The title of Walter Kaufmann's old gem says it all. Of course, Kaufmann was careful to qualify his title: Dostoevsky was not an Existentialist in any formal sense (but then, who is?); rather, his novella Notes From Underground was the "best introduction to Existentialism" that Kaufmann had ever encountered.
And he was definitely on to something; for Dostoevsky's revolt against scientific and materialistic reductions of human beings to "rational actors" prefigures Sartre's insistence that existence (being-in-itself) does not exhaust human possibilities. "Essence" (being-for-itself) remains a wild-card--even if, for Sartre, that wild-card signifies, at the end of the day, a "useless passion."
Sartre was himself an interesting amalgam of Dostoevsky and Tolstoy: refusing, like the former, to see the human being reduced to a "rational actor," Sartre likewise refused (in Tolstoyan fashion) to underestimate the human being qua rational actor.
Reading Sartre, one wonders whether George Steiner's formula "Tolstoy or Dostoevsky" ought not to be reinstated in a more inclusive vein: as with Black Liberation theologian James Cone's insistence that to choose between Martin Luther King, Jr. and Malcolm X is to make a choice that is false to the full experience of African American history, so to choose between Tolstoy and Dostoevsky is to make a choice that is false to the full experience of human history more generally.
A small amendment might do the trick: Tolstoy and/or Dostoevsky. Such is the Sartrean legacy to us all.
