How did Karl Jaspers’s friendship with Martin Heidegger end?

The friendship between Karl Jaspers and Martin Heidegger, which flourished during the 1920s, ultimately ended due to Heidegger’s decision to join the Nazi Party in 1933.21

Following the rise of the Nazi regime, Heidegger actively supported the party and its policies, including the implementation of the Führerprinzip (leadership principle) at the University of Freiburg. In contrast, Jaspers, whose wife was Jewish, became a target of Nazi persecution, facing exclusion from university councils and eventually a total ban on his work.23

The ideological and moral divide between the two philosophers became irreconcilable. In the post-war period, Jaspers remained deeply critical of Heidegger’s political choices and his refusal to publicly disavow his Nazi past. Jaspers famously characterized Heidegger’s way of thinking as "unfree, dictatorial, and incapable of communication," viewing it as pedagogically disastrous.2