  To make these arguments we have to distinguish the truly pathological gambler, whose life is dominated (and typically wrecked) by gambling, from merely habitual gamblers. Habitual gamblers might engage in gambling more than they feel they should, or periodically lose more than they can afford, but there is a qualitative difference between this population and the population of genuinely addicted gamblers. This qualitative difference is detected by observing behaviour and rating the results of questionnaires. However, if we classify gamblers according to quantitative measures alone, we miss the reason why different groups behave differently. The reason is a causal process. The brains of the real addicts don’t work like the brains of the merely troubled; thinking of addiction merely in terms of habitual behaviours will not let us make the discriminations among gamblers that neuroscientific evidence detects.