Pleasure describes the broad class of mental states that humans and other animals experience as positive, enjoyable, or worth seeking. It includes more specific mental states such as happiness, entertainment, enjoyment, ecstasy, and euphoria. In psychology, the pleasure principle describes pleasure as a positive feedback mechanism, motivating the organism to recreate in the future the situation which it has just found pleasurable. According to this theory, organisms are similarly motivated to avoid situations that have caused pain in the past.
The experience of pleasure is subjective and different individuals will experience different kinds and amounts of pleasure in the same situation. Many pleasurable experiences are associated with satisfying basic biological drives, such as eating, exercise, sex or defecation. Other pleasurable experiences are associated with social experiences and social drives, such as the experiences of accomplishment, recognition, and service. The appreciation of cultural artifacts and activities such as art, music, and literature is often pleasurable.
In recent years, significant progress has been made in understanding the brain mechanisms underlying pleasure. One of the key discoveries was made by Kent C. Berridge who has shown that pleasure is not a unitary experience. Rather, pleasure consists of multiple brain processes including liking, wanting and learning subserved by distinct yet partially overlapping brain networks. In particular, this research has been helped by the use of objective pleasure-elicited reactions in humans and other animals such as the behavioral ‘liking’/‘disliking’ facial expressions to tastes that are homologous between humans and many other mammals.
Recreational drug use can be pleasurable: some drugs, illicit and otherwise, directly create euphoria in the human brain when ingested. The mind's natural tendency to seek out more of this feeling (as described by the pleasure principle) can lead to dependence and addiction. Berridge and Robinson have proposed that addiction results from drugs hijacking the ‘wanting’ system through a sensitization of the mesolimbic dopamine system.
Philosophical views 
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Epicurus and his followers defined the highest pleasure as the absence of suffering and pleasure itself as "freedom from pain in the body and freedom from turmoil in the soul". According to Cicero (or rather his character Torquatus) Epicurus also believed that pleasure was the chief good and pain the chief evil.
In the 12th century Razi's "Treatise of the Self and the Spirit" (Kitab al Nafs Wa’l Ruh) analyzed different types of pleasure, sensuous and intellectual, and explained their relations with one another. He concludes that human needs and desires are endless, and "their satisfaction is by definition impossible."
Philosophies of pleasure 
The pleasure center is the set of brain structures, predominantly the nucleus accumbens, theorized to produce great pleasure when stimulated electrically. Some references state that the septum pellucidium is generally considered to be the pleasure center, while others mention the hypothalamus when referring to the pleasure center for intracranial stimulation. Certain chemicals are known to stimulate the pleasure centers of the brain. It has been suggested that physical exertion can release endorphines in what is called the runner's high, and equally it has been found that chocolate and certain spices, such as from the family of the chilli, can release or cause to be released similar psychoactive chemicals to those released during sexual acts.
Pleasure as a uniquely human experience 
There has been debate as to whether pleasure is experienced by other animals rather than being an exclusive property of humankind. On the one hand, Jeremy Bentham (usually regarded as the founder of Utilitarianism) and Beth Dixon both argue that they do—the latter, however, in a carefully worded manner. People who believe in human exceptionalism might argue that it is a form of anthropomorphism to ascribe any human experience to animals, including pleasure. Others view animal behaviour simply as responses to stimuli; this is the way behaviourists look at the evidence, Pavlov's dogs (or rather his explanation of their behaviour) being the best-known example. However, it may be argued that we simply cannot know whether animals experience pleasure, and most scientists, indeed, prefer to remain neutral while using anthropomorphisms as and when they need them. It appears, though, that those who recognise emotions in other animals are in the ascent: many ethologists, for example Marc Bekoff, are prepared to draw the conclusion that animals do experience emotions, though these are not necessarily the same as human emotions.
Masochists are those who derive pleasure from receiving pain. The existence of masochism complicates the commonly-held view that pleasure, as a positive experience, is fundamentally opposite pain, a negative experience. Masochism is context-dependent: masochists enjoy certain kinds of pain in certain situations.
See also 
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- False pleasure
- Felicific calculus, an attempt to calculate pleasure
- Flow (psychology)
- Paradox of hedonism
- Kringelbach, M.L; K.C. Berridge (2010). Pleasures of the brain. Oxford University Press. ISBN 0-19-533102-8.
- Berridge, K.C., Kringelbach, M.L. (2008) Affective neuroscience of pleasure: Reward in humans and other animals. Psychopharmacology 199, 457-80.
- Videos of Pleasure-elicited Reactions.
- Robinson, T.E., Berridge, K.C. 1993 The neural basis of drug craving: an incentive-sensitization theory of addiction. Brain Res Brain Res Rev. 18(3):247-91.
- The Forty Principal Doctrines, Number III.
- Letter to Menoeceus, Section 131-2.
- About the Ends of Goods and Evils, Book I, From Section IX, Torquatus sets out his understanding of Epicurus's philosophy.
- Haque, Amber (2004). "Psychology from Islamic Perspective: Contributions of Early Muslim Scholars and Challenges to Contemporary Muslim Psychologists". Journal of Religion and Health 43 (4): 357–377 . doi:10.1007/s10943-004-4302-z.
- Counsels and Maxims, Chapter 1, General Rules Section 1.
- Walsh, Anthony (1991). The Science of Love – Understanding Love and its Effects on Mind and Body. Prometheus Books. ISBN 0-87975-648-9.
- Kandel ER, Schwartz JH, Jessell TM. Principles of Neural Science, 4th ed. McGraw-Hill, New York (2000). ISBN 0-8385-7701-6
- Bentham, Jeremy (1996). An Introduction to the Principles of Moral Legislation. Oxford: Oxford University Press. ISBN 978-0-19-820516-6.
- Ethics & the Environment, Volume 6, Number 2, Autumn 2001, pp. 22-30, Indiana University Press, Johns Hopkins University Press, see also: Emotion in animals
- Horowitz A. 2007. Anthropomorphism., In M. Bekoff, ed., Encyclopedia of Human-Animal Relationships, pp 60-66, Greenwood Publishing Group, Westport, CT.
- Do animals have emotions?, From The Sunday Times, August 24, 2008.
Further reading 
- Paul Bloom. How Pleasure Works: The New Science of Why We Like What We Like (2010) 280 pages. Draws on neuroscience, philosophy, child-development research, and behavioral economics in a study of our desires, attractions, and tastes.
- M.L. Kringelbach. The pleasure center: Trust Your Animal Instincts (2009). Oxford University Press. ISBN 978-0-19-532285-9. An general overview of the neuroscience of pleasure.