Abstract

Abstract The grammar of spatial and temporal concepts cannot, it is argued, be the same in their application to the (manifest) world as perceived and to the (nether) world of unobservable causes as modelled in physics. A parallel case is the dual meaning of colour words, for hues and for material dispositions. The keys to differentiating the two main ranges of uses of ?s? and ?t? are: differences in criteria of numerical and qualitative identity in the two ?worlds'; differences in the logic of indexicals in each context; the explanatory role of powers. The differences can be illustrated in a close analysis of the concept of velocity