The marathon, the algorithm and me

Twenty-five centuries ago, after the Greeks shattered the Persian army at Marathon, brave Pheidippides ran 26 miles to Athens with the news. Robert Browning’s poem tells the tale:

“Rejoice, we conquer!” Like wine thro’ clay

Joy in his blood bursting his heart, he died — the bliss!

With the death of Pheidippides began the legend of the marathon, a feat of running so arduous that the very attempt could kill you. I plan to run my first marathon in April in London, hoping to avoid his blissful fate. After all, I have an ally that he did not. Pheidippides, for all his valour, lacked a sports watch.

I was never a runner; my knees weren’t up to it, I’d tell myself. But one thing led to another and, after a couple of years at my local Parkrun, I bought an entry-level running watch, with no aim beyond pacing myself evenly. I didn’t realise that I was plugging my body into the exercise yard of the digital panopticon, with the watch’s app estimating everything from my heart-rate to my step count, and hazarding a guess at my body’s capacity to use oxygen, not to mention my “fitness age”. I had never dreamt such a small box of tricks could provide so many numbers, all claiming in some way to — and here I quote the watch manufacturer, Garmin — “support your efforts to improve and maintain your health”.

There is no denying the technological cleverness here. My watch uses a network of 24 satellites, time signals to within three billionths of a second and calculations adjusting for the irregular shape of the planet in order to pinpoint my location to within 5m. It adds an accelerometer, a device that detects changes in speed or direction using interleaved combs of conductive material etched on silicon that flex and touch as my wrist moves. A strip of flashing green lights on the underbelly of my watch monitors my heart rate by detecting how much light bounces off my wrist rather than being absorbed by the red blood swelling and shrinking my tiny capillaries.

It is all something of a miracle, but more interesting still is the panoply of behavioural nudges, everything from inviting me to share my runs on social networks to tracking my “streaks” of exercise. Last year, I began training for a 10k race, then a half-marathon (more than 21km), using the free coaching software bundled with my watch.

Over 12 weeks of training, my virtual coach would send me off on several runs a week, gradually sharpening the pace and increasing the distance, mixing things up with easier runs or fierce sprint intervals. From time to time, I’d get a short article or a canned video message and, after every run, an upbeat verdict: “Great job!” or “Room to grow.” A coloured dial, purportedly indicating my coach’s confidence, but actually the output of some unknown algorithm, told me how likely I was to achieve my goal on race day.

Without a doubt this coaching programme worked; it prompted me to exercise regularly, and I became faster and fitter. But the longer I used it, the more questions arose in my mind.

There is something about the fitness watch that feels unnervingly familiar after two decades of smartphones and social media. An amazing technology flipping from unimaginable to indispensable almost overnight; the endless tracking, nudging, sharing; the datafication of something that previously had eluded measurement; and a sense of mystery about where all this data is going and how it is being used. On top of all that is something new and visceral: a device worn on my skin, measuring blood, breath, speed and sleep.

Is the fitness watch really to be trusted with my fitness? And can it teach me a lesson about the way so many parts of my life have been transformed into numbers, rewards and targets?

*

Automated fitness tracking began before I was born. In the 1960s, worried that their Japanese compatriots were becoming sedentary, a doctor named Iwao Ohya and an engineer named Jiro Kato developed a simple step-counter. They called it the manpokei or “10,000 stepmeter”. There are various origin stories for the figure of 10,000 and all of them acknowledge that there is no scientific logic for the threshold. That didn’t stop the idea catching on in a big way in the 21st century, when smartphones and fitness trackers began to number our steps and tut disappointedly whenever we missed their arbitrary target.

These tuts make a difference: Katy Milkman, a professor at the Wharton School and author of How To Change, showed me step-tracking data from an unpublished study. Her study subjects walked a variety of distances, but the data displayed a huge spike just beyond 10,000 daily steps, evidence of the powerful urge to satisfy the fitness tracker’s meaningless target.

Still, motivation is motivation. “There is a widespread perception that fitness trackers don’t work, which is incorrect,” says Carol Maher, a professor of population and digital health at the University of South Australia, who has conducted many studies into the effects of fitness tracking. “When you put all the evidence together, it’s very clear that they do help people walk more and take more steps. It’s a modest change but even modest changes are very beneficial.”

Maher and a team of researchers conducted a wide-ranging review of different studies of fitness trackers, covering 164,000 participants. They found all the effects that one might hope for: people tend to be more active, walk more, lose fat, lose weight and gain fitness.

This should not be a surprise. Fitness trackers set us simple goals, record our progress and share our achievements with our friends. All of these behaviour nudges are calculated to prod us into action.

Milkman sent me a short reading list of relevant studies, along with a rapid-fire summary. “Reminders change behaviour,” she told me. “Bite-sized, short-term goals change behaviour and round-number goals are particularly helpful. Self-monitoring changes behaviour. Symbolic rewards like badges change behaviour. Social accountability, such as sharing your exercise, changes behaviour.”

Both Milkman and Maher are convinced that fitness trackers help, and so am I. But help who? And to do what? It’s one thing to coax a couch potato to get up and go for a walk; it’s another to guide an ageing writer to his first marathon. Yet I had put my watch in charge of reaching this all encompassing goal.

*

At the heart of the matter is a piece of human behaviour identified by Milkman in a study conducted with behavioural scientists Linda Chang, Erika Kirgios and Sendhil Mullainathan. The researchers asked a simple question: “Do we decide differently when some dimensions of a choice are quantified and others are not?”

The answer emerged loud and clear from a series of experiments: yes, we do. Whenever experimental subjects were offered a choice between two options, they would tend to favour whichever option looked better on numerical measures and overlook qualities that were expressed as graphical elements, letter grades, star symbols or in words (“moderate”, “excellent”, “highly likely”). This was true whether the choice was between hotels, job applicants, conference locations, public works projects, restaurants or charitable causes. Numbers loomed large. What was quantified, got attention.

This matters because fitness trackers purport to excel at quantifying some things and do not pretend even to quantify others. If quantification fixation applies, we would expect to see such trackers systematically pushing people towards the quantified behaviour at the expense of other things.

An early hint of this came in 2016, when the results of a study of weight loss in 470 people were published. All these people were trying to lose weight, all of them were prescribed a low-calorie diet and all of them were encouraged to exercise. Only half of them, however, were given fitness trackers. To the barely concealed glee of journalists, who love a counter-intuitive finding, the results of the study showed that, after two years, the people who had lost more weight were the ones without the fitness trackers.

Subsequent, larger studies strongly suggest that fitness trackers do not usually hinder weight loss, but the surprising and disheartening finding is an example in miniature of the quantification-fixation problem.

In this case, both groups were equally active, but those using a fitness tracker were getting automatic, effortless validation of their effort, which they could then use to justify more indulgent eating. The lead researcher, John Jakicic, speculated at the time: “People would say, ‘Oh, I exercised a lot today, now I can eat more.’ And they might eat more than they otherwise would have.” Calorie counting is joyless, easily fudged — and not automated by the watch.

We’re all familiar with the tendency to be virtuous in one aspect of our behaviour, then let ourselves off the hook somewhere else — choosing a healthy salad, then using it as permission to order dessert. Psychologists call this behaviour “self licensing” and fitness trackers encourage it by supplying us with asymmetric data. We are told how much we moved, but not what we ate. We get stark feedback on heart rate and step count, but the tracker looks the other way if we order french fries and a glass of beer.

Here’s another instructive example of the way quantification can lead us astray. In a small experiment conducted by Rob Copeland of Sheffield Hallam University, some volunteers were asked to hit the timeworn target of 10,000 steps a day, while others were told instead to take three brisk walks a day, each of about 10 minutes. One of these exercise regimes requires a wearable computer; the other, nothing more than a pair of shoes. Three brisk walks aren’t close to 10,000 steps; in total they are more like 3,000 — not that anyone is counting.

When Copeland studied fitness-tracking data from all the volunteers, he found that those who had done the human-centred exercise of a few short walks had actually done almost a third more “moderate to vigorous” physical activity than the ones grinding out a step count for the algorithm, and found the task less of a chore.

Even on the narrow grounds of cardiovascular activity, the unquantified walk beats the quantified one — and that is before we take into account the benefits of a chat with a friend or the feeling of the wind in your hair. The fitness tracker will handle quantity all day long. But the quality of a walk? That’s up to us to defend.

Our digital devices are quantification machines. Try to count 10,000 steps as you go about your day and you’ll drive yourself mad, but your watch will do it for you without you even noticing. But what gets counted isn’t always what counts.

A brutal callisthenics session in the gym may leave me feeling that I’ve given everything, but the watch sees only my heart rate and is unimpressed. My Taiji practice is a form of gentle exercise that I greatly value, but as far as my watch is concerned I’m not really exercising at all. None of this would matter much if quantification fixation didn’t exist, but it does. It is human nature to take the watch and the activities it quantifies more seriously than they deserve.

*

Over the past 18 months, my virtual coach has paced me to my longest runs and my fastest runs, prodded me to pull on my running shoes and head out the door even when I didn’t feel like it, and broadened the (admittedly narrow) horizons of my training routines. But it has also nudged me into some decisions I regret.

Last winter, I went out running when some of the roads were covered in sheet ice. I avoided mishaps by gingerly picking my way over the obstacles, only to find the algorithm grumbling that I had not run fast enough.

A month ahead of my first flat 10k race, I picked up a minor injury. A coach would have told me to rest and heal, but I worried that the algorithm’s “adaptive” training plan would be derailed if I didn’t keep going. (Many of these training plans call themselves “adaptive” but I have yet to find one that explains how this adaptation works.)

In the end I resolved the tension between my need for recuperation and my desire for a personal best by going to my local park three weeks before race day, gritting my teeth and running the PB I’d been aiming for. Then I switched off the training plan so that I could heal. I doubt I would have achieved the PB without the watch — but I also would never have behaved so oddly.

There’s a word for losing sleep because you’re worried about being judged by your sleep tracker: “orthosomnia”. I’m lucky enough not to worry much about my sleep, but I do worry about my running. It’s easy to see how the powerful lure of a training plan that understands neither ice nor injury could prompt me and others like me into counter-productive overtraining — even permanent damage.

Some of these risks come from poor product design. Garmin’s Connect app, for example, prominently celebrates “streaks” of exercise, meaning the number of consecutive days in which I’ve recorded some kind of activity. Yet any coach will tell you that rest days are vital, so it is strange that my main fitness app applauds me for the number of consecutive days in which I have failed to take a rest.

Other risks are more subtle. When I signed up for the Runna app, for example, it suggested what seemed an absurdly aggressive target for my first marathon time — almost an hour faster than Garmin’s race prediction. The first training run the app proposed was at a blistering pace.

I spoke to Walter Holohan, the chief technology officer of Runna, who was keen to emphasise that the Runna training plan was personalised and it would use a proprietary algorithm to adapt the training schedule to my performance. Could he share any details?

“Obviously, we wouldn’t want to share our proprietary algorithms,” he explained. Obviously. I’ve not yet found a company that will. But that leaves users taking things on trust.

“It’s understandable, of course, because they’ve got competition between one another,” says Joe Warne of the Sports Science Replication Centre at Technological University Dublin. “They don’t want to share their secrets of how they’ve arrived at these values. But the more that we continue to do that, the less that we’re going to have any real insight.”

Given that the history of fitness trackers begins with someone picking 10,000 steps because it’s a nice-sounding round number, the lack of transparency and independent verification of these apps and devices is not wholly reassuring. They are not being sold as medical devices, so regulators do not get involved. I am often told that older runners need more time to recover between each run, so I asked Runna’s Holohan to reassure me that Runna would take into account the fact that I was 52 years old. Alas, he could not. Age-adaptive plans were still on the drawing board, he told me. So were training plans that reflected the menstrual cycle of female athletes.

Reassurance was no more forthcoming from Garmin. The company wouldn’t make anyone available for an interview, and ducked every question about whether the Garmin training recommendations took into account my age.

Facing a marathon, then, which app should I choose? I respect their behavioural savvy and would expect any of them to tug my strings like an expert puppet master, but I am less confident of the physiological science behind their recommendations, as their methods are secret and their pretensions to rigour largely untested.

I don’t mean to be ungrateful: my inexpensive Garmin watch and the free coaching app that was bundled with it took me from weekly wayward 5k runs to a well-paced half-marathon. But perhaps I have come to expect a little too much from my silicon coach.

Iefore my half-marathon, my Garmin app told me my predicted time was 1hr 54 minutes and 56 seconds. Strava, looking at exactly the same data, told me I could go a full 11 minutes faster. Even over a distance of more than 21km, 11 minutes is a huge difference. This put me in a quandary before the race. Everyone warned me not to go off too fast — but given the yawning gap between the algorithmic forecasts, what did “too fast” even mean?

“If you spoke to two different humans they might do the same thing,” says the digital health expert Maher. “It’s easy to believe that technology just has the answer.”

A fair point. I’d never tried to set a half-marathon time before, so any forecast would be little better than a guess. Yet that did not stop both Strava and Garmin making their race predictions to within the nearest second. And it did not stop me taking both of them seriously, and hesitating when they contradicted each other.

*

It is a sobering experience to stare at a marathon training plan.

Monday — Strength Training — 30 minutes

Tuesday — Fartlek (“speed play”) run — 10 minutes @6:05/km. 8 mins @5:35/km, 2 mins easy. 5 mins @ 5:15/km, 90 sec easy. 4 mins @5:10/km, 90 sec easy. 3 mins @5:00/km, 90 sec easy. 2 mins @4:50/km, 90 sec easy. 1 min @4:35/km, 90 sec easy. 10 mins @6:05/km

Wednesday — Easy Run — 45 mins @6.05/km, 15 mins @5.45/km

Thursday — Cross Training — 45-60 mins

Friday — Strength Training — 30 mins

Saturday — Threshold Run — 15 mins @6:05/km, 5 x 5 mins @5:05/km with 1 min rest after each, 15 mins @ 6:05/km

Sunday — Long Run — 120 minutes @6.05/km

That’s week one. It would be an oversimplification to suggest that the following 15 weeks are the same, but further and faster — but not a grotesque one. Although such a training block isn’t easy, it isn’t complicated either. With your fitness watch on and the training schedules programmed in, just pull on your shoes, head out the door and follow the watch’s orders.

But the longer I have followed this sort of plan, and the more I spoke to people in the world of fitness trackers, the more I feel that there is something missing — something unquantifiable. Serendipity, perhaps? Variety? Playfulness? Look again at that Tuesday “speed play” session. Speed, yes. But there is nothing playful about it.

These training plans are relentless and not just in the obvious fashion, where a 52-year-old body with niggles and twinges and the occasional 14-hour work day faces an implacable silicon coach which refuses to negotiate. My physiotherapist shook her head in exasperation when I told her I was planning to use the Runna app for my marathon preparation. Having seen too many people allow an app to overtrain them into injury, she urged me to think again.

But the relentlessness comes in another guise, too. It isn’t just the grind and the risk of injury, but all the times I passed up opportunities that the watch and the training plan could not quantify — opportunities to run with a friend or my wife or my informal local running club. The watch tends to have other plans, and I do not want to disappoint the watch. That is the nature of quantification fixation.

As I reflected on these missed opportunities, I realised that running apps could, in principle, set us a very different kind of training programme.

*

In 1976, David Bowie fled to West Berlin. Beset by legal troubles, drug abuse and a disintegrating marriage, he later recalled, “It was a dangerous period for me.” In the shadow of the machine gun nests along the Berlin Wall, it seemed an unpromising place to make a record. But Bowie had a way of finding new challenges and constraints, which may be why he asked Brian Eno to join him.

Eno began showing up at the Hansa Studios with a selection of cards he called Oblique Strategies. Each card had a different, often baffling instruction:

Emphasise the flaws

Only a part, not the whole

Change instrument roles

Eno would draw a single card at random, and push the musicians to respond. They did not necessarily approve of his randomised provocations — “This experiment is stupid”, complained guitarist Carlos Alomar — but it is hard to argue with the results: two of the decade’s most critically acclaimed albums, Low and “Heroes”.

Years later I asked Eno what the idea of these cards was supposed to be. “The enemy of creative work is boredom,” he told me. “And the friend is alertness.” The random inscrutability of the cards kept generating new situations and new problems. And, as a result, pushed the musicians into situations that could be frustrating but could also be exciting.

So what about injecting a little excitement into marathon training with the occasional Oblique Training Run?

Monday, gym. Tuesday, easy run. Wednesday, go for a run dressed as superman.

Monday, gym. Tuesday, easy run. Wednesday, pack a picnic, run somewhere nice, get the bus home.

Monday, gym. Tuesday, easy run. Wednesday, get a head torch and run in the dark.

Run with a fast friend.

Run with a slow friend.

Make three people smile.

Run a route that draws a picture on the Strava map.

Run with a different soundtrack.

Run in silence.

I’m in training now; wish me luck. My fitness watch will be a vital part of my training practice, but it won’t be the only part. If you see an economist running up the river Thames dressed as Superman or carrying a picnic, that is because in running, as in life, much of what matters cannot be measured.

In their ability to track our running metrics, plot out complex progressions, and push us hard, fitness watches are a wrist-borne marvel. If I make it to the start line of the London marathon in April, I will have my watch on my wrist, pacing every step.

But like Pheidippides, I’ll also hope to have joy in my blood.

I’m running the London marathon run is in aid of the Teenage Cancer Trust. tinyurl.com/HarfordMarathon

First published in FT Magazine on 17 January 2026

When I was a very depressed British teenager, I had an unhealthy fascination with America. I found a way to love its contradictions, to explain away the obvious sins not by excusing them directly but by focusing on America’s enormous size, its capacity to hold infinite different types of people, and its proliferation of true weirdos. From my cramped and cold British bedroom, I browsed the website Roadside America and dreamed about driving across the country, before I could drive at all, to see things like the World’s Largest Chair, conveniently forgetting that most of what I saw along the way would be one-intersection towns with only chain restaurants and dialysis centers. To buy into that stuff is to value something that is odd and entirely itself above something that is good or otherwise defensible. Sure, this Museum of Long CVS Receipts sucks, but at least it sucks on its own terms; it’s not trying to be anything else, and it’s something that only this one guy who really loves receipts could create. You need this muscle, even if it’s buried deep down under crusted layers of realization about how the country actually sucks, to enjoy a visit to a place like Criss Angel’s Breakfast Lunch and Pizza in Overton, Nevada. 

Cablp, which is how the name is stylized (pronounced ca-blip), does indeed belong to magician Criss Angel, the Mindfreak himself. He founded the restaurant in July 2021, buying a local place called Sugar’s Home Plate and renovating it in a style befitting a freak of the mind. He told Nevada Public Radio in 2024 that he originally intended the restaurant to be just “one component to an escape camp for children with childhood cancer and other life-threatening diseases,” a cause that lies close to his heart, as his son Johnny Christopher has battled childhood leukemia (now in remission, thankfully). The camp part seems not to have made much progress; Angel said in the same interview that he was still “waiting years and years later for the county and Bureau of Land Management.” Perhaps it was a bad idea to open the restaurant before the escape camp could be built, but that’s not my business.

Cablp’s existence raises a lot of questions: Why is it in Overton and not at, for example, Planet Hollywood on the Las Vegas strip where Angel freaks minds every night? (Actually, that one is easy: Angel “fell in love with” Moapa Valley while taking his kids dirtbiking there.) Why does it serve breakfast, lunch, AND pizza, and why is it named for all three? Why would a magician need a restaurant? 

As the associate vice provost for the Office of Asynchronous Online Courses for Student-Centered High-Impact Learning (OAOCSCHIL, an office we created in the last few years after realizing how lucrative these things are), I want to address a growing concern on campus: the rumor that asynchronous online classes are “basically a scam.”

I understand the confusion. Outsiders are quick to pass judgment on these courses stocked with hastily recorded video lectures from 2020, auto-graded multiple-choice quizzes, and reflection message boards that are now 87 percent bots talking to other bots. Because there are no scheduled meetings with professors or classmates, and grading consists of counting whether students clicked the correct buttons, the fact that we charge tuition for the privilege of participating in these experiences could be mistaken for a scam: one in which no learning and very little effort are exchanged for grades and credits.

But, I assure you, this is not a scam. This is innovation.

Let me walk you through our new pedagogical model, which we in the OAOCSCHIL call Vibe-Teaching. You may have heard of “vibe-coding,” the revolutionary new software methodology in which programmers no longer understand code, write code, or even read code. They simply tell a large language model (LLM) what they want, run whatever it produces, and then tweak the prompt until the contraption is complete. Coding becomes cycles of evaluating outputs driven by persistent hopefulness.

Vibe-Teaching brings this cutting-edge, iterative feedback loop to higher education. Rather than building courses through faculty expertise or disciplinary knowledge, faculty gather complaints from alums now trying to get real jobs, feed those complaints into AI, and allow the system to revise the course accordingly. This continuous-improvement cycle transforms real-world disappointment into automated course updates, freeing faculty time for research (about AI), service (related to AI), and existential despair (you can guess the topic).

This instructional design reflects our commitment to inclusive pedagogy: All learning pathways are valid, whether students engage as manual human learners or outsource their consciousness to a chatbot. We support all modalities, confident that each demonstrates a different facet of multiple intelligences—or whatever we’re calling it this year.

In Vibe-Teaching, faculty are no longer required to read the AI-generated slop that students themselves have not paused to read. We only uphold one high-touch requirement: Vibe-Teaching faculty must log in every two weeks to respond to the pop-up message, “Are you still teaching?”

Some have asked why we don’t simply focus on helping students learn things. We appreciate the sentiment. Unfortunately, AI has made it impossible to measure actual learning. Every assignment is now an unverifiable collaboration between a stressed undergraduate and a VC-backed robo-parrot. Detecting “authentic” student thinking is technically possible, but prohibitively expensive. Think about it: We would need to pay real human faculty to interact with real human students. We do not have the budget for that.

So we have stopped trying to change student thinking. Instead, we focus on the continuous improvement of vibes. In lieu of learning outcomes, we now ask whether students have a warm sense of what learning might feel like and whether they can recall, with confidence, that they took “chemistry.” If so, we mark that as “exceeds expectations.”

And because we are a modern, data-driven institution, we have checked our dashboards to confirm the effectiveness of this approach. GPAs are rising, fail rates are down, and student satisfaction with online learning is trending in the right direction! Our website now proudly proclaims our AI-enhanced commitment to student success. The naysayers may fret about a post-literate world, but they have clearly not looked at the data. Numbers don’t lie.

From an institutional perspective, the benefits are substantial. Vibe-Teaching allows us to maximize enrollment and graduation rates without expanding facilities, faculty positions, or effort. It satisfies student demand for maximum flexibility, minimal cognitive effort, and zero human interaction, while meeting accreditation requirements (in vibes, if not in letter).

There is, of course, some risk of corroding the very foundations of our university’s mission. But institutional survival requires adaptation. Our graduates must become “AI-resilient and future-ready members of the workforce”… whatever that means.

The truth is, everyone wants this. Why they want it is beside the point. In light of these market demands, we humbly ask everyone to stop referring to asynchronous online courses as a “scam.” That word implies deception. In Vibe-Teaching, we are fully transparent:

We provide the illusion of education.
Students provide the illusion of engagement.
Together, we uphold the illusion of academic integrity.

The more informed we are, the more successful we’ll be in our decision-making endeavors. That’s only true up to a point: it’s only true if the information we’ve acquired is accurate and truthful. Making good decisions doesn’t merely rely on how much information we take in, it also depends on the quality of that information. If what we’ve instead ingested and accepted is misinformation or disinformation — incorrect information that doesn’t align with factual reality — then we not only become susceptible to grift and fraud ourselves, but we risk having our minds captured by charismatic charlatans. When that occurs, we can lose everything: money, trust, relationships, and even our mental independence.

This isn’t a problem that’s new here in 2026; this is a problem as old as humanity itself. When someone is compelling to us, and their arguments are convincing to us, we tend to go along with them, lauding both the idea and the one who puts it forth. We’re even more vulnerable if the idea is something that appeals to us emotionally, playing on our fears, hopes, preconceptions, preferences, or ideologies. However, no argument, no matter how well-crafted, can ever turn fiction into fact. It’s with this in mind that Carl Sagan, precisely 30 years ago, put forth what is now known as his “baloney detection kit” in his book, The Demon Haunted World, Science As A Candle in The Dark.

Here are nine timeless lessons we can all take to heart, and apply in our daily lives, when it comes to separating fact from fiction.

The galaxy JADES-GS-z14-0, imaged with JWST (background) and ALMA (inset), was found to contain telltale signatures of oxygen in its spectra, which were acquired by two independent teams observing this galaxy with ALMA. Its confirmed presence marks the earliest detection of oxygen in the Universe to date.

1.) Demand independent confirmation of whatever statements are asserted as facts.

In any matter that we consider, we always begin with the common ground of a starting point: with the facts and assumptions that underlie whatever topic we’re investigating. The key to making sure that we’re all on the same page is by stating what those facts and assumptions are up front, and by ensuring that everyone agrees on the truth of the facts being stated. This is only possible if:

• the facts are well-supported and/or well-established,
• the information underlying those facts has been obtained after a comprehensive and scrupulous analysis,
• and that those facts have been independently confirmed, ideally by people or teams who also aren’t stakeholders in the outcomes of those confirmation attempts.

It often turns out, upon closer examination or upon attempted replication, that what was once treated as a “fact” winds up being a much more disputed proposition. A line isn’t always the shortest distance between two points (that’s true only in flat space), black holes don’t evaporate because of particle-antiparticle pairs popping in-and-out of existence, and the far side of the Moon, invisible to all denizens of Earth until the development of spaceflight, doesn’t look similar to the Earth-facing side at all. Facts need to be robustly and responsibly established before they’re used to inform our decision-making process. All too often, especially when we’re eager to reach our preferred conclusion, we accept dubious assertions that are presented as facts without questioning whether this “fact” is actually representative of reality. We must tread cautiously, or we risk fooling ourselves.

Niels Bohr and Albert Einstein, discussing a great many topics in the home of Paul Ehrenfest in 1925. The Bohr-Einstein debates were one of the most influential occurrences during the development of quantum mechanics. Today, Bohr is best known for his quantum contributions, but Einstein is better-known for his contributions to relativity and mass-energy equivalence. Both were known for thinking long and hard about the most difficult puzzles the Universe had to offer.

2.) Encourage substantive debate from all points of view by those with substantial, relevant expertise.

This is an extremely important point, but one that we again must be very careful of. There is no shortage of debate happening in our modern world, including about issues that ignite our passions. That’s not necessarily a good thing, however. What we want is:

• substantive debate,
• where the underlying facts are accepted by everyone involved,
• where the proponents of different points of view are all knowledgeable experts,
• and where no one is lying, making up facts, engaging in the spreading of misinformation, or attempting to convince an onlooker of an alternative reality.

If Einstein and Bohr disagree over how to interpret our quantum reality, you can have a substantive debate over what it means, because everyone accepts the same facts, everyone involved is a knowledgeable expert, and everyone embraces our shared, measurable reality. However, when we have a widespread expert consensus about an issue, like the safety and utility of water fluoridation, the safety and efficacy of the (2024-era and earlier) childhood vaccination schedule, or the natural origins of SARS-CoV-2, debate only serves to sow doubt about well-established facts.

But we don’t want to undermine the best approximation of reality that human civilization can muster; we want to use all that we know and add in our capacity to reason and think critically to make informed decisions about how to have healthy, successful lives where we work together for the common good of all. That includes knowing when to listen to the signal and when to tune out the noise.

Italian astronomer Paolo Maffei’s promising work on infrared astronomy culminated in the discovery of galaxies — like Maffei 1 and 2, shown here — in the plane of the Milky Way itself. Maffei 1, the giant elliptical galaxy at the lower left, is the closest giant elliptical to the Milky Way, yet went undiscovered until 1967. For more than 40 years after the Great Debate, no spirals in the plane of the Milky Way were known, due to light-blocking dust that’s very effective at visible wavelengths.

3.) Don’t accept an argument from an authority because that person is an authority. Instead, judge arguments based on the merits of the underlying facts, and how experts scrupulously interpret those facts.

As Carl Sagan noted, even the most vaunted authority you can think of has made many mistakes in the past, and will do so again in the future. But in science, the only authority is the accepted suite of scientific facts and the well-established foundation of everything we’ve learned by applying those facts to our physical reality. There is no one authority figure we can go to and find out whether something is true or not based on what they say; we have to look at the merits of what is being argued and how well the facts support that argument.

Then we have to examine it and scrutinize it across a broad set of criteria.

• Does this argument fit the full suite of facts, or are there inconvenient findings that undermine the argument?
• Is this argument the only game in town, or are there alternative hypotheses that explain at least a large fraction of the agreed-upon facts just as well or better?
• Do the overwhelming majority of experts, independently, all draw and/or accept the same conclusions, and are their reasons for accepting those conclusions well-supported by the data?

It’s vital to remember that in science, all truths about reality are only provisional, representing the state of knowledge at the time. As we learn more, as we uncover new evidence, and as we enhance the full suite of data that we currently possess, a new, superior truth may yet emerge. It’s happened many times in the past, and will inevitably happen again.

When a grape is cut nearly perfectly in half, but a thin bridge of grape skin is left connecting them, a trip into the microwave will cause sparks to fly, creating a plasma along the bridge. Plasmas are created whenever electrons are kicked off of the atoms and molecules they were previously bound to, and at high enough energies and temperatures, all solids, liquids, and gases will become plasmas.

4.) Spin as many hypotheses as you can that are consistent with the data. Every possible explanation that isn’t ruled out or contradicted by the already-existing data should be considered, and each hypothesis should be tested and examined as rigorously as possible.

That’s how we do it: how we arrive at our best approximation of a scientific truth. We don’t choose our preferred idea and then look for evidence to support and defend it; although this is a common tactic used when we attempt to convince others to share our point-of-view, it has no place in the scientific enterprise. Instead, we attempt to be as neutral as possible, subjecting all hypotheses to the same strict scrutiny, attempting to falsify or poke holes in any idea by testing it as rigorously as possible.

In science, the key question that we always ask ourselves, when it comes to explaining any physical phenomenon, is “how?”

• How did this happen?
• How come this outcome or set of outcomes occurred, as opposed to any other possibility?
• How did a physical process, step-by-step, lead to the observations and measurements that we made?

It’s by considering all plausible answers to these questions, no matter how absurd they may seem, that we steadily improve our picture of reality and how it works. Many ideas that were rejected in the past receive new life upon a surprising new observation; many ideas that are accepted today will be overthrown when a key experimental result demonstrates its insufficiency. What passes for a “scientific truth” today may later be demoted to a crude and limited approximation that only applies under special circumstances, just as Newton’s laws are approximations to Einstein’s. That is not a failure of science; that is an essential part of the process.

Here, galaxy cluster MACS J0416.1-2403 isn’t in the process of collision, but rather is a non-interacting, asymmetrical cluster. It also emits a soft glow of intracluster light, produced by stars that are not part of any individual galaxy, helping reveal normal matter’s locations and distribution. Gravitational lensing effects are co-located with the matter, showing that “non-local” options for modified gravity do not apply to objects like this. Clusters of galaxies contain all sorts of small-scale structures within them, from black holes to planets to star-forming gas and more.

5.) Whatever your favorite, most preferred hypothesis is — especially if it’s your original idea — be its harshest critic. By attempting to knock it down or poke holes in it as hard as you can, you’ll determine how well it stands up under the steeliest of scrutiny. (And if you don’t, others will.)

This is one of the hardest aspects for non-scientists (and many low-quality scientists) to engage in: working hard to undermine your own work. “Why would anyone do that,” you might wonder. And the answer is simple: because the more invested you are in an idea being true, the stronger your instinct is to:

• overlook its flaws and faults, including all the ways it fails to explain reality,
• while overemphasizing and pointing to its strong points, especially in the ways it does align with reality.

If we ever hope to get at the truth and avoid succumbing to our prejudices — or, in this example, avoiding falling prey to baloney — we have to be skeptical of every idea, including and especially our own preferred idea, and subject it to the blindingly harsh light of reality.

Particularly in the era of LLM chatbots, which will flatter us and every one of our thoughts in conversation, self-inflicting this type of harsh criticism upon ourselves and our cherished ideas may seem especially unnerving. From a scientific, truth-seeking perspective, however, it’s an absolute mind-killer. If you can’t fathom abandoning your most preferred, cherished, deeply-held beliefs about the world because the evidence might contradict it, you’ve already fallen victim to the most insidious kind of baloney: the baloney that arises when we attempt to convince ourselves that we couldn’t possibly be wrong or mistaken. As Richard Feynman warned more than two decades before Carl Sagan’s book:

“The first principle is that you must not fool yourself — and you are the easiest person to fool. So you have to be very careful about that. After you’ve not fooled yourself, it’s easy not to fool other scientists. You just have to be honest in a conventional way after that.”

This diagram shows the energy budget of Earth, with incoming and outgoing radiation (values are shown in W/m^2). Satellite instruments (CERES) measure the reflected solar, and emitted infrared radiation fluxes. The energy balance determines Earth’s climate and temperature. When the Sun is directly overhead, atmospheric absorption is minimal, allowing for the best surface measurements of incident solar radiation on Earth.

6.) Don’t settle for a qualitative analysis of the issue. Be quantitative: ask and answer the key question of “by how much?”

This is something that a lot of non-scientists often overlook, particularly when it comes to scientific issues. If there are multiple possible explanations for something, and multiple contributing factors, how do you proceed? If you want to arrive at your preferred conclusion, you’ll talk in flowery terms about how massive or large an effect is, but you’ll avoid a comprehensive quantitative analysis. For example, the Earth has warmed over the past 250 years, and continues to warm even today. If you wanted to sow doubt about the cause of that warming, or to support an alternative-to-the-mainstream conclusion, you might point to a long list of contributing factors:

• the fact that we’re in the process of exiting an Ice Age,
• the fact that the Sun is variable and provides most of Earth’s energy,
• the fact that clouds trap heat, as do the natural gases in our atmosphere,
• and the fact that volcanoes not only cause cloud seeding, but contribute to heat-trapping through the greenhouse effect.

However, if you have sufficient expertise in the relevant areas (climate science and atmospheric science, for instance) and are approaching the problem scrupulously, you’ll ask the key question of how much each effect contributes. That also includes quantifying from the effects you might hope to downplay, such as the effect of human-created greenhouse gases due to the emission of fossil fuels and/or agricultural practices. It’s only by predicting both what happens and the amount that it’s going to happen by that we reach a physical understanding of what’s actually going on. Over a full century before Sagan’s writings, it was Lord Kelvin who said,

“…when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind: it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.”

This map shows a short period of wind data across the continental United States. While many once thought of wind as a phenomenon that required a source and was its own fundamental element, others held that wind was just a manifestation of air in motion, and that even air itself took up space and was capable of exerting forces. That latter viewpoint was a minority one, until the pre-Socratic philosopher/scientist Empedocles demonstrated the answer by showing that stationary air, in the absence of wind, could still exert a force.

7.) If there’s a chain of argument being put forth, then every link in the chain, from the premise to the final conclusion, must be sound.

They say that a chain is only as strong as its weakest link, and that’s just as true in the chain of logical reasoning as it is in the chains tethering a battleship to its anchors. A single weak link, including:

• assuming a single untrue assumption,
• relying on a discredited or fraudulent study,
• a logical error in reasoning,
• presenting an unsubstantiated assertion as an established fact,
• or ignoring an overlooked or omitted fact that undermines one of the key points,

can lead to an invalid conclusion being drawn.

This is why we must be careful not to misuse our ability to think critically or reason logically; if we misapply our toolkit — whether because of our own cluelessness (where we fool ourselves) or due to deliberate manipulation (where we purposely fool others) — we will wind up hiding, rather than highlighting, the points of evidence that contradict our narrative. If your goal is to get at the truth, or at least our closest approximation of it at the present time, the way to do that is to be scrupulous and forthright about the strengths and weaknesses of every link in your chain of argument. If one of today’s assumptions (or chain links) turns out to later be contradicted or overthrown, that is no failure on anyone’s part. That is how our understanding of the world improves and advances: one new fact and one additional piece of information at a time.

One of the great puzzles of the 1500s was how planets moved in an apparently retrograde fashion. This could either be explained through Ptolemy’s geocentric model (left), or Copernicus’ heliocentric one (right). However, getting the details right to arbitrary precision was something neither one could do. It would not be until Kepler’s notion of heliocentric, elliptical orbits, and the subsequent mechanism of gravitation proposed by Newton, that heliocentrism would triumph by scientific standards.

8.) The convenient rule of Occam’s Razor: to choose the simplest explanation among multiple hypotheses that explain the data equally well.

Also known as the principle of parsimony, Occam’s Razor is often paraphrased as, “all other things being equal, the simplest explanation is usually the best.” However, this too can be misapplied (and often is) in many ways, and we have to be aware of what those misapplications are in order to guard against them. They include:

• when multiple hypotheses have different levels of predictive, explanatory power (in which case, one of them will usually have the most such power),
• when multiple hypotheses that do explain one class of data equally well have non-equivalent instances that conflict with reality in some other fashion,
• or where one explanation is hailed as “simpler” despite actually requiring additional unproven assumptions as compared with another.

If multiple hypotheses do not explain the data equally well, then the one that explains the data more accurately and comprehensively is superior. If multiple hypotheses work to explain the data equally well but one conflicts with reality in some other realm (and the other doesn’t), the one that’s valid across the widest range of applicability is superior. And if two rival explanations each declare that they’re the simplest one, the way to tell is by looking at the number of additional assumptions that each one needs to invoke to be true; the one with fewer additional assumptions is simpler. (For example, “dark energy exists but evolves over time” is more complex than “dark energy exists and is a constant,” because it requires a greater number of parameters to model dark energy in that fashion.)

When all else is equal, the simplest explanation is usually best, but only if all else is equal, and only if we are careful with how we apply the notion of “simple” to the problem in question.

The truth about reality is written on the face of the Universe itself, and can be discerned via the process of scientific inquiry. At least, that’s the assumption we make, and it’s been quite fruitful so far. But this, like all other scientific ideas, is always subject to being overturned with new observations and experiments, and replaced by a more successful approximation of reality.

9.) Ask whether the hypothesis, at least in principle, can be falsified. Non-falsifiable and untestable hypotheses cannot be checked out, and hence those ideas are incapable of disproof.

This is not a benefit; this is the hallmark of all ideas that aren’t worth very much. There are plenty of ideas that one can concoct that cannot be disproven, but that also don’t predict anything that can be tested. When I was a child, I had one such idea: the idea that the Universe was created for me at the moment of my birth, with no one else actually existing. All historical records, photographs, written texts, everyone else’s memories and experiences, etc., were created along with the Universe at the moment of my birth, so that no one would be aware of this. Certainly, this idea cannot be disproven — not by me and not by anyone else with a similar idea about themselves — but it lacks the power to explain anything as well.

If it cannot be falsified by any sort of evidence, and it lacks explanatory power to quantitatively describe reality, then it isn’t worth very much to others. As Thomas Henry Huxley put it long ago,

“The foundation of all morality is to have done, once and for all, with lying; to give up pretending to believe that for which there is no evidence, and repeating unintelligible propositions about things beyond the possibilities of knowledge.”

Although we do not yet live in a world exclusively governed by rationality, skepticism, and critical thought as envisioned by Sagan, Huxley, and many others, these nine lessons remain vital tools in the eternal war against misinformation, grift, and fraud. The entire scientific enterprise remains the most meaningful method for obtaining factual knowledge about reality, and it’s by following these lessons that we’ve achieved all that we have as a civilization. To go further still, these lessons must never be forgotten.

This article Carl Sagan’s 9 timeless lessons for detecting baloney is featured on Big Think.

LADAKH, India — High on the wind-swept plains of the Changthang plateau, in Ladakh, along the northern tip of India, the world seems untouched by time.

Changthang, Tibetan for “Northern Plateau,” stretches across Ladakh into western Tibet, a seemingly barren expanse of stone, salt and sky. It is a high-altitude desert where life has adapted over centuries to harsh winds, scarce water and extreme cold.

Yaks lumber across the dusty mountain earth, their breath rising in clouds. Behind them, Thinlay Nurboo, a yak herder, holds a handmade rope with a small stone tied to its end in his hand. Nurboo throws the stone forward to startle approaching wild animals and keep his yaks safe.

For generations, the people of Ladakh have shaped their lives and cultural practices around the mountains, farming barley on limited arable land and managing increasingly scarce glacial water that relies on once-regular snowfalls.

“Today, those rhythms are broken,” Nurboo says.

Ladakh, often romanticized for its stark beauty and Buddhist monasteries perched on cliffs, is now a frontline in the global climate crisis. In just the last few decades, villagers speak of winters that arrive late and leave early. Glaciers that fed entire valleys have shrunk into bare rock. Streams that once ran through the summer months dry up by mid-June. In most places, the land is turning to dust.

Local Ladakhi communities, supported by engineers and environmentalists, are building artificial glaciers and reviving ancient water systems to sustain water for agriculture. But the future remains uncertain. A high-altitude desert that once depended on the stability of seasons is now caught in the chaos of a warming world.

Beyond environmental challenges, the march of modernity is changing how people view their own lives. Education, urban jobs, tourism and new technologies offer opportunities, but they also shift values, creating subtle pressures that make traditional practices seem outdated or less respected.

“In Tibet, under Chinese occupation, the erasure of Tibetan culture was violent,” Sonam Wangchuk, an engineer and environmentalist known for his work on Ladakh’s water systems, said. “But in Ladakh, it is different. Here, traditions like yak herding are vanishing quietly, without force.”

The traditional semi-nomadic way of life herders like Nurboo live — a delicate balance of reciprocity with land and animals — is quietly unravelling under the pull of modernity and the pressures of climate change and militarized geopolitics.

In Changthang, yak herders are increasingly viewed as backward, their dialects ridiculed, and this makes getting married difficult, explained Nurboo, who looks younger than his 35 years. The stigma is often a stronger force than economics. People abandon herding not because it cannot sustain them, but because they begin to feel inferior about their way of life.

“Once that happens, a culture can disappear without a single act of violence,” Nurboo tells us.

A Vanishing Way of Life

On the high-altitude plains of the Himalayas, wind gusts, and the air is sharp with cold, even though it is mid-June. Nurboo follows a moving herd of yaks a couple of miles from his nomadic farm. His boots are wet with yak dung from traversing the higher mountain peaks in search of grazing land.

Unlike other livestock, yaks require specialized care, high-altitude grazing and seasonal migrations across rugged terrain. While goats, sheep and cows are still herded at lower altitudes, yak herding is increasingly rare. Local elders believe Nurboo is one of the last practicing yak herders in the region, keeping the centuries-old tradition that has quietly structured life in the upper Himalayas. 

“Not everyone today wants to live this way,” he says, sitting inside a tent he and his father made. His home is a traditional rebo, crafted from hand-woven yak hair and wool by Changpa nomads. Durable and insulating, it serves as shelter during seasonal migrations. 

“In recent years, some families have added simple side sheds, semi-permanent stone or tin structures, or modern canvas tents for storage and daily chores,” Nurboo tells us, continuing to live in the traditional style. “They call it backward, and the people, especially the younger generations, [don’t] want to follow this tradition.”

These days, Nurboo cares for 90 of his own yaks and around 100 yaks belonging to villagers who have left herding.

The government has worked to support herding communities by resettling them in more strategically located border villages under the Vibrant Village Programme. Meanwhile, promises of salaried work have drawn people to Ladakh’s capital, Leh, roughly 130 miles away, or to the town of Srinagar, about 260 miles away.