When do we act, how do we act, and how do we justify our decision in a realm of uncertainty and risks? I just read an essay about John Snow and the Cholera epidemic in London 1854. This was yet a time where bacteria were not yet discovered, where a manifold of theories circulated to explain disasters of this kind.
Snow’s observations, his assessment of the situation, his method of interpreting his observations / data made a cause-effect relation transparent that lead the way for an intervention policy stopping the epidemic. With his investigative approach Snow was able to submit all the necessary data that were convincing enough for policy-makers to act.
Source: www.personal.psu.edu
He gave them enough evidence that they believed in his theory of impure water being the culprit for the cholera epidemic. John Snow collected figures and put them in a temporal-spatial grid. He applied statistical and graphical reasoning. So he was able to interpret his observations and turn them into so-called scientific data. A method that appears so normal to us today, so normal that it may even obscure our minds. Think about it. As soon as things get normal we loose sensitivity and become numb. The ability to observe needs the ability to discriminate. If this is not the case it may lead to the impression that evidence is absent and this may lead to a wrong conclusion of an evidence of absence 😉 got it …?
To cut a long story short: “In London’s Broad Street”, John Snow suggested, “it is a water pump that pollutes the water that causes the cholera”. Poeple trusted his theory.
In 1886 the bacterium Vibrio cholerae confirmed Snow’s theory.
Looking back in time and knowing the whole story makes solving the problem look easy. It was not in those days it meant a revolution in thinking and applied method.
Why could he solve the problem? Most importantly! Snow had a good idea that guided him by gathering and assessing his empirical observations, his evidence. Whether it always has to be a linear cause-effect relation – we became so used to in our Western culture – may be doubted.
