In Praise of Friction and Misunderstanding

What friction is, and why it's slippery

Stage one: working around friction

The wheel is the obvious starting point. Rolling reduces friction because a rolling object touches the surface at far fewer points than a sliding one. But Vail stresses that the wheel also depends on friction. When you push a wheel, static friction between it and the ground stops it from spinning freely. Once it is moving, dynamic friction does the same job. Ice shows what happens when there is too little of either.

Solving one friction problem tends to expose another. Roman chariot racers dealt with axles that heated up through wheel-on-axle friction. Horace's Odes describe chariot wheels glowing during races, which is motion turned into heat. Builders greased the joint with axungia, animal fat. This drew on a lesson the Sumerians already knew: fats and oils lubricate better than water. But hot grease can catch fire, so crews threw water on the wheels to cool them. Vail compares this to a modern pit stop.

Stage two: measuring friction

In Vail's account, the 20th century was when friction became something engineers could measure and design around. In the 1920s Chrysler's head of engineering, Carl Breer, wondered why cars couldn't move through air the way planes did. He sent engineer William Earnshaw to consult Orville Wright on wind-tunnel testing. The result was the teardrop-shaped Chrysler Airflow of the 1930s. It sold badly because buyers found it too strange. Vail argues that it still changed car design, since wind-tunnel testing became standard. Tribology labs now operate across the car, medical and food industries, measuring friction from large machines down to the atomic scale.

The extremes have pushed new materials. Vail's own specialty is solid lubricants for jet engines and cars, where grease would burn. In some of her tests, the steel rubbing against her samples heated up enough to change colour.

Stage three: using friction

Vail is most interested in the 21st century, when she says researchers began using friction as a tool and not only fighting it. Her examples cover very different fields:

The argument underneath

Vail's broader claim is that resistance shows up because of progress. The solid-lubricant industry exists because people built turbine engines, which exist because people learned to fly. She applies this to her own work: if she is stuck, it is because she has reached a point where that particular resistance appears. She quotes William James on life being built "in the self-governing resistance of the ego to the world." She ends with the image of a wheel spinning in place: ease with no resistance is motion that goes nowhere.

What to make of it

The engineering history is solid and full of good detail. The trade-off examples are the strongest part, because they show that "reduce friction" is never the whole design brief. The step from physics to "resistance is your reward for progress" is a metaphor, and Vail doesn't really defend it against the obvious reply. Much of the friction people want out of checkouts or paperwork is pointless delay, not traction. Her case would be sharper if she said which kinds of friction are worth keeping.

The feeling is familiar. A friend describes their day and you nod. A stranger on a platform shares a weary glance as the train pulls away without you both. In moments like these, it seems as though two minds are holding one thought. Our language says so: we "think the same", "know what's on someone's mind", "get our thoughts across".

In an essay for Psyche, the philosopher Víctor Verdejo argues that this picture is old, powerful and misleading. Understanding someone, he suggests, often involves thinking differently from them, and seeing why changes what we should expect from conversation.

A long tradition of thought-sharing

The idea that communication moves thoughts from one mind to another goes back a long way. Plato placed the ideas behind our knowledge and speech in a separate realm of unchanging, perfect forms, a foundation everyone draws on. Augustine of Hippo, writing in De doctrina Christiana (397–426), described signs as tools to "transmit to another's mind what is in the mind of the person who gives the sign."

The version that shapes our intuitions today, Verdejo says, comes from John Locke. In An Essay Concerning Human Understanding (1689), Locke held that the point of language is to be understood, and that words fail "when any word does not excite in the hearer the same idea which it stands for in the mind of the speaker."

Where the picture breaks

Verdejo isn't mainly interested in plain miscommunication. His point is that even when communication succeeds, the thoughts on each side often fail to match.

His first example: you tell him irritably, "I had an awful day at work," and he replies, "I see." In one sense he understands you perfectly. But your thought is rich, full of frustration and the details of everything that went wrong, and the exchange doesn't require him to take all of that on. Even if you told him every detail, something would stay yours: it's your job and your frustration. Sympathy doesn't make it affect him the way it affects you.

The second example, which Verdejo takes from the philosopher John Perry, is sharper. You and a hiking partner are in the mountains when a bear approaches them. They shout, "A bear is about to attack me!" You understand at once and run for help, while your partner curls into a defensive ball. If you had literally shared their thought, including its sense of an imminent threat to oneself, you would have curled up too. Your understanding worked because your thought was different: theirs was "I am in danger", yours was "they are in danger, and I can help."

Two ways to rebuild the idea

Verdejo describes two current responses in philosophy.

Layered thought-sharing. This is the view Verdejo himself favours. It keeps the idea that two people can share a thought but treats each person's version as layered. Some core content or mental state has to be identical for the thought to count as shared, while other layers differ to reflect each person's point of view. In the bear case, the shared core might be roughly a bear is about to attack this hiker; the perspective layer (me versus them) differs. Verdejo argues this keeps something useful. It lets us tell apart misunderstanding someone ("getting the wrong idea") from understanding them and disagreeing ("getting the idea" and rejecting it). That distinction needs something both parties have grasped. As he puts it, sharing thoughts is complex because thoughts are complex.

An analogy may help (it is ours, not the essay's). Two dancers don't need to make identical moves. They need moves that fit together. The layered view says some steps must be the same; relationism says fitting together is all there is.

Verdejo notes that the debate between these camps is unresolved. Both, though, reject what he calls the tempting assumption of a perfect match between minds.

Why it matters outside the seminar room

Verdejo ends on a practical note. Mutual understanding is real and makes a common world possible, beyond our private experience. But difference is part of it too, so we shouldn't expect understanding to produce one single, shared experience. Knowing this, he suggests, could head off frustration and overoptimism. It might also bring more patience, more readiness to restate and elaborate "in order to build the shared kernel of our differing thoughts," and some acceptance when someone doesn't quite get it. Sharing anything beyond superficial or abstract thoughts takes time and effort, and sharing everything is impossible. "But that is exactly as it should be," he writes.

What stays open

The essay is short and doesn't settle the hard questions. It doesn't say how large the "core" must be on the layered view, or how anyone could tell whether two cores are identical. It also doesn't say how relationism explains the difference between disagreement and misunderstanding without some shared content, which is the very point Verdejo uses to favour his own view. Readers who want the technical arguments will need to go to Fine, Perry and Stalnaker directly.

In 1999 a stranger rear-ended Clark Elliott, a professor of artificial intelligence at DePaul University, at a stoplight. He drove to work thinking he was fine. He was not, and the injury shaped the next ten years of his life. The Ghost in My Brain is the memoir he built from notes he took while concussed. An anonymous finalist in the 2026 Astral Codex Ten book review contest reviews it. The reviewer had a serious concussion of her own about a year and a half earlier, and she admits she read the book hoping for a cheap fix. What she found instead was what she calls "the weird borderlands of modern medicine."

A broken mind that can't see its own breaks

Elliott's symptoms are hard to picture. After a long workday he needed more than an hour to cross a parking lot, then stood by his car for another hour and a half because he had "lost the concept of center" and couldn't guide his key into the lock. He got home at 3:30 a.m. He could write but not read. He could climb stairs but not go down them. He could teach a graduate seminar and then fail to recognize his own house on the walk home. One day he could not choose between eating a piece of salami and an apple first. He walked between the kitchen and the living room ten times, and two days passed before a friend on the phone told him: salami, then apple.

The reviewer stresses one point: the faculties that would notice these failures were themselves offline. After the crash, Elliott handed his license to the other driver twice and had no memory of the first time. In his words, lost capabilities are "so fully gone that the concussive does not miss them."

The recovery

The reviewer is openly baffled by that last step. Zelinsky's claim is that faint light through the eyelids still stimulates the retina, and the lenses change how it spreads. But eyelids pass well under 1% of blue-green light and only about 5–6% of red light, which is diffuse glow, nowhere near enough to locate a bell. Even so, within a year Elliott had largely recovered. When he lost his glasses for 33 hours he slid back into exhaustion, worse handwriting and visual problems, and he recovered once he found them. Fifteen years after the crash the recovery had held.

Weighing the evidence

The scientific case is thin. A 2016 meta-analysis of 14 studies found a small benefit from cognitive training after brain injury in general, but Markus's own method has only a 2007 "how I do it" write-up behind it. The one study of the Z-bell method is a 2019 conference paper whose first author is Clark Elliott. It reports 14 of 41 recruited participants. The therapeutic lenses beat clear lenses by a small margin but did no better than an "impaired lens" meant to make performance worse, and the full study was never published. The reviewer also lays out the skeptic's case: Elliott was desperate, he finally had attentive clinicians, his treatment was adjusted gradually over years, and some chronic cases recover on their own.

Where averages fail

Her verdict on the book: frustrating as a roadmap, since Elliott accepts his clinicians' explanations too readily and treats his own path as more general than it is, but excellent as a first-person account of what it feels like when a brain breaks.

The essay is less about any single supplement than about how a careful person persuaded himself of something.

The original argument

The starting idea was reasonable. There's no special reason to expect a normal diet to supply the best amount of every micronutrient (vitamins and minerals) and every phytonutrient (beneficial compounds from plants). The ideal amount might sit well above the level that merely prevents deficiency. With good enough evidence, he thought, it was worth taking a punt on:

He also held detailed opinions about which supplements were dangerous (copper), which were pointless (most B vitamins except B12, and creatine for people who eat meat), and which were essential.

The three-part test

He judged a supplement worth taking if three conditions held:

1. An evolutionary story. Humans evolved eating more of the nutrient than modern diets supply.
2. A mechanism. There is a logical, not obviously disputed explanation of how it works in the body.
3. Evidence. Higher intake at least correlates with better health. Ideally, well-designed trials show that it causes better health.

Vitamin K2 shows how this worked in practice. The evolutionary story: modern diets contain less liver, alpine cheese and grass-fed butter, which are traditional sources of K2. The mechanism: K2 is thought to help keep calcium out of artery walls, and the worry was that high-calcium diets would otherwise cause arteries to calcify. The evidence: adults with more K2 tend to be healthier, and some academic studies report benefits. All three conditions seemed to hold, so he bought a specific brand chosen for what he judged the right ratio of the rarer menaquinone-4 to the more common menaquinone-7.

Why it fell apart

He says the method was bad and that he applied it badly.

The three-part test made this easy. An evolutionary story can be invented for almost anything. Plausible mechanisms are easy to find. Supportive studies exist for most claims if you go looking for them.

Problem two: most of the evidence is weak. Ritchie and his colleague Saloni Dattani had long told him that science is "overloaded with complete nonsense." He agreed with them in principle but still assumed that a big enough pile of papers would point the right way. He now believes "something like 90 percent of research is nearly valueless."

What the essay doesn't settle

The author says plainly that ordinary meat-eaters may sometimes benefit from a supplement. His claim is narrower: his own method couldn't reliably tell which ones. The essay gives no new data. It doesn't re-examine the trials on K2, fish oil or glycine, and it doesn't say how to tell the roughly 10 percent of useful research from the rest. It is an account of changing one's mind, and it ends by conceding the argument to Ritchie.

The problem: what to do when the ground goes

Popova starts from an experience most people have at some point: losses "beyond our control" that leave us "bereft of solid ground." The usual responses are to fix the problem, to distract ourselves, or to find something solid to hold on to. Chödrön's book drew on her own personal crisis. Popova doesn't describe that crisis, though it is widely known to have been the end of her marriage. The book's claim is that all three responses get in the way of what a crisis can teach.

Popova puts this beside two earlier lines. Kafka told a young friend that "in art, one must throw one's life away in order to gain it." Camus wrote that "there is no love of life without despair of life." Chödrön, in Popova's reading, takes the same idea out of literature and into practice.

Step one: fear is not the enemy

Chödrön starts by making fear ordinary. "Even the smallest insect feels it," she writes. Touch a sea anemone in a tide pool and it closes. Fear, she says, is "a natural reaction to moving closer to the truth." It is not a sign that something has gone wrong.

From there she redefines bravery. Bravery isn't the absence of fear. It is intimacy with fear, and that intimacy is the tool: "If we commit ourselves to staying right where we are, then our experience becomes very vivid. Things become very clear when there is nowhere to escape." She expects this to keep humbling us, because it strips away "the arrogance that holding on to ideals can bring." Her phrase for it is "the courage to die continually," meaning the repeated letting go of how we think things should be. The line Popova uses as her epigraph sums it up: "Only to the extent that we expose ourselves over and over to annihilation can that which is indestructible be found in us."

Step two: nothing gets solved

The second move is a claim about how life is structured. "We think that the point is to pass the test or to overcome the problem, but the truth is that things don't really get solved. They come together and they fall apart." On this view healing isn't the point where trouble ends. It is "letting there be room" for grief, relief, misery and joy, all of them, as they come and go.

The tools: maitri and ye tang che

Two Buddhist terms carry the argument.

Theism without God

Chödrön's instruction follows from it: "Begin the journey without hope of getting ground under your feet. Begin with hopelessness."

From self to others

The essay ends by turning outward. Self-compassion toward one's own darkness, Chödrön suggests, is what makes real care for others possible: "We don't set out to save the world; we set out to wonder how other people are doing and to reflect on how our actions affect other people's hearts."

What to weigh

The essay is a guided tour of one book, not a critique, and readers should take it that way. Popova doesn't test Chödrön's claims against other views. That includes therapeutic traditions such as acceptance-based therapies, which also ask people to make room for pain instead of fighting it. She also doesn't ask whether "begin with hopelessness" is safe advice for someone in clinical depression, as opposed to someone going through grief or upheaval. The word "hopelessness" is doing specialized work in the book. It means dropping the hope of escape, not despair about life, and the essay depends on readers keeping those two apart. Its real value is the reframing. It treats being unsettled as the main place where clarity can happen, not as a detour from a good life.