Intelligence is usually thought of as the ability to think and learn, but in a rapidly changing world there is another aspect of cognitive skill that may be even more important: the ability to reconsider and unlearn what we have learned. In our everyday lives, many of us prefer the comfort of conviction to the discomfort of doubt. We listen to ideas that make us feel good rather than ideas that make us think deeply. We view disagreement as a threat to our ego rather than an opportunity to learn. We surround ourselves with people who agree with our conclusions, when we should be drawn to those who challenge our thought process. We think too much like preachers defending their sacred beliefs, prosecutors trying to prove the other side wrong, and politicians campaigning for approval. We think too little like scientists seeking truth. Intelligence is not a cure, it can be a curse: being good at thinking can make us bad at reconsidering. The smarter we think we are, the more unaware we can be of our limitations. With clear ideas and solid evidence, Grant explores how we can embrace the joy of being wrong, bring nuance to impulsive conversations, and build schools, workplaces, and communities that foster lifelong learning. Think Again shows that we don't have to believe everything we think or internalize everything we feel. It's an invitation to let go of ideas that no longer serve us. It's time to value mental flexibility, humility, and curiosity over foolish fixity. If knowledge is power, then knowing what we don't know is wisdom.