The two most fundamental sensations in life are pleasure and pain, and the difference between the two is the source of all motivation. Without clear definitions of these, any discussion of human behavior (not to mention morality) will have little to do with reality. And since this is a scientifically based system, we should start with the relevant biological principles.
Our bodies are rigged with sensors that detect harmful conditions. When one of those sensors is overloaded, we experience pain. The sensory neurons supply impulses to the brain, waking up the relevant problem solving linkages. When the harmful conditions go away, the painful stimuli subside, and that part of the brain goes back to its resting state. Pleasure seems to be just the cessation of pain. Neuroscientists have found nuclei in the brainstem (the periaqueductal gray and the raphé nuclei) that ease pain by triggering the release of natural pain-killers, as well as mediating the action of synthetic pain-killers. The same areas seem to be involved in sensations of pleasure.
So the common notion of pain and pleasure as total opposites is not correct — pain is too much stimulation, and pleasure is the reduction of pain. We only think of these as opposites because we only care about the difference between the two. As proof, we can go from pain to pleasure, and from crying to laughing, without going through any void between those "extremes". Hence it's just a matter of degree, not a difference in kind.
In this context we can easily understand the Hindu and Buddhist ideal of Nirvana, which is the cessation of all worldly wants. But westerners should understand that Nirvana is not detachment, and it is not denial. It is a matter of embracing the world, and resonating in harmony with the forces of nature. In a world that keeps moving, only in skillful motion are we at peace with ourselves and our neighbors. Somebody who is moving too quickly, or too slowly, or traveling in the wrong direction, is going to experience biologic insult, and that's not Nirvana.
For adults, there is another layer of complexity. When we were children, our parents used Pavlovian conditioning to associate pleasure with good behavior, and/or pain with bad behavior. If we are mature enough to be contemplating spirituality, these associations are permanently fixed in long term memory, and we continue displaying good behavior, long after the last time we actually got rewarded for it. The significance here is not that we get to re-evaluate what we were taught. If we search our souls for what is right, we can go no deeper than the influence of those who raised us. We might be able to work through some mixed messages, and reinterpret the lessons in the context of current issues. But we cannot change our fundamental outlooks. The significance is that as parents, we must instill values that will serve our children well, and we must pay particular attention to what they learn when they are very young. The way the brain categorizes information, each successive lesson is an amendment to the previous one. If the framework is bad, later lessons about goodness will not steer the child back onto the right path, but will merely teach the child how to feign goodness. Then it will take a radical change in the child's environment to signal that a fundamentally different pattern has to be learned. Likewise, a well-established sense of goodness allows the child to see the good even in bad situations. So it's worth the effort to make sure that the fundamental attitude is correct. And it is the duty of all members of society to reinforce the good values instilled by the parents. It's easy to make a friend by affording a child leeway that her parents do not, but it's much easier on the child, now and later, if the rules do not change. Hence we all must hold ourselves to the highest moral standards with respect to our children, setting examples that will serve them well to follow.
Above all of that, there is one more level of complexity that is responsible for the way we actually think of pain and pleasure on a daily basis — it's the forces of hope and fear. We are motivated not so much by the pain that we are feeling now, but by the fear that things are getting worse, and we will do anything for the hope that things will be better tomorrow.
The physiology of hope and fear is simple. If we think that things are getting better, our brains release endorphins to muffle the aches and pains that distract us. In essence, the brain will continue to search for solutions, until either the problem goes away, or the brain realizes that the problem will go away, the way things are going, in which case the brain just shuts off the alarms (i.e., releases endorphins to suppress the painful stimuli). Fear of an unmitigated risk, on the other hand, accentuates sensitivity, as the brain knows that it needs to wake up every problem solving mechanism it has.
And how do we nurture hope?
Only when we see progress, in ourselves and in the world around us, are we comfortable believing that what troubles us now will not be a problem in the future. So we have to continue to get better. We have to take better care of ourselves, to keep our personal needs out of the way as much as possible, and we have to work together with everyone else to build a better world.
In the more general sense, when we have a sense of purpose in life, it isn't pain that we feel — that's just information that helps us address our needs. But without a sense of purpose, it's all just senseless pain and suffering. So pain is the punishment for people who are living meaningless lives, not trying to build a better world, and instead, just sit around feeling sorry for themselves and wondering why a loving God would subject them to such misery. Their lives wouldn't be miserable if they were doing God's work.
Summary
- All members of society must reinforce morals taught to children.
- Progress gives us hope, the best motivation of all.
- With a sense of purpose, pain & suffering go away.