Since the terms psychological hedonism and ethical hedonism are of great interest to some, and those terms appear to originate with Henry Sidgwick, it's probably helpful to have a thread on who Sidgwick was and what he was doing with his categories, and why.
Clearly there is relevance between the thought of the Utilitarians vs Epicurus. I personally consider Utilitarianism to have been a dead end and misapplication of Epicurus' philosophy, but there's always something to learn from history.
The following is an excerpt from Wikipedia
Sidgwick summarizes his position in ethics as utilitarianism "on an Intuitional basis".[10] This reflects, and disputes, the rivalry then felt among British philosophers between the philosophies of utilitarianism and ethical intuitionism, which is illustrated, for example, by John Stuart Mill's criticism of ethical intuitionism in the first chapter of his book Utilitarianism.
Sidgwick developed this position due to his dissatisfaction with an inconsistency in Jeremy Bentham and John Stuart Mill's utilitarianism, between what he labels "psychological hedonism" and "ethical hedonism". Psychological hedonism states that everyone always will do what is in their self-interest, whereas ethical hedonism states that everyone ought to do what is in the general interest. Sidgwick believed neither Bentham nor Mill had an adequate answer as to how the prescription that someone ought to sacrifice their own interest to the general interest could have any force, given they combined that prescription with the claim that everyone will in fact always pursue their own individual interest. Ethical intuitions, such as those argued for by philosophers such as William Whewell, could, according to Sidgwick, provide the missing force for such normative claims.
For Sidgwick, ethics is about which actions are objectively right.[11] Our knowledge of right and wrong arises from common-sense morality, which lacks a coherent principle at its core.[12] The task of philosophy in general and ethics in particular is not so much to create new knowledge but to systematize existing knowledge.[13] Sidgwick tries to achieve this by formulating methods of ethics, which he defines as rational procedures "for determining right conduct in any particular case".[14][15] He identifies three methods: intuitionism, which involves various independently valid moral principles to determine what ought to be done, and two forms of hedonism, in which rightness only depends on the pleasure and pain following from the action. Hedonism is subdivided into egoistic hedonism, which only takes the agent's own well-being into account, and universal hedonism or utilitarianism, which is concerned with everyone's well-being.[13][14]
As Sidgwick sees it, one of the central issues of ethics is whether these three methods can be harmonized with each other. Sidgwick argues that this is possible for intuitionism and utilitarianism. But a full success of this project is impossible since egoism, which he considers as equally rational, cannot be reconciled with utilitarianism unless religious assumptions are introduced.[14] Such assumptions, for example, the existence of a personal God who rewards and punishes the agent in the afterlife, could reconcile egoism and utilitarianism.[13] But without them, we have to admit a "dualism of practical reason" that constitutes a "fundamental contradiction" in our moral consciousness.[11]
Metaethics
Sidgwick's metaethics involve an explicit defence of a non-naturalist form of moral realism. He is committed to moral cognitivism: that moral language is robustly truth-apt, and that moral properties are not reducible to any natural properties. This non-naturalist realism is combined with an ethical intuitionist epistemology to account for the possibility of knowing moral truths.[16]
Esoteric morality
Sidgwick is closely, and controversially, associated with esoteric morality: the position that a moral system (such as utilitarianism) may be acceptable, but that it is not acceptable for that moral system to be widely taught or accepted.[17]
Bernard Williams would refer to Sidgwickian esoteric utilitarianism as "Government House Utilitarianism" and claim that it reflects the elite British colonialist setting of Sidgwick's thought.[18]
Philosophical legacy
According to John Rawls, Sidgwick's importance to modern ethics rests with two contributions: providing the most sophisticated defence available of utilitarianism in its classical form, and providing in his comparative methodology an exemplar for how ethics is to be researched as an academic subject.[19] Allen Wood describes Sidgwick-inspired comparative methodology as the "standard model" of research methodology among contemporary ethicists.[20]
Despite his importance to contemporary ethicists, Sidgwick's reputation as a philosopher fell precipitously in the decades following his death, and he would be regarded as a minor figure in philosophy for a large part of the first half of the 20th century. Bart Schultz argues that this negative assessment is explained by the tastes of groups which would be influential at Cambridge in the years following Sidgwick's death: Wittgensteinian ordinary language philosophers, the remnants of British idealism, and, most importantly, the Bloomsbury Group.[21] John Deigh, however, disputes Schultz's explanation, and instead attributes this fall in interest in Sidgwick to changing philosophical understandings of axioms in mathematics, which would throw into question whether axiomatization provided an appropriate model for a foundationalist epistemology of the sort Sidgwick tried to build for ethics.[22]