For example, simplified models used in the physical sciences are often formally false, but nevertheless close enough to the truth to furnish useful insight; this is understood as a form of idealization.

Vaihinger describes human knowledge as erroneous and contradictory and asks how to explain the fact that one can still arrive at the right thing based on these false assumptions.

Vaihinger's answer is that the assumptions are a practically useful fiction, and that knowledge can therefore only be pragmatically substantiated by the success that is achieved in its application.

The Philosophy of 'As if' influenced Sándor Ferenczi in his 1913 letter to Sigmund Freud,[6] and Alfred Adler in his 1912 book Über den nervösen Charakter.

[1] The philosopher Moritz Schlick wrote that Vaihinger's description of his philosophy as a form of "idealist positivism" was one of its many contradictions.