Hedonism

Since ancient times, there have been philosophers advocating hedonism, the idea that the good life is the life with the most pleasure and least pain.

But new technology should make it clear that this is not true. In 1954, psychologists James Olds and Peter Milner were doing research on rats brains, and they accidentally placed an electrode in a rat’s pleasure and reward center, the so-called limbic system.  Later, they wired rats so they could press a lever and stimulate the brain's pleasure center directly, and rats did this as much as 5,000 times an hour. If they were allowed to, the rats would die of starvation, because they would continue to press this lever rather than eating. This study became the basis for later research about serotonin and dopamine, and the endorphins, the chemicals associated with pleasure. 

This sort of machine refutes the ethical theory of hedonism. The life that with the most pleasure would be a life attached to this machine, with constant stimulation to the pleasure center of the brain, and with intravenous feeding and other medical care to insure that you live as long as possible. But no one would call this a good life.  

In the past, some philosophers were able to believe that the best life is the life with the most pleasure, only because all pleasures were the side-effect of some natural activity -- such as eating, friendship, sex, or learning.  Once we see that it is possible to have pleasure detached from any natural activity, it is absolutely clear that pleasure itself is not the essence of the good life.