 A third view, which seems more attractive than either of the two mentioned so far, is to expand the notion of a physical property that is in play in formulations of physicalism. For example, one might treat the properties of abstract objects as topic-neutral in something like the sense discussed in connection with Smart and reductionism above (see section 3.1). Topic-neutral properties have the interesting feature that, while they themselves are not physical, but are capable of being instantiated in what is intuitively a completely physical world, or indeed what is intuitively a completely spiritual world or a world entirely made of water. If so, it becomes possible to understand physicalism so that the reference to ‘physical properties’ within it is understood more correctly as ‘physical or topic-neutral properties’. 