- Alfred Adler was an Austrian physician and psychotherapist who founded the school of individual psychology. He broke away from Freud and rejected his theory of sexuality as the primary motivator of human behavior.
- Adler believed that all human behavior is motivated by a desire for superiority and perfection. He saw feelings of inferiority as the root cause of neurosis and the driving force behind people's striving for superiority.
- Adler developed theories around birth order and its impact on personality, organ inferiorities and compensation, masculine protest, and social interest. He believed that understanding an individual's subjective experiences and feelings of inferiority was key to analyzing their behavior and psychological issues.