  But, the PAO also builds on Lange’s position in non-trivial ways. Vaihinger’s autobiographical essay “The Origin of the Philosophy of ‘As If’” points to two further significant influences, Arthur Schopenhauer and Charles Darwin. Vaihinger’s interest in Schopenhauer was sparked by the doctrine that the intellect is “a mere tool in the service of the will” (Schopenhauer 1958, 2:205). This view is based in part on Schopenhauer’s metaphysics, according to which the ultimate nature of reality is nothing other than a suprapersonal, aimless, quasi-volitional striving or “will.” Schopenhauer holds that this “will” expresses itself empirically in the striving of organic beings to preserve their individual existence, and the intellect has accordingly developed as a mere tool to aid more complex organisms in this task. Vaihinger believed that Darwin’s theory of natural selection had provided an empirical grounding for Schopenhauer’s hypothesis (PAO xviii). This was crucial, since Vaihinger’s own Kantianism prevented him from endorsing Schopenhauer’s speculative vitalist metaphysics (PAO xvii). At the same time, Vaihinger comes to view Kant’s doctrine of the essential limits of our cognition through this Schopenhauerian-Darwinian lens: the “limitations of human knowledge,” he says, are “a necessary and natural result of the fact that thought and knowledge are originally only a means, to attain the Life-purpose, so that their actual independence signifies a breaking-away from their original purpose; indeed, by the fact of this breaking-loose, thought is confronted by impossible problems” (PAO xviii). Vaihinger will use this idea to motivate his own fictionalism, and to provide a radical reinterpretation of Kantianism.