Title: Causality is complex: An illustration
Course: UGQuants (SSPS) > Section: Causality

Causality is complex: An illustration

We are usually interested not just in the simple empirical existence of some pattern or correlation, but also in some kind of theory that makes sense of, explains, or identifies some cause behind it. For example, we are less interested in the empirical fact that objects always fall towards earth than in elaborating a theory of gravity that might explain why this should be so. If we have two variables that appear to be correlated, we can ask the question of whether we can identify a causal relationship between them.

For example, if I drink a bottle of wine and become drunk, I might conclude that drinking the wine made me, or caused me to become drunk. We might well establish a strong correlation between the event of drinking a bottle of wine and the event of being drunk. I could not conclude that being drunk caused me to drink the bottle of wine, as (at least to begin with) one event preceded the other. I might eventually conclude that the relationship was one of cause and effect. Suppose I like to accompany my glass(es) of wine with a cigarette, and later I am diagnosed as suffering heart disease. Can I blame the cigarettes? If I blame the cigarettes, why not also the wine? And if I blame the wine, is it because it also caused my heart condition, or only because it encouraged my desire to smoke? And if I blame any of these things, is the real culprit not me? Did anything 'cause' me to smoke or drink? Did I not choose to drink and smoke of my own free will?  Had cigarettes either not been invented or available for sale, I could not have smoked. Should I then sue the heirs of Sir Walter Raleigh, the tobacco companies or the government for 'causing' my condition? Or maybe I would have got heart disease anyway. Maybe the cause was 'genetic'. I should have chosen my parents more carefully, not my drinking or smoking habits. This simple example gives a flavour of the complexity of introducing a causal element to our analysis. However, if we wish to say almost anything interesting or relevant to the real world, we have to address causal patterns in some way.