In the second chapter of The Cement of the Universe, J.L. Mackie tries to unpack our concept of causation. His claim is that statements about causation are statements about necessity. The only kind of sufficiency that Mackie finds in causation is a weak sufficiency, ‘given the circumstances if x occurs, so will y.’ What he denies is that in calling something a cause we require anything about strong sufficiency, ‘given the circumstances, if y had not been going to occur, x would not have occurred.’ The idea is that strong sufficiency generally holds of causation, but it is not required for recognition of causation.
He uses the following intuition pump to try and persuade his readers. We are to imagine an indeterministic slot machine which may or may not give out a chocolate bar upon a coin being inserted. Whether or not the chocolate bar appears is entirely a matter of chance once the coin is inserted. In normal circumstances it is necessary to put a coin into the machine to get a chocolate, but it is not sufficient.
Imagine that you put in coin and receive a chocolate – lucky you. Mackie believes that in such a case we are inclined to say that inserting the coin caused the chocolate to appear. In this case, inserting the coin was weakly sufficient for receiving the chocolate, but it was not strongly sufficient: in the circumstances, if you did not receive a chocolate it would not mean that you had not inserted a coin.
I am totally not convinced that we would call the insertion of a coin a cause of receiving the chocolate in such a case. Does anyone else share my sentiments?