Two years ago, I started learning Japanese on Duolingo. At first, the daily accrual of vocabulary was fun. Every lesson earned me experience points – a little reward that measured and reinforced my progress.

But something odd happened. Over time, my focus shifted. As I climbed the weekly leaderboards, I found myself favouring lessons that offered the most points for the least effort. Things came to a head when I passed an entire holiday glued to my phone, repeating the same 30-second Kanji lesson over and over like a pigeon pecking a lever, ignoring my family and learning nothing.

Philosopher C Thi Nguyen’s new book tackles precisely this kind of perverse behaviour. He argues that mistaking points for the point is a pervasive error that leads us to build our lives and societies around things we don’t want. “Value capture”, as Nguyen calls it, happens when the lines between what you care about and how you measure your progress, begin to blur. You internalise the metric – in some sense it supplants your original goal – until it has “redefined your core sense of what’s important”.

He gives the example of American law school league tables, introduced to offer an ostensibly objective yardstick for candidates who had previously relied on promotional material and insider gossip. The new, supposedly hard, data focused on a few, narrow metrics.

Where previously law schools would distinguish themselves with mission statements outlining their unique philosophy and emphasis, league tables collapsed these nuanced, hard-to-quantify values into a single number – and forced schools to either chase that number, or lose out on funding and students. The result, Nguyen tells us, is that “huge shares of university resources have been diverted away from genuine pedagogical activity and toward efforts designed only to game the rankings”.

Part of that ranking is calculated by how many applicants a school rejects each year. The logic goes: the higher the rejection rate, the more elite and desirable the school. This, Nguyen says, encourages many law schools to spend money soliciting applications from students with almost no chance of getting in, “simply so they’ll have more people to reject”.

Nguyen is lucid, entertaining and precise, illustrating ideas with a mix of personal stories and real-world examples. He has a particular knack for conveying the specific, intrinsic pleasures of his many enthusiasms, from “the explosive hip twists” and “sweet joy” of rock climbing, to the meditative alchemy of fly-fishing, where he becomes “a nexus point in this gorgeously overwhelming flow of information”. The point of fly-fishing isn’t to catch a fish – it’s how you feel while trying to catch a fish.

I was always going to be charmed by a book that can reference Reiner Knizia (“the Mozart of German game design”) one moment and Mario Odyssey speedruns the next. But this is no niche treatise. Value capture leads us, Nguyen argues, to waste our lives. We optimise for salary or YouTube views or our position on a leaderboard (he admits having made himself miserable by obsessing over philosophy department and journal rankings), and neglect the experiences that make life worth living.

And at the level of society, value capture makes us fixate on metrics such as GDP, employment figures and exam grades. Quantitative data promises to turn hugely complex cross-sections of our world into portable summaries. It’s a seductive bargain: “delicious clarity” in the form of a simple score, at the expense of context and nuance. “This is the thought that actually keeps me awake at night,” says Nguyen, the “grim truth about the heart of data”.

Our uncritical reverence for metrics allows for what Nguyen calls “objectivity laundering” – bureaucrats disguising their agency in decisions regarding our schools, hospitals and wellbeing, by evoking “the numbers” as impartial arbiters. Those in power choose which metrics to champion, then claim actions driven by those metrics somehow transcend ideology.

The Score is a compelling read, urgent but never alarmist. For Nguyen, wonder, absorption and play are central to human flourishing. Metrics are a kind of invasive species threatening to replace our weird, delicate joys with the dumbed-down epistemic fundamentalism of league tables and graphs. Despite – or perhaps because of – the gravity of these issues, I came away enriched and uplifted.