Addiction science is at an impasse. Rates of addiction are rising. Translational results from decades of research are minimal. Meanwhile theories of addiction multiply and compete, fomenting disagreement about something as apparently simple as how addiction should be defined. How to move forward? I aim to sketch a new paradigm. I start by asking a basic question. What are all theories of addiction trying to explain? The answer is the puzzle at the core of addiction. Drug use in addiction carries life-shattering costs. Yet people with addiction keep using drugs. Why? All theories of addiction must answer to this why-question. But not all answers must apply equally to all people who are addicted. This simple idea has a host of important consequences. The first is a diagnosis of the impasse in addiction science as a conflation of explanans and explanandum. The second is a way to move beyond the impasse through recognition of heterogeneity: theories can divide and conquer rather than compete, thereby dovetailing with good clinical practice. The third is that the line between addiction and ordinary drug use cannot be drawn independently of context and values. The paradigm is therefore as humanistic as it is scientific.