 Sometimes the new objects introduced by conditional principles do not make demands on reality; when that happens, they are said to be thin (for example, directions only require that there be parallel lines). However, when the new objects introduced by sufficiency statements make more substantial demands on reality, the objects are considered thick. Suppose \(Rab\) asserts \(a\) and \(b\) are spatiotemporal parts of the same cohesive and naturally bounded whole. Then \(a\) and \(b\) become specifications for physical bodies via the following principle: \(Rab \Rightarrow \mathrm{Body}(a) \! =\! \mathrm{Body}(b)\). In this case, the principle “makes a substantial demand on the world” because it requires checking that there are spatiotemporal parts constituting a continuous stretch of solid stuff (just looking at the spatiotemporal parts does not suffice to determine whether they constitute to a body; see Linnebo 2018, 45).