Freud's instinct theory and Bowlby's attachment theory are generally seen as oppositional approaches. Most crucially, the two theories sharply differ on the question of internal vs. external origins of trauma: whether trauma originates from intra-psychic conflict between innate instincts (Freud), or from various degrees of relational deficiencies in the attachment figure's attentiveness and subsequent protection of the child from actual harm (Bowlby). This disagreement is often deemed completely unbridgeable. This paper, however, views the two theories as two links in a lineage of ideas rather than two opposites, as it follows the gradual shift of psychoanalytic emphasis from innate instincts to external objects; through objects to the Self; and from phantasy relationship to the crucial impact of actual relationships.
Adah Sachs (Wed,) studied this question.