1.9: Causation

Causation is about how one event brings about another event. The most important point to remember about causation is probably the advice that one should not confuse correlation with causation. Suppose events of type A are positively correlated with events of type B. One common mistake in causal reasoning is to jump to the conclusion that A is therefore the cause of B. This is bad reasoning because we have not ruled out other possible explanations, such as:

• The order of causation is reversed– Suppose people who like to play violent video games are more likely to engage in violent behaviour. Does it mean those games make people violent? Maybe. But it could also be the other way round. Perhaps people who are predisposed to violence are more likely to enjoy and play violent video games, but the games themselves do not make people more violent.
• The correlated events have a common cause– It is said that when ice-cream sale increases,so does the number of shark attacks on swimmers. Does eating ice-cream make sharks attack people? Of course not. There is a correlation only because when the weather is hot, more people go swimming and more people eat ice-cream. Hot weather is the underlying causal factor that links the two factors but there is no direct causal connection between them.
• The correlation is an accident– A correlation provides evidence for causation only if the correlation is robust and can be observed repeatedly. If you manage to lose weight after eating less carbohydrates for a few weeks, this might just be a coincidence. Perhaps it is just because you ended up eating less when you are more aware of your diet. We need more evidence to decide whether eating less carbohydrates is a good way to control one’s weight.

Some common mistakes in causal reasoning

• Genetic fallacy– Thinking that if some item X comes from a source with a certain property,then X must have the same property as well. But the conclusion does not follow, e.g.Eugenics was practised by the Nazis so it is obviously disgusting and unacceptable.
• Fallacy of the single cause– Wrongly presupposing that an event has a single cause when there are many causally relevant factors involved. This is a fallacy where causal interactions are being over-simplified. For example, when a student committed suicide, the public and the media might start looking for the cause, and blame the tragedy on either the parents,the school work, the society, etc. But there need not be a single cause that led to the suicide. Many factors might be at work.
• Confusing good causal consequences with reasons for belief– Thinking that a claim must be true because believing in it brings about some benefit. Examples: God exists because after I have become a believer I am now happier and a better person. I don’t think my girlfriend is cheating on me because otherwise it is the end of my world and I cannot accept that. These examples might seem unrealistic because people often do not state their reasons so explicitly, but we should not underestimate how emotions can bias our reasoning in more subtle ways.