DIRECTIONS: Four things somebody proved, and when anybody acted. Work out each gap.
What was shown, and by whom
Proved
Acted on
The gap
1.Lemon juice stops scurvy James Lind ran the trial — six pairs of sick sailors, six treatments, and only the two on citrus recovered
1747
1795
2.Washing your hands between patients Semmelweis moved doctors onto a chlorine wash and the death rate on his ward fell to a fraction
1847
1885
3.A clock at sea, for knowing where you are Harrison’s clock crossed the Atlantic and kept time
1761
1825
4.The three-point seat belt Volvo fitted it, and gave the patent away so anybody could use it
1959
1984
The average of your four numbers is about 44 years. Nobody in any of these stories was waiting for more evidence. The evidence was already there, published, and in two of the four cases dramatic.
Scurvy killed more British sailors in the eighteenth century than every battle put together. The gap on row 1 is not an abstraction — it is roughly two generations of men who died of something that had a known cure sitting in a published book.
The dates are round: "it became normal" is a process, not a day. A 48-year gap survives being five years off.
They Knew — Before You Decide Why
Why it took so long to change · Page 2 of 2
There is an obvious answer and you should write it down before you are talked out of it. Most people say: they were stupid, or they did not care.
Hold that thought until sheet 20. If it turns out to be wrong, it matters WHY it is wrong — because it is the most popular explanation for every delay of this kind, including the ones happening now.
Write down, honestly, what you think the reason was before reading anything else. You will come back to this.
Row 1 and row 2 have something in common that rows 3 and 4 do not: in both, the person who found the answer could not say why it worked. Say why that would make a true finding easy to ignore.
Pick the gap you find hardest to believe, and say what you would want to know before judging anybody in it.