Moral psychology is a field of study in both philosophy and psychology. Historically, the term "moral psychology" was used relatively narrowly to refer to the study of moral development. Moral psychology eventually came to refer more broadly to various topics at the intersection of ethics, psychology, and philosophy of mind.
In philosophy, moral responsibility is the status of morally deserving praise, blame, reward, or punishment for an act or omission in accordance with one's moral obligations. Deciding what (if anything) counts as "morally obligatory" is a principal concern of ethics. Philosophers refer to people who have moral responsibility for an action as "moral agents". Agents have the capability to reflect upon their situation, to form intentions about how they will act, and then to carry out that action.
In ethical philosophy, ethical egoism is the normative position that moral agents ought to act in their own self-interest. It differs from psychological egoism, which claims that people can only act in their self-interest. Ethical egoism also differs from rational egoism, which holds that it is rational to act in one's self-interest. Ethical egoism holds, therefore, that actions whose consequences will benefit the doer are ethical. Ethical egoism contrasts with ethical altruism, which holds that moral agents have an obligation to help others.
Ethics or moral philosophy is a branch of philosophy that "involves systematizing, defending, and recommending concepts of right and wrong behavior". The field of ethics, along with aesthetics, concerns matters of value; these fields comprise the branch of philosophy called axiology. Ethics seeks to resolve questions of human morality by defining concepts such as good and evil, right and wrong, virtue and vice, justice and crime. As a field of intellectual inquiry, moral philosophy is related to the fields of moral psychology, descriptive ethics, and value theory.
The trolley problem is a series of thought experiments in ethics and psychology, involving stylized ethical dilemmas of whether to sacrifice one person to save a larger number. The series usually begins with a scenario in which a runaway tram or trolley is on course to collide with and kill a number of people (traditionally five) down the track, but a driver or bystander can intervene and divert the vehicle to kill just one person on a different track. Then other variations of the runaway vehicle, and analogous life-and-death dilemmas (medical, judicial etc.
