The first argument by which to establish a dependence relation of morality on religion is that morality becomes rationally unstable if we do not have a way to assure ourselves that morality and happiness are consistent so that we do not have to do what is morally wrong in order to be happy; it concludes that we need belief in God to give us this assurance.

Kant is arguing not that a life committed to meeting the moral demand is impossible without belief in God, but that there is a certain kind of rational instability in such a combination—betraying a lack of rational fit.

What is the moral demand? What is moral obligation? Kant gives us, in the Groundwork of the Metaphysics of Morals, various formulations of what he takes to be the supreme principle of morality, namely the Categorical Imperative. Here are two of these formulations or formulas. The first states: “Act only in accordance with that maxim through which you can at the same time will that it become a universal law.” A maxim prescribes an action together with the reasons for, or the end to be produced by, that action.

Kant gives an alternative version of the first formula to make this point clearer: “Act as if the maxim of your action were to become by your will a universal law of nature.” Not a law of physical nature entailing loss of freedom—but nature has one feature that makes the analogy useful: nature is a system in which the same kind of cause produces the same kind of effect in a lawful way wherever and whenever it occurs. We can call any obligation that passes this universalizing test a “universal obligation.”

The second formula of the Categorical Imperative is the formula of the end-in-itself: “So act that you treat humanity, whether in your own person or in the person of any other, always at the same time as an end and never merely as a means.” Humanity should never be treated as a mere means. Kant is not forbidding using people, but we must never merely use. To treat another person as an end in herself is to share as far as possible her ends.

There is something common to the positions on the moral demand held by the Kantian, the Consequentialist, and any Virtue Theorist who takes impartial benevolence to be a virtue. The moral demand is that we treat each person as one, and no person as more than one, and we try to make the other’s purposes our purposes as far as we can, namely as far as the moral law itself allows. This account itself includes reference to the moral law in its final clause, and therefore does not explain the moral demand in a non-circular way.

Sometimes people who know Kant’s moral theory but do not know his moral theology wonder why he would bring in happiness at all, as the argument from providence requires. Doesn’t requiring a connection with happiness constitute a pollution of moral purity?

To reply to this worry, it’s helpful to see how Kant distinguishes his position from the views he attributes to the Stoics and Epicureans. The Stoics reduced happiness to virtue. The Epicureans held that virtue is simply what leads to happiness, and so in effect also reduced virtue to happiness. Kant objected to both, because we are not merely rational, but also creatures of sense and creatures of need. Our highest good is a union of virtue and happiness, which are two different things. Virtue is the disposition to live by duty or the moral law, and happiness is the satisfaction of our inclinations as a sum, or where everything goes the way we would like it to. (The Epicureans, in a real sense, fail to give us morality at all.)

Consider a case of conflict. Suppose I have an obligation to care for an aged parent even though I recognize it will detract from my happiness. Hare will argue later that not all the components of happiness are satisfactions of what Kant calls “inclinations,” and they are not all properly classified under the general heading of “pleasure.” So the difference between duty and happiness is not as stark as Kant pretends, but Hare will try to show that there are still basically two kinds of motivation for action, and not (as the Aristotelian proposes) finally only one.

Since we are both rational beings and creatures of sense and of need, our highest good, Kant says, requires a union of virtue and happiness. Since our morality gives us this end, the highest good, we must, if we are to pursue the morally good life in a way that is rationally stable, believe that this highest good is really (and not merely logically) possible. But we don’t see that we have the capacity to bring this highest good about. Nature, Kant says, is indifferent to our moral purposes, as far as we can tell from our sense experience. In order to sustain our belief in the real possibility of the highest good, we therefore have to postulate the existence of a “supersensible author of nature,” who can bring about the conjunction of happiness and virtue, and thus “morality inevitably leads to religion.”

Though Kant was not a divine command theorist, he did say throughout the corpus that we have to recognize our duties as God’s commands, because it is only if they are God’s commands that we can rationally believe in the moral possibility of the highest good, which is the end that morality itself gives to us.

Kant thus subscribes to the scholastic picture of the three roles of God as sovereign, distinguishing God’s legislative, executive, and judicial authority. On this picture God promulgates the law by command, runs the universe in accordance with this law, and then judges our success in keeping this law.

Not only Kant, but also the classical authors of the utilitarian tradition, have endorsed a version of the argument from providence. Mill said we need hope with respect to the government of the universe, if we are to sustain the moral life. Sidgwick recognized that the only way to reconcile enlightened self-interest with aiming at the maximum balance of happiness for all sentient beings present and future, whatever the cost to oneself, was to bring in a god who desires the greatest total good of all living things and will reward and punish in accordance with this desire. Belief in such a god is necessary, though he didn’t say this was sufficient reason to believe. He did recognize, though, that incorporating this belief would be a return to Paley’s utilitarianism (which preceded Bentham’s).

We could escape the force of the argument by thinking morality absurd, but if so it would be hard to sustain our attempt to live morally. Evil might lead one to think the world absurd in this way. Kant’s “On the Miscarriage of All Philosophical Trials in Theodicy” condensed his thoughts on the problem of evil into this short monograph about Job.

We need to persevere past the negative to the positive content in this volume (like the 1stCritique). Kant offers a kind of “transcendental theodicy.” Kant’s objective is to “deny knowledge so as to make room for faith.” The faith he wants to make room for is faith in God as legislator, ruler, and judge. The problem of evil is a problem for the claim that there is a God like this. Kant goes through three traditional theodicies ‘proper’ for each of these three roles, and shows that all nine fail. (This resembles the way he dismantled the ontological and cosmological and physico-teleological proofs for the existence of God). But then Kant says not only do we have no proof within the limits of the three roles, we also have no disproof. To attempt a disproof would transgress the limits of our insight just as much as the attempted proofs. But if there is no disproof within theoretical reason, the need of practical reason for the postulation of the divine wisdom prevails. This brings us to Job.

Job’s friends speak as though they were ingratiating themselves with God. Job alone is frank and sincere. He does not hide his doubts, but he also does not deceive himself about his own guilt. What God does in the story is to reveal (out of the whirlwind) the wisdom of the creation, and especially its inscrutability. God shows to Job the beautiful side of creation, but also its fearsomeness. Job founded his faith on his commitment to the moral life, Kant argued. If we are sure that we are under the moral law, then we are entitled to believe in the existence of a ruler of the world who makes the evil in the world (which we can’t deny) subordinate to the good.