Lask was born in Austrian Galicia, as a son of Jewish parents. After completing his philosophical education at Freiburg, he was made lecturer at Heidelberg in 1905, and he was elected professor there just before the outbreak of World War I. When war began in 1914 Lask immediately volunteered. Since, as a Heidelberg professor, he would have been regarded as indispensable on the home front, he did not have to enlist. But, conscientious and idealistic, Lask believed that he had an obligation to serve his country. Lask was made a sergeant and sent to Galicia on the Eastern front, despite a frail constitution and severe myopia—which also meant that he could not shoot, but he still felt obliged to remain at the front. Lask died during the war, not far from the city of his birth, in the Galician Campaign. Wilhelm Windelband refused to request his return to Heidelberg as indispensable to philosophy.