The two strongest urges are firstly to seek pleasure, in all its myriad forms, and secondly to evade suffering, in all its myriad forms. The primordial glass half full and glass half empty of the human condition. These are the two sides of the hedonistic imperative, and are perhaps the most important motivations guiding the development of technology. Technology, and I use the word in its broadest sense, can satisfy these urges either by helping to eliminate suffering or by helping to induce pleasure. Technology to reduce suffering has throughout history largely consisted of the vast and complex fields of medicine and agriculture. On the other side of the fence, for the induction of pleasure, we find intoxicants and pharmaceuticals of other classes, as well as, arguably, every technological development that can be turned to conquest and control. Not all pleasures are good in the moral sense, or perhaps it is better to say that given our deeper origins in an animal world that runs red in tooth and claw, many of the chemical incentives inherent to our biology are triggered only through selfish and damaging acts.
There are nonetheless many pleasures that can be attained without causing harm or resorting to advanced forms of technology. Completing challenging work, triggering the evolved response to pattern and surprise that is humor, simply being present in an attractive location, participating in the puzzle palace of human interactions, physical or otherwise, and so forth. Altering the operation of our brains to induce pleasure without the need to undertake much of that work was a fairly early innovation, however. The point of much of technological progress is to achieve better results with less effort, after all. The logical end of that line is wireheading or a life science equivalent yet to be designed: an augmentation in the brain, a button that you push, and the system causes you to feel pleasure whenever you want. There are numerous other alternatives in the same technological genre that seem plausible, such as always-on happiness, regardless of circumstances.
This sort of thing makes many people nervous, and, sadly, rarely for useful reasons. One doesn't have to look much further than the continued efforts to make mood-altering drugs illegal to see a panoply of bad motivations and perverse incentives exhibited front and center. Not every drug user becomes an addict, and self-destruction through addiction is clearly something that people do to themselves, only aided by the drug. A drug is an enabling technology, like a hammer, and neutral in and of itself. There remains considerable uncertainty today over who is more or less prone to addiction, and why, though there are plenty of addictive games against which you can test yourself in that way, such as those in which the makers gleefully exploit the effects of variable reinforcement on the human mind.
That said, I suspect that even the most self-controlled of individuals has sufficient self-doubt to be wary of the advent of implementations of wireheading that might be, say, a hundred times better, cheaper, and safer than today's most influential mood-altering drugs. What would you do in the presence of that potential option to substitute for the hedonic treadmill of work and reward? Little Heroes by Norman Spinrad is a worthy, albeit partial, fictional exploration of that question, and I recommend it. It is worth asking yourself "why not gain control of my mind in this way?" - and then follow your own answers to their logical ends. That exercise will probably reveal a great deal about how you view the world and your place in it.
Reliable, safe, on-demand pleasure (or confidence, or feelings of well-being, or happiness) achieved through technologies such as wireheading is a topic that has been comprehensively explored in fiction and philosophy, and is very slowly trickling into the real world via some forms of early, only weakly effective pharmaceutical products. There is little I can add to that library here that hasn't been said well many times over. What I will say is that to my eyes this is actually the less interesting and less consequential of the two sides of the hedonistic imperative. It is the elimination of suffering, not the gaining of pleasure, that, when taken to its conclusions, will lead to a world and a humanity changed so radically as to be near unrecognizable.
Paradise engineering is a catch-all term for the creation and large-scale use of technology to build a world that satisfies the hedonistic imperative. For me at least, pleasure on demand is a nebulous, potentially dangerous, and much less important goal when compared to the concrete list of forms of suffering that we might address, especially when given that for each of these pains and lacks we can envisage the necessary technologies and changes in some detail. The hedonic treadmill may well be inextricably tied to freedom in its purest sense: the freedom to make your own choices implies the freedom to make mistakes, and pleasure and its absence are an important part of the mental machinery by which we measure our use of time and effort. Suffering, however, is not necessary in this model. Thus I see the primary task of paradise engineers as being to take the list of suffering in some approximate order from greatest and most widespread harm to least and most localized harm, and work on solutions until such time as there is no more meaningful suffering. By this I mean solutions to the actual problems, the root cause of suffering, rather than any form of shortcut akin to wireheading or other forms of augmentation of feeling. Selectively blocking all unwanted physical pain is one response to the suffering caused by an incurable fatal degenerative disease, for example, but it isn't a good response.
It might surprise some that the greatest cause of human suffering is not the inhumanity with which all too many people treat one another, individually and collectively. Nor is it the related deficits in the organization of our societies: war, kleptocracy, repression, the enforced poverty that results when the bottom rungs of the ladder of growth are removed. The greatest cause of suffering receives the least attention. It is aging, the simple biological wear and tear of the body and the structures of the brain that support the mind. It affects everyone, and it causes drawn out pain, fear, and misery, alongside the loss of dignity, opportunity, and vigor - and ultimately the loss of the self as the mind decays. A staggering number of people are presently suffering in many ways because of aging. To the degree that we think of death as a loss and a form of suffering, then we should be prompted by the fact that aging is by far the greatest cause of death in our species.
This then, is the next goal for paradise engineering: to bring aging under medical control, and to reduce the cost of that control to the point at which everyone can live indefinitely in youthful health. It could be feasible within decades, given great enough support for the necessary research and development, as we all age for the same reasons, and identical mass therapies for billions could be produced with the greatest of economies of scale. Control of aging is not the first goal undertaken by paradise engineers, however, which is to say that paradise engineering has been taking place for some time. Many important incremental goals were achieved over the course of the past half century, for example: progress in agricultural technology sufficient to make famine impossible, save through human neglect and corruption; greater control over infectious disease; and many others.
After hunger and aging, there is still the other half of infectious disease to deal with, however. There are also the thousands of forms of internal failure of human biochemistry and biology unrelated to aging or infection. Ultimately the medical community seeks complete control over our molecular biochemistry, sufficient to eliminate all defects. At present a look to the future suggests that this goal will compete with the development of machine alternatives to biological systems, and humans will become hybrids of engineered, cultivated biology and artificial nanoscale machinery that will work with, enhance, or replace portions of our biology. Aging and disease will be banished, while malfunctions and breakages will be both far less common and cause only inconvenience when they do happen. We will have successfully defeated all of the most common sources of physical pain and dysfunction, either by remodeling the chassis of our biology, or by adding guards to protect it from harm.
Suffering is not only human, however. The natural world from which we evolved continues to be as bloody, terrible, and rife with disease as it ever was. Higher animal species are certainly just as capable of experiencing anguish and pain as are we humans, and the same is true far further down into the lower orders of life than we'd like to think is the case. We ourselves are responsible for inflicting great suffering upon animals as we harvest them for protein - an industry that is now entirely unnecessary given the technologies that exist today. We do not need to farm animals to live: the engineering of agriculture has seen to that. The future of paradise engineering could, were we so minded, start very soon with an end to the farming and harvesting of animals. That would be followed by a growing control over all wild animal populations, starting with the lesser numbers of larger species, in order to provide them with same absolute control of health and aging that will emerge in human medicine. Taken to its conclusions, this also means stepping in to remove the normal course of predator-prey relationships, as well as manage population size by controlling births in the absence of aging, disease, and predation.
Removing suffering from the animal world is a project of massive scope, as where is the line drawn? At what point is a lower species determined to be a form of biological machinery without the capacity to suffer? Ants, perhaps? Even with ants as a dividing line, consider the types of technology required, and the level of effort to distribute the net of medicine and control across every living thing in every ecosystem. Or consider for a moment the level of technological intervention required to ensure a sea full of fish that do not prey upon one another, and that are all individually maintained in good health indefinitely, able to have fulfilling lives insofar as it is possible for fish. Artificial general intelligences and robust molecular manufacturing technologies, creating self-replicating machinery to live alongside and inside every living individual in a vast network of oversight and enhancement might be the least of what is required.
At some point, and especially in the control of predators, the animal world will become so very managed that we will in essence be curating a park, creating animals for the sake of creating animals, simply because they existed in the past - the conservative impulse in human nature that sees us trying to turn back any number of tides in the changing world. It seems clear that the terrible and largely hidden, ignored suffering of the animal world must be addressed, but why should we follow this path of maintaining what is? What good comes from creating limited beings for our own amusement, when that same impulse could go towards creating intelligences with a capacity equal or greater than our own? Creating animals, lesser and limited entities that will be entirely dependent on us, to be used as little more than scenery, seems a form of evil in a world in which better choices are possible.
Given this, my suspicion is that when it comes to the animal kingdom, the distant future of paradise engineering will have much in common with the goals of past religious movements and today's environmentalist nihilists, those who preach ethical extinction as the best way to end suffering. Animals will slowly vanish, their patterns recorded, but no longer used. If animals are needed as a part of the world in order to make the human descendants of the era feel better, then that need can be filled through simulations, unfeeling machinery that plays the role well enough for our needs. The resources presently used by that part of a living biosphere will instead be directed to other projects.
That is the far future. Even now, however, we have the ability, the technological capacity, to eliminate more of the world's suffering than has already been tackled. All it would require is for people to make better choices. This hasn't happened because we are disorganized, because we are inhuman to one another and to animals, because evolved human nature produces harmful collective behaviors - the aforementioned war, kleptocracy, and so forth. Utopians of every stripe have had their say on how to fix these issues within the bounds of the human condition, but it seems quite clear that it cannot be done. The human mind, as presently constituted, results in behaviors and societies that will consistently sabotage the outcome of a paradise free from suffering.
Today human nature cannot be changed, but in the future we will become able to change ourselves, as well as to manufacture whatever nature we desire in the intelligences we create. Utopianism might be rescued by technology, by the ability to edit all of the fundamental aspects of human nature that we all presently take for granted. From a purely technical perspective, it seems feasible for a future society to engineer away the aspects of human nature that produce our failures. The urge to dominance, the urge to violence, the urge to cause pain and suffering and loss to others, as well as jealousy, poor impulse control, and many others. By the time that it is commonplace for organic brains to be augmented and replaced by other forms of processing machinery, I would imagine that the production of altered forms of human nature and human intelligence will be a going concern, alongside modeling and predicting the behavior of societies consisting of such modified human minds.
Unfortunately, I am skeptical that this technological capability can be successfully applied to solve the problem of human nature as it presently exists, even while it seems, from a purely technical point of view, possible to achieve the goal. Resources will always be limited at some level, whether atoms, energy, or computational power, as societies grow to match the bounds of usage. War, bad governance, and the like are the result of a race to the bottom based on violence and control of scarce resources. For so long as any section of society retains human-like nature sufficient to follow these historical patterns, then the rest will be driven to change or extinction, no matter how enlightened they are. To bypass this by changing everyone, imposing specific mental models on every living entity, would require a level of control and dictatorship that is hard to imagine coming to pass universally across the entire human polity - and that is quite beside the point that such an end is, in and of itself, just as malign as the behaviors it seeks to cure.
So: we can improve the state of lives, we can build a truly better world, but it will most likely always be flawed, marred by our own actions, just as is our world today. That is no reason to hold back, however, as there is so very much that might be improved even given that perfection is unattainable. Pain and anguish need not be our everyday companions, and need not exist throughout the animal kingdom. Suffering can be addressed, and every step we take in that direction is well worth the required effort.