“It is an irony of history that Galton started out in search of causation and ended up discovering correlation, a relationship that is oblivious of causation,” writes Judea Pearl in his book The Book of Why. Pearl examines the history of the study of causation in his book suggesting that Galton abandoned his original quest to define causation. Galton, along with Karl Pearson is a titanic figure in the study of statistics. The pair are in many ways responsible for the path of modern statistics, but as Pearl describes it, that was not the original intent, at least for Galton.
Pearl describes Galton as trying to work toward universal theories and approaches to causation. Correlation, the end product of Galton’s research is helpful and a vital part of how we understand the world today, but it is not causation. Correlation does not tell us if one thing causes another, only that a relationship exists. It doesn’t tell us which way the arrow of causation moves and whether other factors are important in causation. It tells us that as one thing changes, another changes with it, or that as other variables adjust, outcomes in the specific thing we want to see also adjust. But from correlation and statistical studies, we don’t truly know why the world works the way it does. I think that Pearl would argue that in its best form, statistics helps us narrow down causal possibilities and pathways, but it never tells us with any certainty that a relationship exists because of specific causal factors.
The direction of Galton’s research is emblematic of science and of our lives in general. Galton set out in search of one thing, and gave rise to an entirely different field of study. For his work he clearly became successful, influential, and well regarded, but today (as Pearl argues) we are living with the consequences of his work. We haven’t been able to move forward from the paradigm he created. A paradigm he didn’t really set out to establish.
Quite often in our lives we follow paths that we don’t fully understand, ending up in places we didn’t quite expect. We can make the most out of where our journeys take us and live full lives, even if we didn’t expect to be where we are living. We can’t fully control where the path takes us, and if we chose to stop, there is no reason the path has to stop as well. What we set out to do can become more than us, and can carry far beyond our imaginations, and the world will have to live with those consequences, even if we walk away or pass away.
They key point in this post is to remember that the world is complex. Remember that what you see is only a partial slice, that your causal explanations of the world may be inaccurate, and that the correlations you see are not complete explanations of reality. The path you walk shapes the future of the world, for you and for others, so you have a responsibility to make the best decisions you can, and to live well with the destination you reach, even if it isn’t the destination you thought you were walking toward. Your journey will end at some point, but the path you start could keep going far beyond your end-point, so consider whether you are leaving a path that others can continue to follow, or if you are forging a trail that will cause problems down the road. The lesson is to be considerate and make the most out of the winding and unpredictable path ahead of you as you set out on your quest.