaps with a good bit of parallelism, probably best done when the brain is “off line”, and the idea that dreams are a by-product of such a process makes intuitive sense, and might shed light on the chaotic nature of many dreams.

“The Avatars in the Machine: Dreaming as a Simulation of Social Reality” (2015) by Antii Renvonsuo, Jarno Tuominen, and Katja Valli, introduces a theory of dreaming, which I think can be related to the idea of "mind reading" as occuring, at least in infants and toddlers' minds, in the form of simulations.  The paper is part of a virtual forum organized by Thomas Metzinger, and appeared alongside papers by Daniel Dennett, Ned Block, Paul Churchland, Vittorio Gallese (mentioned previously), Allan Hobson, and Jesse Prinz.

The primary author, Renvonsuo, has studied dreaming and consciousness for two decades.
The paper summarizes a great deal of research by saying in essence that dreaming provides opportunities for trying out encounters with people in one’s life, or especially in children's dreams with beings unlike oneself.  Why do we do this?  Maybe the practice makes us better at dealing with real situations, and while we don’t remember much of our dreams, they may be shaping our ability to imagine possibilities in response to a real situation, or to respond swiftly even without consciously imagining them.

A social reality simulator would be quite an impressive thing to have evolved. It is doubtful that animals we evolved from had such a strong need of social simulation, yet unlikely that the short period of human evolution created such a thing out of whole cloth.

Would animal’s dreams have been simulating something simpler?  If animal brains could have a simulation engine, what kind of simulation engine, and how best could it serve the needs of survival?  While some animals, like snakes, seem to trigger an innate fear in various species, successful species get scattered far and wide, encountering physical environments and a variety of other animals beyond what instinct can prepare them for. Predators could benefit from an ability to form concepts (or complexes of associations) of various species, like where to find them, how to run them down, and what they do to defend themselves.  Prey animals have a corresponding need to know about predators, how to get out of their reach; how to fool them, etc.  All of this must be gained quickly from a few encounters, and it would be ideal if a few encounters could stimulate a broad repertoire of how to act when encountering them in the varieties of terrain typical of their environment, and indeed in various nooks and corners of their range.

No animal, unless it dwells in a featureless desert, or has a tiny range, like cave fish, can inherit full knowledge of its environment.  Animals,  especially w.r.t. species that prey on them, need to gain as much competence as possible from as few “close calls” as possible.  This reminds me of the requirements of a flight simulator. What if they had a simulator in which to play “war games” with antagonistic species?  If dreams can bring to mind threat or prey species, with characteristics we know by observation, and superimpose avatars of these on familiar and realistic landscapes, new response sequences can be imagined and stored away.  A squirrel is surprised by a fox and he escapes by popping into a hole.  Suppose it has dreamed of encountering the fox near this very hole, which has conditioned its nerves and muscles to make the best response.

Two suggestive bodies of evidence have developed lately. Studies of mice and rats have shown that if the shape of their environment is changed, the nature of their dreaming becomes more intense for some period, and brain areas concerned with navigation are particularly active.  Now if only the experimenters had thrown in some novel simulated predators, or new ways of acquiring food.

For the second bit, returning to Renvonsuo’s paper, one finding is that children are much more prone to dream of animals than adults, except if the adults have something like a hunter-gatherer existence, the proportion of dreams of animals remains high.  This would be consistent with a recent adaptation of the role of dreaming from mostly elaborating and perfecting ones inter-species responses to very largely perfecting ones social interactions with other humans.

In recurring dreams, we often face the same people, or for children, the same monsters repeatedly.  If these represent avatars, then might an avatar of, say your mother, brother, boss, or spouse be a sort of permanent fixture, that hangs around from night to night, helping you refine attitudes and responses to these people?

Might it turn up in the daytime?  Have you ever had an imagined argument, often a rehash of a bad, mad conversation, that just keeps playing and you can’t stop it.  You try to improve on a dumb response, and they come back with something else, and then you say whatever and then they say whatever, all pretty much in character (or our flawed version of the other’s character).  I know I have.  Anyone else?  People on the autism spectrum, Yes or No?

Dan Sperber is a cognitive scientist who thinks and writes more like a philosopher. In 1986 he wrote, with Deirdre Wilson, Relevance: Communication and Cognition. In effect, it says when we communicate with a person (one whom we know), we don’t simply “send a signal”.  We know as we bring the listener to mind what is relevant  to them and what is not.  We may know that in the context, a single word, or glance in a certain direction may be all it takes; and we act accordingly, usually without any consciousness of doing so.

When we communicate with someone, do our communications go by way of the avatar, whose mind we can read because it is inside of our mind, which is a simplified model of the person we're speaking to?  And is this avatar the same, or at least continuous with, what we get when we happen to dream of that person?

Peer to Peer: Implications and Further Directions

The way humans seem designed to interact, and create action and knowledge seems to me very much like a sort of peer-to-peer protocol — for combinations of people in roughly equal relationship; not a protocol for one to control many.  As Venkatesh Rao wrote in  Your Passport to the Meta-brain (Breaking Smart Newsletter), “In the non-exclusive mutual containment metaphor, however, each of us exists as both a living conscious being, and as an evolving digital ghost presence that others can include in their second brains.”  We seem designed for free agent collaboration.  Our sociality and our individuality are equally necessary. Infants take their own initiative in learning the social skill of language and in teaching themselves to be social.

We are by nature curious and driven autodidacts, but this produces a restless energy that educators have hardly ever known how to channel.  I would argue, given more space, that the Khan Academy’s methodology is far more suited to model of humanity I have been developing here.

Most evidence indicates the hunter-gatherer societies in which our nature took shape lacked extreme dominance.  A settlement typically had something anthropologists call a “headman”, but he generally needed a lot of persuasion and sometimes yielding to the prevailing sentiment, rather than issuing diktats.

 The potential for the “alpha male” typical of chimpanzee society didn’t disappear from our natures, but reemerged with a vengeance on the heels of the ultimate disruptive technology: agriculture.  Early agrarian empires, at least in Mesopotamia, South and central America, and China, all seemed to pass through a horrendously cruel phase.  James C Scott’s recent work: Against the Grain: A Deep History of the Earliest States partly dealing with barbarian cultures having long parasitic, and fairly happy (for the barbarians) relations with such civilizations might provide some insight.  Early agrarian societies were tied to a place, rapidly growing in population, too big for headman/consensus governance, and piling up surplus that made them the inevitable target of  less sedentary tribes.  The experience of war with its necessity for acting en masse, preferably with the unpredictability that a single dominant secretive mind may have led to the predominance of such relations,  continuing more or less until the time of emergent democracies.

Ever since the acceleration of technology reached a certain point, the superior creativity of more peer-to-peer-ish societies tended to prevail, but in recent decades, a great many non peer-to-peer societies have literate elites capable of gathering technological power that they could not have created, and these elites often become parasitic.

While much writing on the “singularity” is foolish, we do seem headed towards a very big, strange, and accelerating unknown.  We are experiencing something like the Gutenberg revolution which helped unleash two centuries of religious wars, but we are experiencing it in more like two decades.  In a torrent of disruptive changes, including those that might put the ultimate destructive weapons in the hands of the least wise and balanced, it seems very unwarranted to think we know how it will turn out, and the fact that so many have a definite prediction may reflect one of the native imperfections of the human mind.  Just to give one example, genetic engineering could reach a state where any unbalanced but highly intelligent fool could design an “ultimate” virus, capable with the right dispersal methods of wiping out a population in days.  The same technology should in theory provide the means of quickly analyzing and stopping such a virus, but it won’t matter if we have a failure of imagination and are oblivious to such possibilities (and if I thought I could think of all such risks I’d again be foolish).

Many threats are analogous to the virus example; we have races between dangers and remedies, both accelerated by Moore’s Law and a knowledge explosion.  If we are to reach a happy rather than nightmarish version of living in the meta-brain (Venkat, Breaking Smart Newsletter), or whatever the future looks like, this model, if correct might be one necessary addition to our toolkit.

Evolutionary biology is slowly becoming relevant to human social problems.  If evolutionary psychology seems stuck at “Just So Stories”, I believe, in time, it will become unstuck. Within a decade, we could make real progress in understanding how the genome produces the developmental process out of which humans are formed, and such an intimate knowledge of the genome, and a refactored way of seeing it should reveal more about our mental and social development, and what parts are built on what other parts (Sean B. Carroll in The Making of the Fittest gives interesting examples of this) and allow us to define more operationalized versions of human social and other qualities.  We are somewhat at the stage where we call anything that swims in the sea a fish, whereas deeper knowledge tells us there are fish and cetaceans, totally different from one another.

Tuesday, March 13, 2018

The Knowledge Producing Enterprise: New Official Intro

The phrase "knowledge explosion" usually refers to "what is known" in some abstract sense, as if there was an official (World) Storehouse of Knowledge (WSoK). The question of whether I know, or you know, or how many people know a thing hardly registers.

Many attempts to explain the "knowledge revolution" involve exponentially rising graphs, perhaps of academic journal pages, or or everything published to date, or in recent days, the total number of words on all the pages on the web, glossing over the fact that much content on the web isn't static, but potentially unlimited combinations of content from a back-end database. But surely not everything that is published, or written on a web page, is "knowledge". To my mind only a tiny fraction could possibly deserve to be called knowledge.

Partly to answer such questions, there is a philosophical discipline called epistemology, or "The study of the nature of knowledge, justification, and the rationality of belief." Another question an epistemologiest might ask is "If one person in some discipline has arrived at some correct conclusions, such that a decade from now everybody will know he was right, while the other hundred people in their discipline think the opposite can we say 'it is known', or it belongs in the WSoK?"

Monday, March 12, 2018

Science in a Nutshell: From Projectiles to Invisible Elephants to Plate Tectonics

Science in a Nutshell: From Projectiles to Invisible Elephants to Plate Tectonics

For our pre-technical ancestors, the clockwork at the bottom of the material world was so clothed in messiness that hardly a trace of it appeared on the surface.  But you could say that three exposed bits collectively formed a Rosetta stone to the mathematical language of nature:  a thrown rock, a pendulum, and the solar system, revealed by the night sky.  The last had to be viewed from such a difficult angle that reams of tables, centuries worth of exact observations, and a huge advance in mathematics were required to see it, but it was there to be seen.

Clockwork Model of the Solar System, source: Wikimedia, Creative Commons 20

Saturday, September 9, 2017

The Knowledge Producing Enterprise: Old, Verbose Intro

Old, Overly Verbose Intro to this blog, but with some account of how I got here.

Mma Ramotswe, heroine of the No. 1 Ladies’ Detective Agency novels has an annoying habit of prefacing sometimes controversial statements with “It is well known that…”.  Epistemologists (philosophers of knowledge) for centuries had an annoying habit of treating “It is known” or some equivalent as the only distinction worth making w.r.t. truth and knowledge.  Not whether I know or you know, but seemingly just the abstract notion of whether a given justification for a proposition really, really qualifies it as knowledge.  Whether one person or a million know X is not a matter for discussion.  Anyway, the chances are if a million people “know” something, they don’t know it in a philosophically justified way, so if asked  how many Americans know that Barack Obama is a U.S. citizen, they might say hardly any.  Social Epistemology offers some promise of rising above this dilemma, but surveying where it is today, I don’t see it happening.
My opinion is there may be little practical benefit to discussing knowledge in this way.  Maybe the very idea of discussing or studying knowledge is the problem.  Maybe the difficulties of advocates of rationality or critical thinking are due to this focus on this strange thing called knowledge - a product of the “view from nowhere”, which tends to break down in the social domain.