 Bealer (1982) distinguishes between conception 1 properties, or qualities, and conception 2 properties, or concepts (understood as mind-independent). With a different and now widespread terminology, Lewis (1983, 1986b) followed suit, speaking of a sparse and an abundant conception of properties. According to the former, there are relatively few properties, namely just those responsible for the objective resemblances and causal powers of things; they cut nature at its joints, and science is supposed to individuate them a posteriori. According to the latter, there are immensely many properties, corresponding to all meaningful predicates we could possibly imagine and to all sets of objects, and they can be assumed a priori. (It should be clear that “few” and “many” are used in a comparative sense, for the number of sparse properties may be very high, possibly infinite). To illustrate, the sparse conception admits properties currently accepted by empirical science such as having negative charge or having spin up and rejects those that are no longer supported such as having a certain amount of caloric, which featured in eighteenth century chemistry; in contrast, the abundant conception may acknowledge the latter property and all sorts of other properties, strange as they may be, e.g., negatively charged or disliked by Socrates, round and square or Goodman’s (1983) notorious grue and bleen. Lewis (1986b: 60) tries to further characterize the distinction by taking the sparse properties to be intrinsic, rather than extrinsic (e.g., being 6 feet tall, rather than being taller than Tom), and natural, where naturalness is something that admits of degrees (for example, he says, masses and charges are perfectly natural, colors are less natural and grue and bleen are paradigms of unnaturalness). Much work on such issues has been done since then (see entries on  intrinsic vs. extrinsic properties  and  natural properties).