Hedonism is an ideology, that was originally promoted by Jeremy Bentham, and which, in modern times, has been promoted by David Pearce.
According to hedonism, the ultimate goal of all life is pleasure. Some form of hedonism are egoistic; utlilitarian hedonism, however, considers the greatest pleasure for greatest number of people to be the ideal. Quite a few people equate hedonism with sexuality and having a very loose or liberal view of the morality of sex. Many more advanced forms of hedonism concentrate however on spiritual, intellectual, or otherwise non-sexual forms of pleasure.
One school, grouped around Bentham, defends a quantitative approach. Bentham believed that the value of a pleasure could be quantitatively understood. Essentially, he believed the value of pleasure to be its intensity multiplied by its duration - so it was not just the number of pleasures, but their intensity and how long they lasted that must be taken into account.
Other proponents, like Mill, argue a qualitative approach. Mill believed that there can be different levels of pleasure - higher quality pleasure is better than lower quality pleasure. Mill also argues that simpler beings (he often refers to pigs) have an easier access to the simpler pleasures; since they do not see other aspects of life, they can simply indulge in their lower pleasures. The more elaborate beings tend to spend more thought on other matters and hence lessen the time for simple pleasure. It is therefore more difficult for them to indulge in such "simple pleasures" in the same manner.
Abolition of Displeasure
The Abolitionist Society is a transhumanist group calling for the abolition of suffering in all sentient life through the use of advanced biotechnology. Their core philosophy is negative utilitarianism. David Pearce is a theorist of this perspective and he believes and promotes the idea that there exists a strong ethical imperative for humans to work towards the abolition of suffering in all sentient life.