 Skepticism about moral responsibility, or what is more commonly referred to as moral responsibility skepticism, refers to a family of views that all take seriously the possibility that human beings are never morally responsible for their actions in a particular but pervasive sense. This sense is typically set apart by the notion of basic desert and is defined in terms of the control in action needed for an agent to be truly deserving of blame and praise. Some moral responsibility skeptics wholly reject this notion of moral responsibility because they believe it to be incoherent or impossible. Others maintain that, though possible, our best philosophical and scientific theories about the world provide strong and compelling reasons for adopting skepticism about moral responsibility. What all varieties of moral responsibility skepticism share, however, is the belief that the justification needed to ground basic desert moral responsibility and the practices associated with it—such as backward-looking praise and blame, punishment and reward (including retributive punishment), and the reactive attitudes of resentment and indignation—is not met. Versions of moral responsibility skepticism have historically been defended by Spinoza, Voltaire, Diderot, d’Holbach, Priestley, Schopenhauer, Nietzsche, Clarence Darrow, B.F. Skinner, and Paul Edwards, and more recently by Galen Strawson, Derk Pereboom, Bruce Waller, Neil Levy, Tamler Sommers, and Gregg D. Caruso. 