You can move around the definition of pleasure, but then you end up with situations where pain as a means to pleasure is indistinguishable from pain as equal to pleasure, which undermines the whole premise of hedonism (that only pleasure has value).
How could you possibly end up in a situation where pain is equal to pleasure? I think pain would only be considered positive when it leads to greater pleasure.
Epicurus' philosophy is based on the theory that all good and bad derive
from the sensations of what he defined as pleasure and pain: What is good
is what is pleasurable, and what is bad is what is painful. If pain is
chosen over pleasure in some cases it is only because it leads to a greater
pleasure. Epicurus explicitly warned against overindulgence because it often
leads to pain.
Although Epicurus has been commonly misunderstood to advocate the rampant
pursuit of pleasure, his teachings were more about striving for an absence
of pain and suffering, both physical and mental, and a state of satiation
and tranquility that was free of the fear of death and the retribution of
the gods.
Humans have a wide range of pleasures, of varying degrees of richness and sophistication. People sometimes object to hedonism on the grounds that it makes us no better than swine in the mud. But I think that reflects a poor opinion of humanity. Don't we get pleasure from symphonies, poetry, and great works of art?
Epicurus himself said he could be content with water, bread, weak wine and a "pot of cheese".
hedonism can look great when it's practiced by people who believe that the greatest pleasure comes from appreciating art. but it can look horrible for example in the case of suicide bombers, who i believe to be rational agents (i don't believe that they're mentally handicapped or on drugs or something). these are men who are completely convinced that they're doing the victims a great favor and that they will be rewarded with the highest pleasure imaginable. so in this case, the definition of pleasure has been moved so far that what is meant to be an expression of the highest pleasure imaginable is indistinguishable (to an outside observer) from pain.
maybe that's too extreme of an example, but it illustrates the point that the hedonist notion of good and bad is vastly ambiguous and can lead to undesirable situations, most notably in cases where people try to optimize for the afterlife, but also in varying degrees in other cases. so i think it ultimately it fails in practice as a moral philosophy.
I also think hedonism tends to stigmatize pain to an impractical degree. i think experiencing and accepting pain is an important part of life, not because it leads to greater pleasure, but because pain is a part of the human condition and there's value in observing it and recognizing its importance. in regards to art, there can't be catharsis without pain, so it doesn't make sense to me to say that pleasure is somehow better than pain in that sense. i think pain and pleasure are two sides of the same coin.
