Philosopher's disease and its antidote: Perspectives from prenatal behavior and contagious yawning and laughing.

Accounts of behavior, including imitation, often suffer from philosopher's disease: the unnecessary, inappropriate, theoretically driven explanation of behavior in terms of cognition, rationality, and consciousness. Embryos are perversely unphilosophical and unpsychological, starting to move before they receive sensory input. Postnatal contagious yawning and laughing indicate that pseudo-imitative behavior can occur without conscious intent or other higher-order cognitive process.