We are still in early stages of developing scientific answers to these questions. But they are fundamentally scientific. Note also that like culinary tastes there may not be unique answers to these questions, but sure it does not mean that all diets are equally good for your health.

Human well-being entirely depends on events in the world and on states of the human brain. Consequently, there must be scientific truths to be known about it. A more detailed understanding of these truths will force us to draw clear distinctions between different ways of living in society with one another, judging some to be better or worse, more or less true to the facts, and more or less ethical. Clearly, such insights could help us to improve the quality of human life.

We may not be able to resolve every moral controversy through science. Differences of opinion will remain. But opinions will be increasingly constrained by facts. And it is important to realize that our inability to answer a question says nothing about whether the question itself has an answer. Exactly how many people were bitten by mosquitoes in the last sixty seconds? How many of these people will contract malaria? How many will die as a result? Given the technical challenges involved, no team of scientists could possibly respond to such questions. And yet we know that they admit of simple numerical answers. Does our inability to gather the relevant data oblige us to respect all opinions equally? Of course not. In the same way, the fact that we may not be able to resolve specific moral dilemmas does not suggest that all competing responses to them are equally valid. Mistaking no answers in practice for no answers in principle is a great source of confusion.

People who want to argue moral questions are not scientific are in effect saying reason is powerless to answer the most important questions in human life. And how a person perceives the gulf between facts and values seems to influence their views on almost every issue of social importance— from the fighting of wars to the education of children.

This rupture in our thinking has different consequences at each end of the spectrum: religious conservatives tend to believe that there are right answers to questions of meaning and morality, but only because the God of Abraham deems it so. They concede that ordinary facts can be discovered through rational inquiry, but they believe that values must come from a voice in a whirlwind. Scriptural literalism, intolerance of diversity, mistrust of science, disregard for the real causes of human and animal suffering, this is how the division between facts and values expresses itself on the religious right.

From the point of view of popular culture, science often seems like little more than a hatchery for technology. While most educated people will concede that the scientific method has delivered centuries of fresh embarrassment to religion on matters of fact, it is now an article of almost unquestioned certainty, both inside and outside scientific circles, that science has nothing to say about what constitutes a good life. Religious thinkers in all faiths, and on both ends of the political spectrum, are united on precisely this point; the defense one most often hears for belief in God is not that there is compelling evidence for his existence, but that faith in him is the only reliable source of meaning and moral guidance. Mutually incompatible religious traditions now take refuge behind the same non sequitur.

It seems inevitable, however, that science will gradually encompass life’s deepest questions—and this is guaranteed to provoke a backlash. How we respond to the resulting collision of worldviews will influence the progress of science, of course, but it may also determine whether we succeed in building a global civilization based on shared values. The question of how human beings should live in the twenty-first century has many competing answers—and most of them are surely wrong. Only a rational understanding of human well-being will allow billions of us to coexist peacefully, converging on the same social, political, economic, and environmental goals. A science of human flourishing may seem a long way off, but to achieve it, we must first acknowledge that the intellectual terrain actually exists.