Non Causa Pro Causa
Translation: "Non-cause for cause", Latin
Alias: False Cause
Type: Informal Fallacy
This is the most general fallacy of reasoning to conclusions about causality. Some authors describe it as inferring that something is the cause of something else when it isn't, an interpretation encouraged by the fallacy's names. However, inferring a false causal relation is often just a mistake, and it can be the result of reasoning which is as cogent as can be, since all reasoning to causal conclusions is ultimately inductive. Instead, to be fallacious, a causal argument must violate the canons of good reasoning about causation in some common or deceptive way. Thus, to understand causal fallacies, we must understand how causal reasoning works, and the ways in which it can go awry.
Causal conclusions can take one of two forms:
- Event-Level: Sometimes we wish to know the cause of a particular event, for instance, a physician conducting a medical examination is inquiring into the cause of a particular patient's illness. Specific events are caused by other specific events, so the conclusion we aim at in this kind of causal reasoning has the form:
Event C caused event E.
Mistakes about event-level causation are the result of confusing coincidence with causation. Event C may occur at the same time as event E, or just before it, without being the cause of E. It may simply be happenstance that these two events occurred at about the same time. In order to find the correct event that caused an effect, we must reason from a causal law, which introduces the next level of causal reasoning:
- Type-Level: A causal law has the form:
Events of type C cause events of type E.
Here, we are not talking about a causal relation holding between two particular events, but the general causal relation holding between instances of two types of event. For example, when we say that smoking cigarettes causes lung cancer, we are not talking about an individual act of smoking causing a particular case of lung cancer. Rather, we mean that smoking is a type of event which causes another type of event, namely, cancer.
Mistakes about type-level causation are the result of confusing correlation with causation. Two types of event may occur simultaneously, or one type always following the other type, without there being a causal relation between them. One common source of non-causal correlations between two event-types is when both are effects of a third type of event. For examples of causal fallacies, see the Subfallacies of Non Causa Pro Causa:
David Hackett Fischer, Historians' Fallacies: Toward a Logic of Historical Thought (Harper & Row, 1970), Chapter VI: "Fallacies of Causation".