It is every philosopher’s dream to one day divine the meaning of the universe, to reveal the grand scheme of things for all to see. David Hume endeavors towards a goal no less difficult in trying to unlock the connection between simple cause and effect relations. In his novel An Enquiry Concerning Human Understanding, he presents two views of causation. The first is focussed around the constant conjunction of an alleged cause and the resultant effect. The second is a counter-factual account of causation which Hume sees as equivalent to his theory of constant conjunction. But can these two views, once understood, be regarded as identical?
With constant conjunction, Hume explains that an event can be considered the cause of another event if and only if all events like the former are constantly conjoined with the latter type of event and if the latter succeeds the former temporally. More simply put, because the flicking of a light switch has been, in a viewer’s experience, constantly followed by (conjoined with) the lights coming on, when the light do come on right after a light switch is thrown, the viewer can assume the cause to be the throwing of the switch. Hume accepts that one cannot know the true cause, the most basic of causes, but he does assert that the cause, in a practical sense, can be probabilistically inferred. If the conjunction of two events is consistent enough, one can go so far as to even be certain (with little doubt) of the relation between them continuing.
Hume then presents a counter-factual account of causation as a simple rewording of his constant conjunction supposition. This account states that one event is the cause of another if and only if had the former not occurred, the latter would not have. This, to assess it in the former example, says that the switch is the cause of the lights going on for, had the switch not been thrown, the lights would not have gone on.
Though both ideas make logical sense and seem, individually, to be good ways of deriving the cause of some event, Hume goes too far in saying that the two concepts are the same. His constant conjunction account of causation requires that the observer of the relation has had the proper experiences, the proper conjunctions, to arrive at an accurate conclusion of causation. “Observer” is used here in a loose sense; it is any unit external to the events, be it a person or a society or a school of thought. His counter-factual account implies more of a necessary connection between the two, where a constant conjunction is irrelevant. If a totally unique event were to result from a mundane cause, there would be no established conjunction between the two, for that relies on past occurrences. Yet, in the antecedent of the above statement, the cause is the mundane event, by definition. It is in the reliance upon previous regularity that Hume’s constant conjunction theory finds is foundation, whereas his counter-factual idea finds causation in each single, distinct, and solely observed relation.
An example of how constant conjunction is useless while counter-factual can be applied is discerned if one first imagines a man who is thoroughly versed in the knowledge of fire and of trees and yet has absolutely no experience with or knowledge of lightning. Supposing that, one day, he sees a bolt of erratic white light descend from the sky and strike a tree, cleaving it and setting it afire. Because he fully understands the nature of trees and fire, and because he has never seen such resultant events occur spontaneously, this man is left with only the lightning as the cause of the destruction. He sees the lightning as being the most likely cause, not from past experiences with lightning, but due to the fact that had it not occurred, the tree would most likely have not ended up as charred splinters, for trees generally just do not do such things. Therefore, it is evident that constant conjunction can be useless in at least one case of causation, and counter-factual, alone, is directly required to draw some causal conclusion. Because of this difference in example, as well as the aforementioned logical difference derived from the connotations of Hume’s two causal theories, it is obvious that the two theories are not equivalent. They both offer good insight into the nature of cause and effect relations and, if used cautiously, could be perhaps the best ways to draw a conclusion from restricted evidence. They should not, however, be confused as identical.