Do the first two years of life really determine a child's future development? Are human beings, like other primates, only motivated by pleasure? And do people actually have stable traits, like intelligence, fear, anxiety, and temperament? This text takes on the assumptions behind these questions, in an attempt to prove them mistaken. Scientists, as well as lay people, tend to think of abstract processes - like intelligence or fear - as measurable entities, of which someone might have more or less. This approach, in Kagan's analysis, shows a blindness to the power of context and to the great variability within any individual, subject to different emotions and circumstances. "Infant determinism" is another widespread and dearly held conviction that Kagan contests. This theory - with its claim that early relationships determine lifelong patterns - underestimates human resiliency and adaptiveness, both emotional and cognitive (and fails to account for the happy products of miserable childhoods, and vice versa). The last of Kagan's targets is the pleasure principle, which, he argues, can hardly make sense of unselfish behaviour impelled by the desire for virtue and self-respect - the wish to do the right thing.