 The failure of science indicators to function as definitions of scientific progress is due to the fact that they do not take into account the semantic content of scientific publications. To determine whether a work \(W\) gives a contribution to scientific progress, we have to specify what \(W\) says (alternatively: what problems \(W\) solves) and then relate this content of \(W\) to the knowledge situation of the scientific community at the time of the publication of \(W\). For the same reason, research assessment exercises may use science indicators as tools, but ultimately they have to rely on the judgment of peers who have substantial knowledge in the field.