In the autograph letter of 1911 Vaihinger congratulates Karl Groos on his recent appointment to a chair at Tübingen, and thanks him for sending an article and comments about his newly-published Die Philosophie des Als Ob. He then discusses Kant’s early use of a kind of ‘Als Ob-Betrachtung’ in his Opus Postumum, referring Groos to pages in the new book and inviting his further comments. In the letter dated 1916 (presumably dictated because by now he was nearly blind) Vaihinger sets out in tabular form a hierarchy of five conceptual levels first distinguished by him in an article from 1878, “Das Entwicklungsgesetz der Vorstellungen über das Reale”. He then maps these levels on to those found in Die Philosophie des Als Ob, explains them more fully, and asks for Groos’s opinion. In the third letter he discusses the connections between the Theory of Play famously developed by Groos and his own Philosophy of ‘As If’. A strong collegial tone runs through these letters, as though Vaihinger feels he has quite as much to learn from Groos as the other way round. As he writes in the second letter: “Es gibt in meinen Augen überhaupt keine Philosophie ohne Psychologie”.
Hans Vaihinger (1852-1933), celebrated neo-Kantian philosopher and founder-editor of the journal Kant-Studien. These letters are about academic matters, and they include discussion of Vaihinger’s masterpiece, Die Philosophie des Als Ob (The Philosophy of ‘As If’), which was first published in 1911, the year of the first letter. The book had largely been written 30 years earlier as Vahinger’s Habilitationsschrift under the supervision of Ernst Laas, entitled ‘Logische Untersuchungen. I. Teil: Die Lehre von der wissenschaftlichen Fiktion’. When failing eyesight forced Vaihinger to relinquish his professorship at Halle in 1906, he turned to the manuscript again.