John Leslie Mackie was an Australian philosopher, originally from Sydney. He is perhaps best known for his views on meta-ethics, especially his defence of moral skepticism. However, he has also made significant contributions to philosophy of religion, metaphysics, and philosophy of language.
Mackie discusses his concept of an INUS condition, a term in a disjunction of conjunctions, the whole of which constitutes a necessary and sufficient condition. As an account clarifying the way people typically think about causation, it's hard to beat. As an account of causation, it's wide open to objection and improvement. To be fair, Mackie explicitly intended it to be the former.