which philosopher held the view that pleasure is the sole good
Hedonism Ethical hedonism is the idea that all people have the right to do everything in their power to achieve the greatest amount of pleasure possible to them. It is also the idea that every person's pleasure should far surpass their amount of pain. Ethical hedonism is said to have been started by Aristippus of Cyrene, a student of Socrates. He held the idea that pleasure is the highest good.[2]
Moral development Notions of morality development have been developed over centuries, the earliest came from philosopher like Confucius, Aristotle, and Jean-Jacques Rousseau, who all took a more humanist perspective and focused on the development of the conscience and sense of virtue. In the modern day, empirical research has explored morality through a moral psychology lens by theorists like Sigmund Freud and its relation to cognitive development by theorists like Jean Piaget, Lawrence Kohlberg, B. F. Skinner, Carol Gilligan and Judith Smetana.