Differential geometry was not Finsler's research topic for long since he moved to take up set theory. Finsler's habilitation thesis was submitted to the University of Cologne in 1922 and the following year he have his inaugural lecture on Are there contradictions in mathematics.
Kaugalian geometry ay hindi Finsler's research topic para sa mahaba dahil siya inilipat sa set up ng teorya. Finsler's habilitation sanaysay ay isinumite sa University of Cologne sa 1922 at ang mga sumusunod na taon na siya ay may kanyang panayam sa pagtanggap sa Mayroon bang kontradiksyon sa matematika.