Humanity has given few questions more thought than, "What is happiness?" What stands between us and an answer to this deceptively complex question is the problem of subjectivity -- happiness means different things to different people. Through the course of investigation by myriad disciplines among science and the humanities, it has become clear that happiness means different things to different fields as well.

To behaviorists, happiness is a cocktail of emotions we experience when we do something good or positive. To neurologists, happiness is the experience of a flood of hormones released in the brain as a reward for behavior that prolongs survival. According to the tenets of several major religions, happiness indicates the presence of God.

Philosophers have investigated happiness more thoroughly than anyone. They've boiled the debate over happiness down to a battle between two basic views, hedonia and eudaimonia. The former, hedonia, is arguably the more famous (or notorious) of the two, though both find their roots in classical Greek philosophy.

The hedonistic view of well-being is that happiness is the polar opposite of suffering; the presence of happiness indicates the absence of pain. Because of this, hedonists believe that the purpose of life is to maximize happiness, which minimizes misery. Over the years, hedonism has developed something of a bad image, as its focus is on propagating pleasure through any means available, including sexuality, excessive consumption, alcohol, drugs and other targets of religious and societal scorn [source: Waterman].

On the other side of the debate is eudaimonia, a term that combines the Greek words for "good" and "spirit" to describe the ideology. Eudaimonia defines happiness as the pursuit of becoming a better person. Eudaimonists do this by challenging themselves intellectually or by engaging in activities that make them spiritually richer people.

The distinction between the two comes down to whether happiness is a destination (the hedonic view) or a journey (the eudaimonic philosophy). Put another way, hedonism is the belief that happiness is derived externally, while eudaimonism expresses the idea that happiness comes from within.

Although at first glance, it would seem that the apparently nobler eudaimonia should triumph over hedonism as the proper explanation for happiness. After all, under eudaimonia, acts of generosity, kindness toward others and cultivating natural talents are prized over pursuits that produce the fleeting happiness associated with hedonism, like accumulating wealth. But it's here that we arrive at a paradox, and the reason neither hedonia nor eudaimonia have managed to claim victory as the explanation for happiness: To be generous toward others, mustn't one first accumulate some sort of wealth? Having the money the hedonist may prize can lead to the generosity the eudaimonist treasures [source: Konow and Earley].

Perhaps the distinction of what constitutes happiness should be left to the individual. After all, anxiety, a contradiction to happiness, might surface when you don't follow your own values -- whatever they may be. As the philosopher Albert Camus put it, "But what is happiness except the simple harmony between a man and the life he leads?" [source: Thinkexist].