Ideas from first-principles thinking

• Move 1 · Name the claim

  Count the dead by cause

  Florence Nightingale · 1858 · Public health

  Turn a vague claim into numbers that could prove it wrong.

  How Count the dead by cause came about

  What everyone assumed

  Deaths in the Crimean War were taken as the price of battle. One number covered them all.

  What they reasoned from

  She split one vague claim into countable ones. Deaths from wounds, from disease and from other causes, month by month.

  What came of it

  Her 1858 report drew the counts as wedges. Preventable disease killed far more soldiers than wounds did.

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  Source: Florence Nightingale, Notes on Matters Affecting the Health, Efficiency and Hospital Administration of the British Army (1858) (opens in a new tab)

• Move 2 · Find the assumption

  Two wards, one difference

  Ignaz Semmelweis · 1847 · Medicine

  When two groups differ, write down what you assumed was the same.

  How Two wards, one difference came about

  What everyone assumed

  Most doctors of the day blamed childbed fever on bad air.

  What they reasoned from

  He listed what the two wards were assumed to share and found one difference. Doctors came from the autopsy room. Midwives did not.

  What came of it

  In May 1847 he made staff wash their hands in chlorinated lime. Deaths in the doctors' ward fell to 1.27 percent in 1848.

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  Source: Ignaz Semmelweis, Die Aetiologie, der Begriff und die Prophylaxis des Kindbettfiebers (1861), English translation by K. Codell Carter (1983) (opens in a new tab)

• Move 3 · Ask why until it stops

  Where the chain of whys must stop

  Aristotle · c. 350 BCE · Philosophy

  Stop asking why only when you reach something you can observe, measure or prove.

  How Where the chain of whys must stop came about

  What everyone assumed

  Some argued that every proof needs a prior proof, so nothing is ever known.

  What they reasoned from

  Aristotle said the chain must stop. It stops at first principles, which are grasped directly rather than proved.

  What came of it

  His account of a science rests on this. Every demonstration starts from premises that need no further proof.

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  Source: Aristotle, Posterior Analytics, Book I, chapter 3 (c. 350 BCE), trans. G. R. G. Mure (opens in a new tab)

• Move 3 · Ask why until it stops

  Ask why the cell fights the message

  Katalin Karikó and Drew Weissman · 2005 · Biology

  When something fails, ask why until you reach the one difference you can change.

  How Ask why the cell fights the message came about

  What everyone assumed

  Synthetic messenger RNA set off inflammation in cells, so many judged it a dead end for medicine.

  What they reasoned from

  They asked why. The immune system recognised the RNA. Why not the cell's own transfer RNA? Its building blocks were chemically modified.

  What came of it

  Swapping in modified nucleosides quieted the response. The 2005 paper underlies the mRNA vaccines of 2020.

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  Source: Karikó, Buckstein, Ni and Weissman, Suppression of RNA Recognition by Toll-like Receptors, Immunity 23(2) (2005) (opens in a new tab)

• Move 4 · Rebuild from what is certain

  Measure the lift yourself

  Wilbur and Orville Wright · 1901 · Aeronautics

  When a borrowed number fails you, measure it yourself and build from your own.

  How Measure the lift yourself came about

  What everyone assumed

  Published lift tables were taken as reliable by everyone building gliders.

  What they reasoned from

  Their 1901 glider lifted far less than the tables predicted. So they built a wind tunnel and measured their own wing shapes.

  What came of it

  That autumn they tested many small wings. The data shaped the 1902 glider and the 1903 aircraft.

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  Source: Wilbur Wright, Some Aeronautical Experiments, address to the Western Society of Engineers (1901), on the glider's shortfall (opens in a new tab)

• Move 4 · Rebuild from what is certain

  Plot every sounding

  Marie Tharp · 1952 · Geology

  Build the picture from the raw numbers before you accept what everyone says is there.

  How Plot every sounding came about

  What everyone assumed

  Most geologists held that the seafloor was featureless and that continents do not move.

  What they reasoned from

  She plotted thousands of soundings by hand into profiles across the North Atlantic. Each showed a notch at the ridge crest, in line.

  What came of it

  Her colleague first called it an error. Earthquake centres then fell inside the notch. The 1959 map showed a rift valley along the ridge.

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  Source: Marie Tharp, Connect the Dots (1999) and Heezen, Tharp and Ewing, The Floors of the Oceans I (1959) (opens in a new tab)

• Move 5 · Test what breaks

  Light comes in, not out

  Ibn al-Haytham · c. 1011 to 1021 · Optics

  Find the one everyday observation your theory cannot survive.

  How Light comes in, not out came about

  What everyone assumed

  Many held, after Euclid and Ptolemy, that the eye sends out rays and sees by touching objects with them.

  What they reasoned from

  He asked what breaks that view. Looking at the sun hurts the eye, so something enters it. Light travels from object to eye.

  What came of it

  His Book of Optics built vision on light entering the eye, one ray from each point. Scholars in Europe read it for centuries.

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  Source: Ibn al-Haytham, Kitab al-Manazir (Book of Optics), c. 1011 to 1021, summarised by S. S. Amr, Annals of Saudi Medicine (2007) (opens in a new tab)

• Move 5 · Test what breaks

  A glass of ice water

  Richard Feynman · 1986 · Engineering

  Find the cheapest test you can run yourself before you ask for more data.

  How A glass of ice water came about

  What everyone assumed

  Earlier flights had survived, so the seals were judged safe enough.

  What they reasoned from

  The seal had to close in a fraction of a second. The agency's reply measured recovery over hours, so he made his own test.

  What came of it

  At a public hearing he showed that rubber in ice water lost its spring. He judged the cold a likely cause. The commission agreed.

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  Source: Richard Feynman, Mr. Feynman Goes to Washington, Engineering and Science 51(1) (1987) (opens in a new tab)