  Mach is not a phenomenalist under normal uses of this term, but this certainly requires investigation. First, to whatever extent he was a phenomenalist, he was a ‘scientific’ phenomenalist: his ideas were not derived from philosophical skepticism but through application of the results of psychology and evolutionary theory. He provides clues as to how we should understand his infamous “elements”—they are related to the thought of Fechner and Ewald Hering. Secondly, he advocated that physics should describe relations of experience as much as possible; in his time this was termed ‘phenomenological physics’. This was clearly meant as a methodological suggestion, arising out of the way he thought physics could best respond to the challenges presented to it by the life sciences.  Thirdly, he writes that his ideas were the same as Avenarius who had approached questions of the relationship between the psychical and the physical from a physicalistic perspective. Although Mach undoubtedly adopts a sensationalist basis, this foundation is not crucial for Mach. He recognizes the possibility of other foundations: