Full title: Mistakes Were Made (But Not by Me): Why We Justify Foolish Beliefs, Bad Decisions, and Hurtful Acts
"Mistakes Were Made (But Not by Me)" is a collection of cognitive biases which result in people practically never feeling guilt, even when they clearly make mistakes, commit crimes or immoral acts. There's always a reason and an explanation in their minds for why they act the way they act. A reason that "gives them permission" or even dignifies them in their own eyes.
The book describes various mechanisms of how it happens and how we lie to others, but also to ourselves.
The tricky thing with cognitive biases is that some of them are so sneaky that they work even if you know full well what they are, how they work, and when you're aware that they're at play. Still, it's always good to be self-aware. Even if you fall victim to one of the mechanisms, it won't be as bad, and it will be easier to get back on track.