Defensiveness in the depth-psychology corpus is not a unitary concept but a contested field traversed by at least three distinct theoretical registers. In the somatic-trauma tradition — represented most extensively by Ogden, Levine, and Porges — defensiveness is first and foremost a neurobiological inheritance: an orchestrated suite of phylogenetically ancient survival responses (fight, flight, freeze, shutdown) that become pathological not through their initial deployment but through their inflexibility and chronicity after threat has passed. Here the body is both the archive of failed defense and the site of its renegotiation. Porges anchors this view in polyvagal theory, proposing that ‘faulty neuroception’ — inaccurate threat appraisal — produces maladaptive defensive activation even in objectively safe environments. A second register, prominent in Miller’s motivational interviewing literature, treats defensiveness as an interpersonal phenomenon: a predictable client response to confrontational or blame-attributing clinical styles, amenable to reframing and alliance repair. A third, more psychodynamic register — glimpsed in Yalom, Flores, and Addenbrooke — situates defensiveness within group dynamics and object-relations, where it indexes resistance to self-disclosure, devaluation of feedback, and the use of addiction or spiritual practice as protective avoidance. What unites these registers is agreement that defensiveness, however expressed, represents an attempt at self-protection whose original adaptive logic must be honored before any therapeutic transformation becomes possible.