 By dropping or mitigating some of the above principles, we get less minimalist versions of the sparse conception. For example, some have urged uninstantiated properties to account for features of measurement (Mundy 1987), vectors (Bigelow &amp; Pargetter 1991: 77), or natural laws (Tooley 1987), and some even that there are all the properties that can be possibly exemplified, where the possibility in question is causal or nomic (Cocchiarella 2007: ch. 12). In line with positions traditionally found in emergentism (see  §5.1),  Schaffer (2004) proposes that there are sparse properties as fundamental, and in addition, as grounded on them, the properties that need be postulated at all levels of scientific explanations, e.g., chemical, biological and psychological ones. Even Armstrong goes beyond minimalist strictures, when in his later work (1997) distinguishes between “first-class properties” (universals), identified from a minimalist perspective, and “second-class properties” (supervening on universals). All these positions appear to be primarily concerned with issues in the metaphysics of science (see  §5)  and typically display too short a supply of properties to deal with meaning and mental content, and thus with natural language semantics and the foundations of mathematics (see  §6).  However, minimalists might want to resort to concepts, understood as mind-dependent entities, in dealing with such issues (e.g., along the lines proposed in Cocchiarella 2007).