In this thesis, I argue that Kant's Moral Argument gives good grounds to reject Schopenhauer's pessimism. I begin by defining pessimism as the view that "life is not choiceworthy," and dispelling some initial objections to it. Having established that pessimism doesn't succumb to obvious objections, I develop three lines of argument that tell in favor of it, each articulated in a chapter of its own that explains how Schopenhauer reconceives the categories of, in order, will, goodness, and death. Schopenhauer’s overall argument moves from will to goodness to death; and in the third and final section of the thesis I demonstrate how Kant's Moral Argument undercuts the crucial assumption about death on which his case for pessimism depends (i.e. mortalism). I conclude by rejecting an evidentialist objection to the Moral Argument, according to which evidence provides the only justifiable grounds for believing in anything, including, crucially, in a just afterlife.