Although he spent most of his life as a philosopher, Spir never held a university appointment and his writings remained relatively unknown and unrecognized throughout his life. Indeed, Spir complained of a wall or conspiracy of silence ("das Totschweigen"). Yet, he had a significant influence on several eminent philosophers, scholars and writers such as Hans Vaihinger, Friedrich Nietzsche, William James, Leo Tolstoy and Rudolf Steiner. Vaihinger read Spir's "Thought and Reality" as soon as it was published (1873) and recalls that it made a "great impression". Nietzsche described him as "an outstanding logician" ("ein ausgezeichneter Logiker"). James makes several references to Spir in his "Principles of Psychology", for example when debating a certain Kantian issue he wrote, "On the whole, the best recent treatment of the question known to me is in one of A. Spir's works, his "Denken und Wirklichkeit"".