Thanatos

Meaning: In Freud's later psychoanalytic theory, behavior is driven by two broad instincts. Eros is the life instinct, covering survival, sex, and love; its energy is the libido. Thanatos is the death instinct, an unconscious drive toward aggression, destruction, and a return to a lifeless state. Turned outward it appears as aggression or violence; turned inward, as self-destructive behavior. Both arise in the id, while the ego and superego redirect or restrain them, sometimes through defense mechanisms such as displacement.

On the MCAT: Passages or questions describe a person and ask which Freudian idea fits. Aggression, destructiveness, or repeated self-harming risk-taking points to Thanatos, while pleasure-seeking, bonding, or self-preservation points to Eros. The term also appears beside id, ego, superego, libido, and the pleasure principle in answer choices. No calculation is involved; the task is classification.

Common confusion: Thanatos is an unconscious drive in a theory, not a conscious wish to die. It is also not the id: the id is the psychic structure, and Eros and Thanatos are the instincts that fuel it. Aggression is its outward expression, not a full synonym. Many modern psychologists do not treat it as established.