The war has forced Ukrainian leaders like President Zelensky and Kiev’s mayor, Vitali Klitschko, to face decisions of existential proportions. Should they stand up to Putin, thus risking the lives of themselves and their citizens, or surrender, thus compromising their identity and the very existence of their country? It’s the type of question that existentialists like Jean Paul Sartre thought was impossible to answer by following reason alone. It’s precisely when it’s unclear what the right choice is, that the radical freedom and moral responsibility of human beings is revealed, writes Gordon Marino.