The Wisdom Audit, part 3 of 9. This series tests famous sayings against published research and ends each test with a verdict.
Three sayings tell you when to leave things alone and when to intervene. Curiosity killed the cat warns you not to investigate out of pure interest. If it ain’t broke, don’t fix it warns you not to touch what is working. Necessity is the mother of invention promises that invention arrives only when you have no other choice.
Together they sketch a complete philosophy of intervention: touch things only when forced. Let’s test it.
Curiosity killed the cat
Origin: The cat was never killed by curiosity. Ben Jonson wrote “care’ll kill a cat” in 1598, and Shakespeare used “care killed a cat” in Much Ado About Nothing a year later. Care meant worry, so the saying originally warned that anxiety is lethal. “Curiosity” doesn’t show up in print until 1868, and the rebuttal clause, “but satisfaction brought it back,” arrives around 1912. This proverb mutated twice in three centuries and reversed its meaning along the way.
What it actually claims: curiosity carries costs that outweigh its benefits.
The data runs hard the other way. In 2014, Gruber, Gelman, and Ranganath showed that when people are in a state of high curiosity, they remember not just the thing they were curious about but unrelated incidental information they encountered along the way, with brain imaging showing the reward system and the memory system lighting up together. Curiosity literally opens the memory aperture. In 2011, von Stumm, Hell, and Chamorro-Premuzic pooled the results of dozens of studies on academic performance and found intellectual curiosity’s effect comparable to conscientiousness, with curiosity plus effort together rivaling intelligence itself. They called it the hungry mind.
Show me the study where trait curiosity kills anything. It doesn’t exist. The original saying, the one about worry, has a far better evidentiary record.
Verdict: Fails. The cat died of care, and we reassigned the blame to the one trait the data says to feed.
The rewrite: Worry killed the cat. Curiosity ran the autopsy and learned something.
If it ain’t broke, don’t fix it
Origin: This is the youngest saying in the series. It circulated in the American South by the early 1960s and went national in May 1977, when Bert Lance, President Carter’s budget director, used it in Nation’s Business.
What it actually claims: intervening in working systems costs more than it returns.
The data splits cleanly along one variable. The case for the saying starts with status quo bias. Samuelson and Zeckhauser showed in 1988 that people disproportionately stick with defaults in everything from health plans to retirement allocations, but the same research shows we also overvalue the status quo irrationally, which cuts against treating “leave it alone” as wisdom rather than reflex. Medicine adds its own evidence for restraint: the overdiagnosis and overtreatment literature that produced the Choosing Wisely campaign documents real harm from fixing things that weren’t broken.
The case against the saying comes from engineering. The US Department of Energy’s operations and maintenance guide puts the savings of a functioning predictive maintenance program at 8 to 12 percent over preventive maintenance, and 30 to 40 percent over the run-to-failure strategy this proverb recommends. Machines that “ain’t broke” are frequently in the process of breaking, and detecting that early is dramatically cheaper than waiting.
So which is it? The deciding variable is the cost structure. When intervention itself carries risk and failure is cheap or self-announcing, leave it alone. When failure is expensive and detection is cheap, the proverb is a wealth transfer from your future self to your present one.
Verdict: Split. Bert Lance was right about government reorganization and wrong about turbines.
The rewrite: If it ain’t broke, check what breaking costs before you decide not to look.
Necessity is the mother of invention
Origin: Everyone says Plato. The famous English wording is actually Benjamin Jowett’s 1871 translation of a line in the Republic that reads, more literally, “our need will be the real creator.” The idea was already an English proverb by 1519, when William Horman’s Vulgaria included “Nede taught hym wytte,” and the Latin tag “mater artium necessitas” carried it through the schoolrooms.
What it actually claims: constraint produces more invention than abundance.
The data supports it, up to a sharp threshold. Mehta and Zhu showed across six experiments in 2016 that when resources feel scarce, people stop seeing objects only in their usual roles and come up with more inventive uses for what’s in front of them, while abundance makes us lazy about materials. At the level of firms, the Kauffman Foundation looked at the 2009 Fortune 500 and found that well over half, 57 percent of the firms founded since 1855, began in a recession or bear market.
Then comes the threshold. Mani, Mullainathan, Shafir, and Zhao showed in Science in 2013 that genuine financial scarcity consumes cognitive bandwidth, dragging performance down by the equivalent of about 13 IQ points, roughly a full night of lost sleep. The same sugarcane farmers scored measurably worse before harvest, when money was tight, than after. Mild constraint focuses invention. Deep scarcity taxes the exact cognition invention requires.
Verdict: Conditional. Necessity is the mother of invention until necessity is eating the mother.
The rewrite: Constraint sharpens and scarcity dulls. Know which one you’re in.
When to intervene: the actual decision rule
The three sayings collapse into a two-by-two.
| Failure is cheap | Failure is expensive | |
|---|---|---|
| Intervention is cheap | Investigate freely. This is where curiosity lives, and curiosity pays | Check early and often. This is predictive maintenance territory, with 30 to 40 percent savings |
| Intervention is expensive or risky | Leave it alone. This is overtreatment territory | This is the genuinely hard quadrant. Invest in better detection before deciding |
Notice what happened here: the newest saying in the series (1977, an American budget office) and one of the oldest ideas (Plato by way of a Victorian translator) both turned out to be quarter-truths sharing a decision rule neither of them states. The wisdom wasn’t wrong. It was unfinished.
Next in the series: Look Before You Leap. But Not for Long.
Sources: Gruber, Gelman & Ranganath 2014 (Neuron 84); von Stumm, Hell & Chamorro-Premuzic 2011 (Perspectives on Psychological Science 6); Samuelson & Zeckhauser 1988 (Journal of Risk and Uncertainty 1); US DOE FEMP O&M Best Practices Guide, Release 3.0; Mehta & Zhu 2016 (Journal of Consumer Research 42); Kauffman Foundation 2009, “The Economic Future Just Happened”; Mani, Mullainathan, Shafir & Zhao 2013 (Science 341); etymologies via the Oxford proverb literature and phrases.org.uk.
Laurie Stach 