  One may now wonder, however, what is to be made of Vaihinger’s near exclusive emphasis in PAO on fictions in the natural sciences and mathematics. After all, the theorizing in fundamental physics is a rather different matter than determining how to find a meal, and even if such theories turn out to be useful down the line, it seems that life would (and does) manage just fine without them. Here, Vaihinger relies on another Darwinian idea, which he calls the “Law of Preponderance of the Means over the End,” according to which “means which serve a purpose often undergo a more complete development than is necessary for the attainment of their purpose” (PAO xxix). In the language of contemporary evolutionary biology, scientific thought is like a “spandrel.” At the same time, Vaihinger is keen to emphasize the connection between scientific theorizing and more humdrum cognitive processes. He adopts the broadly Kantian view that what is given to us in experience is merely a “chaos of sensations” (PAO 117), which needs to be ordered and refined by the logical functions of thought, or categories. For example, the repeated co-occurrence of sensations of a branching shape and sensations of green leads the psyche to postulate a relation of substantial inherence between a thing or substance (the tree) and its attribute (green) (PAO 122–23). However, he argues in a manner evocative of Berkeley, the notion of a substance is incoherent since it implies the existence of a bare substrate with no properties whatsoever (PAO 125–26). The fiction is nevertheless justified, he suggests, because it facilitates the recognition of regularities in the occurrences of our sensations, and the communication of these regularities to others (PAO 130). Given that our most immediate relation to the world is thus mediated by the categories (which also include the relations of part-whole, cause-effect, inter alia), it is natural to suppose that these fictions will resurface in our more sophisticated theories, e.g., in the form of the atom (a simple material substance). Vaihinger is not suggesting that genuine knowledge that serves no particular practical aim is impossible; but he is suggesting that our total theoretic image of the world is ultimately limited by those fictions that have been preserved as most adaptive for our basic practical aims (PAO 130).