  Then it simply becomes useful to refer to those objects which are not given in sensory experience – or at least not presently given – as ‘things-in-themselves’ since they are, by the causal criterion, real. Things-in-themselves are just the transcendent entities of the objective, three-dimensional world of everyday material objects, as well as the unobservable, theoretical entities postulated by contemporary science. Unsurprisingly, the reality of these entities is contested by a variety of related views, which Schlick classifies as ‘immanence’ philosophies. The most prominent immanence view is the kind of phenomenalism found in thinkers from John Stuart Mill to contemporaries like Joseph Petzoldt, Ernst Mach, and (as Schlick added in the second edition of General Theory …), Bertrand Russell. More curious, perhaps, is that Schlick also indicted his intellectual forebear, Hermann von Helmholtz, as an immanence philosopher. Basically, these thinkers all restrict reality to the given, so that reality consists exclusively of colors, tastes, and smells, as well as other sensations, presented in constantly changing combinations with one another. This is, of course, just to deny the reality of transcendent objects, thus abjuring the causal realism implicit in everyday and scientific talk of transcendent objects which exist and endure beyond momentary sensations. Instead, the immanence thinkers claim that all talk of transcendent objects consists entirely of discourse about complexes of sensations which exhibit more stability and constancy than others. Mach stated the common view of immanence philosophies that material bodies do not produce sensations, because bodies are, at bottom, nothing more than complexes of sensations (Schlick 2009, Sec. 25). Of course, immanence views differ among themselves in their efforts to identify which particular complexes of sensation are identified with everyday material bodies and scientific entities, especially when the latter are not perceived. 