Norman utilizes philosophy, ethics, and psychology to investigate what makes an idea bad, why people are susceptible to misinformation and perilous beliefs, and what can be done to debunk these notions. Cleverly employing the language and ideas of immunology, he likens bad ideas and fallacies to pathogens that can "infect" minds. In his view, extreme ideologies, conspiracy theories, and fact-resistant politics can hijack a mind much like a virus infects a cell. He introduces the concept of "cognitive immunology," the ways in which the mind can identify, eliminate, or at least limit the influence of false and harmful ideas. Critical thinking, questioning, and common sense can function as mental antibodies. Norman offers a 12-step program for cognitive-immunity health. Bad ideas and the bad behavior they cause have a long history and won't easily retreat. In the eighteenth century, Voltaire warned, "Those who can make you believe absurdities can make you commit atrocities." Fortunately, an antidote to false information and dangerous doctrines already exists: truth. As with a vaccine, the challenge is to convince everyone to accept it.