 This fundamental insight has been the source of a lasting theoretical challenge: if amenable to analysis, the role of evidence as supporting (or infirming) hypotheses has to be grasped by more nuanced tools than plain logical entailment. As emphasized in a joke attributed to American philosopher Morris Raphael Cohen (1880–1947), logic textbooks had to be divided in two parts: in the first part, on deductive logic, unwarranted forms of inference (deductive fallacies) are exposed; in the second part, on inductive logic, they are endorsed (see Meehl 1990, 110). In contemporary philosophy, confirmation theory can be roughly described as the area where efforts have been made to take up the challenge of defining plausible models of non-deductive reasoning. Its central technical term— confirmation—has often been used more or less interchangeably with “evidential support”, “inductive strength”, and the like. Here we will generally comply with this liberal usage (although more subtle conceptual and terminological distinctions are sometimes drawn).