 Lakatos proposed a middle-way, in which Kuhn’s socio-psychological tools were replaced by logico-methodological ones. The basic unit of appraisal is not the isolated testable theory, but rather the “research programme” within which a series of testable theories is generated. Each theory produced within a research programme contains the same common or “hard core” assumptions, surrounded by a “protective belt” of auxiliary hypotheses. When a particular theory is refuted, adherents of a programme do not pin the blame on their hard-core assumptions, which they render “irrefutable by fiat”. Instead, criticism is directed at the hypotheses in the “protective belt” and they are modified to deal with the problem. Importantly, these modifications are not random—they are in the best cases guided by the heuristic principles implicit in the “hard core” of the programme. A programme progresses theoretically if the new theory solves the anomaly faced by the old and is independently testable, making new predictions. A programme progresses empirically if at least one of these new predictions is confirmed.