The concept of futility in medicine refers to the incapability of an intervention to achieve its goal. Futility determinations form the basis for withholding and withdrawing life-sustaining interventions. Criticisms of attempted futility definitions relate to inconstant probability and value judgements concerning the goal pursued. This variability frustrates efforts to define futility. Language modifications and procedural approaches, both important ancillary measures, inherently lack the ability to resolve this difficulty. Beneath the notion of futility lie foundational factors whose revised understanding is required (...) to advance a definition. These factors include autonomy, death and the goals of medicine. Reconsidering the essence and influence of foundational factors is necessary to move beyond a seemingly irresolvable problem. In this essay, I assert that defining futility is not pointless but rather possible, necessary and unavoidable. With this assertion, I respond to the criticisms of futility. These responses together with a corrective understanding of foundational factors lead to a definition of futility. This definition balances respect for patients’ autonomy whilst allowing for interventions that do not undermine the essence of medicine and integrity of those practising it. Defining futility is an exercise in necessity requiring renewed perceptual foundations. (shrink)