The argument from morality is an argument for the existence of God. Arguments from morality tend to be based on moral normativity or moral order. Arguments from moral normativity observe some aspect of morality and argue that God is the best or only explanation for this, concluding that God must exist. Arguments from moral order are based on the asserted need for moral order to exist in the universe. They claim that, for this moral order to exist, God must exist to support it. The argument from morality is noteworthy in that one cannot evaluate the soundness of the argument without attending to almost every important philosophical issue in meta-ethics. German philosopher Immanuel Kant devised an argument from morality based on practical reason. Kant argued that the goal of humanity is to achieve perfect happiness and virtue (the summum bonum) and believed that an afterlife must be assumed to exist in order for this to be possible, and that God must be assumed to exist to provide this. Rather than aiming to prove the existence of God, however, Kant was simply attempting to demonstrate that all moral thought requires the assumption that God exists, and therefore that we are entitled to make such an assumption only as a regulative principle rather than a constitutive principle (meaning that such a principle can guide our actions, but it does not provide knowledge). In his book Mere Christianity, C. S. Lewis argued that "conscience reveals to us a moral law whose source cannot be found in the natural world, thus pointing to a supernatural Lawgiver." Lewis argued that accepting the validity of human reason as a given must include accepting the validity of practical reason, which could not be valid without reference to a higher cosmic moral order which could not exist without a God to create and/or establish it. A related argument is from conscience; John Henry Newman argued that the conscience supports the claim that objective moral truths exist because it drives people to act morally even when it is not in their own interest. Newman argued that, because the conscience suggests the existence of objective moral truths, God must exist to give authority to these truths. Contemporary defenders of the argument from morality are Graham Ward, Alister McGrath and William Lane Craig. General form All variations of the argument from morality begin with an observation about moral thought or experiences