Abstract: According to knowledge-first psychology, you had the concept of knowledge before you had the concept of belief. During this knowledge-only stage, your beginning speech sufficed for testimony. Your ability to assert presented an opportunity to thwart the testimony of others. When the tattle-tale told your mother that p, you denied p. Simple denial often suffices to prevent punishment. This negative reinforcement of insincere denials leads to more lying. Alas, you were soon caught by a higher mind. Later, you, too, acquired the concept of belief. This helped you predict and manipulate action on the basis of belief and desire – and lower the risk of your lies being detected. Just as walking does not entirely displace crawling, knowledge-lies continue to be deployed in circumstances in which belief-lies are overkill. Recognizing knowledge-lies in adults is more difficult because sophisticated sabotage of knowledge could so easily be understood as subtle belief-lies. Thus knowledge-first psychology provides pure specimens – such as yourself as a child.