The everyday sense of hedonism — pursuing sensual gratification — corresponds to the Cyrenaics, a minor ancient school, and almost not at all to Epicurus, whose name became a byword for luxury by a historical accident he would have found bewildering.
Epicurus did hold that pleasure is the good, but analysed pleasure in an unexpected way. The highest state is not intense enjoyment but ataraxia, freedom from disturbance, together with the absence of bodily pain. Once pain is removed, pleasure is at its maximum and can be varied but not increased — which means the elaborate pursuit of gratification is pointless. His practical advice followed: eat simply, since expensive tastes create needs that are hard to satisfy; avoid politics and its anxieties; and above all cultivate friendship, which he regarded as the greatest contributor to a happy life. He argued that fear of death and fear of the gods are the main sources of human misery, and that both dissolve under examination.
Distinguish two very different claims. Ethical hedonism says pleasure is what we ought to pursue; it is a claim about value, and it supplies the value theory underlying Bentham's utilitarianism. Psychological hedonism says pleasure is what we always in fact pursue; it is a claim about motivation. The second is widely rejected — people knowingly choose painful paths for the sake of others, or of truth, and the hedonist reply that they take pleasure in doing so risks making the theory unfalsifiable by counting anything anyone chooses as pleasure by definition.
The main objectionThe experience machine.
Nozick devised the decisive test. Imagine a machine that could give you any experience you wanted, indistinguishable from reality — a lifetime of accomplishment, love and pleasure, all simulated. You would not know you were plugged in. Would you connect for life?
Most people say no, and hedonism has trouble explaining why. If pleasure were the only intrinsic good, the machine would be strictly better than any real life, since it delivers more of the only thing that matters. The refusal suggests we value other things for their own sake — actually doing things rather than seeming to, genuine contact with reality, being a certain kind of person rather than merely feeling like one.
Hedonists have responses. Some argue the intuition reflects status quo bias, or distrust of the machine's reliability, rather than a considered judgement about value. Others accept the argument and move to desire-satisfaction or objective-list theories of wellbeing, which allow that several things matter intrinsically. Mill had already moved partway, distinguishing higher pleasures by kind rather than quantity — though critics note that if quality trumps quantity, something other than pleasure is doing the ranking, and the theory has quietly stopped being hedonism.