Apart from Zosima, Alyosha is the most moral character in the novel, and the strength and clarity of his faith are the moral center of the novel. For Alyosha to have faith in Dmitri is not surprising, because Alyosha has faith in human nature. On the other hand, there is a sense in which, within the scope of the novel, the great philosophical conflicts that run through the story are all riding on the question of Dmitri’s guilt or innocence. Thus, if Alyosha places his faith in Dmitri and is proved wrong, the idea of faith will be thrown into doubt.

Ivan’s collapse into madness at the end of this section demolishes his cold dignity and reveals the terrifying emptiness at the heart of his philosophy. At the same time, his crisis brings some of the central ideas of the novel into direct conflict. As the novel progresses, Ivan continually resists the notion that he bears any moral responsibility for the actions of other human beings, saying instead that people are only responsible for their own actions. But his conversations with Smerdyakov gradually illustrate for him the role he played in enabling Smerdyakov to murder Fyodor Pavlovich. Ivan is therefore forced to accept the universal burden of sin for the first time, and it is the agony of this burden that leads to his mental breakdown. In a sense, Ivan’s skepticism is fueled by his general distrust of humanity. He withdraws into his detached intellectualism in part because he is unable to love other people, and wants to remain separate from them. Smerdyakov’s revelation that Ivan’s philosophy enabled him to murder Fyodor Pavlovich finally makes clear to Ivan the extent to which people are involved in one another’s lives. While illuminating the terrifying consequences of Ivan’s amoralism, Smerdyakov’s crime also shatters the walls Ivan has built around himself, and, in a way, the rest of humanity comes flooding in on him. Without the consolation of faith, Ivan cannot handle this burden. His hallucination of the devil, like the revelation of Smerdyakov’s guilt, shows him the nature of a world without God, but having so thoroughly rejected God, Ivan is left defenseless. His breakdown results from the collision between the psychology of doubt and the idea of moral responsibility. Ivan could endure one. He cannot endure both.

Smerdyakov’s motivations for killing Fyodor Pavlovich are vague. Smerdyakov believes Ivan wanted him to kill Fyodor Pavlovich. But he has other motivations as well. Smerdyakov may be living Ivan’s philosophy that if there is no God, all is permitted. He may also kill for the money, or out of his own hatred of Fyodor Pavlovich. Finally, Smerdyakov may simply feel a desire to do evil. Allegorically, the murder signifies the logical extreme of Ivan’s arguments. Smerdyakov shares Fyodor Pavlovich’s brutish wickedness, and so, in a sense, Fyodor Pavlovich is killed by his own loathsome way of living. Ivan’s conviction that good and evil are fraudulent categories, and that no one has any moral responsibility to anyone else, has facilitated the destruction of one amoral monstrosity by another. The deeply moral Ivan loses his mind when confronted with the horror of this development, as apparently does Smerdyakov, whose unmourned suicide is the final cry of terror and pain to come from the novel’s exploration of the nihilism of disbelief.