 The idea that justice and moral obligation do not depend on a free decree of God is a significant doctrine in Leibniz's philosophy. In the seventeenth and eighteenth centuries, a focal point of debate in moral philosophy centered on a version of the Euthyphro problem—between those who sided with Grotius and Leibniz in holding that moral goodness and obligation do not depend on God's will and those who held the opposite view, that moral goodness and obligation are as they are as a result of God's free choice. Two of the most important seventeenth-century proponents of the latter, voluntarist position are Thomas Hobbes and Samuel Pufendorf (1632–1694). Leibniz's objections to voluntarism became widely known in the early eighteenth century when a letter he wrote attacking voluntarism was appended to a new edition of Pufendorf's The Duty of Man and Citizen (1718). This anti-voluntarist tract, “Opinion on the Principles of Pufendorf” (written in 1706), contains one of his fullest discussions of justice. A full treatment of Leibniz's anti-voluntarism would take us too far afield, but a central criticism is that, in regarding moral goodness and obligation as dependent on God's free choice, voluntarism undermines the basis for our love of God (PW, “Opinion on the Principles of Pufendorf,” p. 71–2). If, as the voluntarist holds, moral goodness is an artifact of God, it is not an essential attribute of the divine nature. God therefore cannot be loved for His goodness.  Voluntarism thus subverts morality and religion because love of God is essential to both (for more in depth discussions of Leibniz's anti-voluntarism, see Schneewind 1998 (250–259) and Haakonssen 1996 (46–9)).