 As we shall see, the main rival philosophical theories of progress propose absolute criteria, such as problem-solving capacity or increasing truthlikeness, that are applicable to all developments of science throughout its history. On the other hand, rationality is a methodological concept which is historically relative: in assessing the rationality of the choices made by the past scientists, we have to study the aims, standards, methods, alternative theories and available evidence accepted within the scientific community at that time (cf. Doppelt, 1983, Laudan, 1987; Niiniluoto 1999a). If the scientific community \(SC\) at a given point of time \(t\) accepted the standards \(V\), then the preference of \(SC\) for theory \(T\) over \(T'\) on evidence \(e\) was rational just in case the epistemic utility of \(T\) relative to \(V\) was higher than that of \(T'\). But in a new situation, where the standards were different from \(V\), a different preference might have been rational. 