Causality and Time: An Introductory Typology Bert Leuridan * and Thomas Lodewyckx †‡ October 9, 2018 1 Introduction Causes precede their effects. Effects come after their causes. I strike a match; shortly after, it lights. John Jones has been smoking heavily during his adoles- cence; decades later, he develops lung cancer. An embryo inherits genes from both its parents; in the course of its subsequent ontogeny, it develops a range of phenotypic traits. It would not make sense to say that the lighting of the match was a cause of the striking, or that Jones’s lung cancer caused him to smoke, or that an organism’s phenotypic traits causally determine its genome. Propter hoc, ergo post hoc. At least, that’s what common sense tells us. The common sense idea that causes must precede their effects is fairly widespread in the philosophical literature. This is illustrated in the following quotes: Now even the most daring thinker would hardly recommend the consumption of omelettes as a way of inducing hens to have laid their eggs. Indeed, in this form of words, the absurdity of post- dating causes is flagrant. (Black, 1956, p. 58, original italics) It doesn’t matter whether the effect coincides with the last of its conditions, or immediately follows it. It doesn’t precede it; and when we are wondering which of two coexistent phenomena is the cause and which the effect, we rightly regard the question as answered if we can ascertain which of them came first. (Mill, 1843/1911, Book III, chapter V, §7) Causality is a notoriously difficult notion. What precisely does it mean to say that x causes y? The quest for a definition has haunted philosophers and * University of Antwerp, Centre for Philosophical Psychology † University of Antwerp, Centre for Philosophical Psychology and Ghent University, Centre for Logic and Philosophy of Science. The research for this paper was supported by the Research Foundation Flanders (FWO) through research project G056616N. ‡ We would like to thank Samantha Kleinberg and the reviewers for their constructive and helpful comments. 1