1. Walter Lippmann argued that people form "pictures inside our heads" and rely on stereotypes to understand the world, as most knowledge comes indirectly through limited and filtered sources.
2. These simplified mental pictures and stereotypes are influenced by media and culture and often fail to accurately reflect reality. They can be manipulated for political propaganda.
3. Lippmann was skeptical about the ability of the public to make informed decisions in the modern mass society, and argued elites must guide public opinion, in contrast to democratic ideals of an engaged citizenry.