3 ideas
Clamence confesses his own vices in terms general enough that the listener recognizes himself in the portrait, and so is led to judge himself too. By accusing himself first he earns the right to judge everyone else, and he turns confession into a tool of domination rather than repentance. The self-accuser keeps the high ground: 'the more I accuse myself, the more I have a right to judge you.'
Seen through this lens, acts of kindness, courtesy, and charity are ways of staying 'above' others, of feeling superior and applauded, and are driven by vanity more than care. Clamence helped the blind across streets and defended widows and orphans because doing so let him stand on the summit and admire himself. Once you see the audience inside the good deed, including the audience of one, it becomes hard to trust your own motives.
Clamence argues that no one is innocent. Because every person carries hidden guilt, people rush to judge others so they will not be judged themselves, and they prefer to be passed over rather than acquitted. Since universal innocence is impossible, he says, the only honest position is to admit shared guilt, which he then turns into a new kind of power over others.