 According to this use of the term, reduction is a relation of actual theory-succession, such that reductions happen at a certain time, namely, when scientists did bring it about. Often, philosophers employ the term ‘reduction’ in this sense, thereby designating an activity of scientists, or the outcome of such an activity. Whether or not a theory actually becomes the successor of another theory will depend not only on logical and metaphysical features of the respective theories, but also on pragmatic and epistemic aspects. The most relevant of these aspects are to be captured in a rational reconstruction, which plays a major role in some models of reduction.