The Dialogues are a series of discussions about the rationality of religious belief between the fictional characters Cleanthes, Philo, and Demea. Demea represents religious dogmatism and insists that we cannot come to know the nature of God through reason. Philo, the philosophical skeptic, agrees with Demea that God is incomprehensible but insists that he might be morally corrupt. Cleanthes argues that we can know about God by reasoning from the evidence we find in nature.
Demea argues that although God clearly exists, we cannot know his nature, because God’s nature is beyond the capacity of human understanding. Philo seems to agree with him. Demea goes on to explain that God is the First Cause, meaning that the world operates on a system of cause and effect, so there must be an original cause to have started the world in motion, and that First Cause is God. But this still tells us nothing about God’s nature, which Cleanthes insists we can learn by examining nature. Cleanthes states that the only rational argument for God’s existence is one based on experience. The design and order of nature reveal that there must be an intelligent designer, or creator, whose intelligence resembles our own. Cleanthes also states that things that are very familiar and present to us need no reason to establish their truth, such as the knowledge that food nourishes the body.
Philo disagrees with Cleanthes and argues that just because the world is ordered, there is no reason to believe that this order is a result of intelligent design. He explains that the example of the design of the universe supposes an acceptance of cause and effect, which in turn supposes that the future will resemble the past. However, since there is nothing with which to compare our situation, we cannot assume the necessary connection based on past experience or other examples. Philo goes further, claiming that even if God is an intelligent designer, this fact does not explain why nature has order. Finally, even if the argument from design were valid, nature does not provide us with any knowledge about God other than that he designed it.
Philo next turns his attention to God’s possible moral attributes and whether we can discover these by examining nature. Together, Demea and Philo explain that the world is filled with evil. Philo says that if there is so much evil, there cannot be a God who is completely beneficent, or else he would have eliminated evil. If he cannot eliminate evil, he cannot be all-powerful. If he is unaware of the evil, he cannot be all-knowing. If nature itself provides evidence of God’s nature, then we must conclude that he doesn’t care about us at all and is therefore morally ambiguous. Demea leaves the room, upset by these claims.
Although Philo has successfully torn down Cleanthes’ argument from design, Philo finishes the dialogue by declaring that the ordered world obviously has some intelligence behind it and that this intelligence does in fact resemble human intelligence. His real disagreement, he claims, concerns how strong this resemblance really is. He then attacks religious dogma as both morally and psychologically harmful. The most rational position, he says, is a philosophical belief in some unknowable higher power. Finally, Philo tells Cleanthes that philosophical skepticism is the only proper route to true Christianity because it forces us to rely on faith instead of the false connection between reason and theism.
Hume clearly intends to point out that the question of God’s existence and the supposed religious origin of morals are in fact two different issues and that a positive stance on the first issue does not necessarily confirm the second. The true question is whether enough evidence exists in the world to prove that there is an infinitely good, wise, and powerful God from which morality naturally springs. Philo argues that there is not, and his explanation that the existence of evil poses a problem for this view of God is worth considering seriously. It seems impossible that an all-good, all-powerful, and all-knowing God could exist in a world as painful as ours. However, Cleanthes’ position also seems cogent. We don’t need to justify the existence of things that are universal truths. For example, we cannot prove that motion exists without referring to an example of motion itself. If both man and the universe exhibit form and order, we may logically consider that a similar intelligence lies behind both. However, from that claim we could argue that this intelligence, or God, possesses both good and evil, as man does.