  Properties are entities that are meant to play different theoretical roles. For instance, one role they are meant to play is that of being the semantic values of predicates. Another role is that of accounting for similarity and the causal powers of things. But there is no reason why these different roles should be played by one and the same kind of entity. When philosophers nowadays discuss the issue of universals they normally think of properties as entities that account for the similarity and causal powers of things. Properties in this sense are sometimes called sparse properties, as opposed to abundant properties (the distinction between sparse and abundant properties comes from Lewis 1983). Sparse properties are those which would be sufficient to account for the similarity and causal powers of things, and to characterise them completely and without redundancy. In what follows it is assumed, for the sake of example, that properties like being square and being scarlet count as sparse.