Humean definition of causality
coined a sceptical, reductionist viewpoint on causality that inspired the logical-positivist definition of empirical law that "is a regularity or universal generalization of the form 'All Cs are Es' or, whenever C, then E". The Scottish philosopher and economist believed that human mind is not equipped with the ability to observe causal relations. What can be seen is one event following another. The reductionist approach to causation can be exemplified with the case of two billiard balls: one ball is moving, hits another one and stops, and the second ball is moving.
David Hume listed three requirements for calling a relation causal:
universal association between X and Y,
time precedence of Y by X,
spatiotemporal connection between X and Y.
