A search for justification and the impossibility of justification are recurrent motifs in the philosophy of Sartre. His philosophy is one of the incarnations of problematism and of the ambiguity of contemporary thought (for Man does seem, to the contemporary mind, to be ambiguous).
justificationsquotes
If I have exhausted the justifications, I have reached bedrock and my spade is turned. Then I am inclined to say: ‘This is simply what I do.