Practical reason thumb|Portrait of Immanuel Kant, who proposed an argument for the existence of God from morality In his Critique of Pure Reason, German philosopher Immanuel Kant stated that no successful argument for God's existence arises from reason alone. In his Critique of Practical Reason he went on to argue that, despite the failure of these arguments, morality requires that God's existence is assumed, owing to practical reason.Oppy 2006, pp. 372–373 Rather than proving the existence of God, Kant was attempting to demonstrate that all moral thought requires the assumption that God exists.Guyer 2006, p. 234 Kant argued that humans are obliged to bring about the summum bonum: the two central aims of moral virtue and happiness, where happiness arises out of virtue. As ought implies can, Kant argued, it must be possible for the summum bonum to be achieved. He accepted that it is not within the power of humans to bring the summum bonum about, because we cannot ensure that virtue always leads to happiness, so there must be a higher power who has the power to create an afterlife where virtue can be rewarded by happiness.
Practical reason thumb|Portrait of Immanuel Kant, who proposed an argument for the existence of God from morality In his Critique of Pure Reason, German philosopher Immanuel Kant stated that no successful argument for God's existence arises from reason alone. In his Critique of Practical Reason he went on to argue that, despite the failure of these arguments, morality requires that God's existence is assumed, owing to practical reason.Oppy 2006, pp. 372–373 Rather than proving the existence of God, Kant was attempting to demonstrate that all moral thought requires the assumption that God exists.Guyer 2006, p. 234 Kant argued that humans are obliged to bring about the summum bonum: the two central aims of moral virtue and happiness, where happiness arises out of virtue. As ought implies can, Kant argued, it must be possible for the summum bonum to be achieved. He accepted that it is not within the power of humans to bring the summum bonum about, because we cannot ensure that virtue always leads to happiness, so there must be a higher power who has the power to create an afterlife where virtue can be rewar!ded by happiness.