Ethics is a human invention. It sprung not from the will of a divine commander, nor coalesced from pure reason, but was a cultural technology concocted by our distant ancestors to solve the problems inherent in social living.

But somewhere between its invention and today, ethics has become warped. We allowed the original function of ethics to be forgotten. Instead we took the presumed commands of a divine will or the abstract strictures of pure reason to be the roots of ethics, and constructed distorted moral systems in their spirit, forgetting the core purpose of ethics.

Today, we ought to return to the fundamental questions of how to solve the problems of social living, including problems both familiar and remote to our ancestors. We ought to propose new solutions that directly address these problems, that are unburdened by fallacious justificatory frameworks or the maladapted moralities of our distant past.

If there is one overriding message from Philip Kitcher's latest book, The Ethical Project , it is this: ethics is a worldly topic, and it requires worldly solutions created by us.

This is not necessarily a new idea - there is a long history of thinkers who have suggested that morality is a tool created, not given or discovered - but it is an idea that is in desperate need of revival.

This is particularly so in light of the profound advances made in the empirical sciences over the past decade or so, which have painted a far more detailed picture of how humans have evolved biologically, psychologically and culturally.

We can now tell a plausible (if not complete and verifiable) story, as Kitcher does, of how we transformed from a primate not dissimilar to modern day chimpanzees into the ultra-social species that has taken over the world using the power of cooperation on an unprecedented scale.

We now know well the tremendous benefits of social living and cooperation, and the problems of free-riding and social disruption that can drag us down to a war of all against all. And we can see how evolution endowed us with a slew of faculties that encourage cooperation, from "moral" emotions like empathy and guilt, to a psychology predisposed to creating and conforming with norms (just watch children in the playground to see this in action) and a propensity to punish those who break those norms.

But these psychological faculties that promote psychological altruism - the genuine desire to promote someone else's interests even at the cost of one's own - have their limits. Evolutionary models, along with everyday experience, show that self-interest can never be entirely eradicated. And in social ventures, there are often opportunities to exploit someone else's altruistic tendencies for self-interested advantage.

Which is why we invented ethics.

Kitcher paints a somewhat idealised, but not implausible, picture of our distant ancestors sitting around the campfire in the "cool hour" discussing the frictions and "altruism failures" of the day. Then they would discuss how best to deal with them.

They would concoct new rules of behaviour. Norms to be followed. Issue punishment against defectors. Praise the conformers. The practices and traditions of the culture itself would shift and evolve to entrench these norms. It was a process of cultural innovation, including experimentation and revision, tested against the cooperative successes or failures of neighbouring groups.

However, lacking the current tools at our disposal to analyse the complex dynamics of social life - such as the convolutions of game theory, which was only invented in the mid-twentieth century - our ancestors responded merely to the symptoms of social unrest. And they proposed solutions ignorant of the deeper causes, the "problem background." As such, sometimes they innovated rules that solved one problem and created several new ones.

One such innovation emerged to solve the problem of encouraging conformity with the moral code, particularly when individuals weren't being actively scrutinised by their peers. In such situations there would surely be temptation to give in to self-interest and flout the code.

The notion of an "unseen enforcer," as Kitcher puts it, an all-seeing moral authority from which - or from whom - no transgression goes unnoticed, would have helped encourage conformity on pain of punishment in this life or next.

This unseen enforcer likely tapped into our already strong propensity to animate the world around us with agency, spirits and divinity. Our ancestors surely genuinely believed in the existence of the unseen enforcer, despite the fact it happened to be a convenient fiction.

Thus was religious morality born. The mistake was to see the divine as the source of morality, rather than a fiction to encourage conformity and to spread cultural and moral norms (not that there was a distinction back then). One problem solved, several more problems created.

One problem was that new moral norms came to spring from the presumed will of the divine authority, or interpretations of sacred texts, rather than in response to the actual problems of social living. Many of these solutions may have actually harmed the original moral cause, as we can observe today with religiously-motivated prohibitions on contraception that cause untold suffering and harm. Other norms emerged purely to entrench the religious system itself, rather than benefit its adherents.

The second problem is that religion can easily facilitate the creation of an elite class that administers the moral norms. As is human nature, power tends to corrupt. This leads to a manipulation of the norms, either intentionally or unintentionally, that tend to favour the elite at the expense of the masses.

But then, if morality isn't founded on some external immutable source, if it's built by humans for humans, how can we account for the notion of ethical progress? It seems readily apparent to us today that the abolition of slavery, the move away from harsh eye-for-an-eye retributionist punishment and the elevation of women's rights are clear examples of ethical progress rather than examples of "mere change."

But on what grounds can we claim progress? If, as Kitcher argues, there is no divine commander, and if there is no special class of objective moral facts to be discovered, we need to find some other fulcrum about which the ethical world pivots. This is a central issue of Kitcher's book.

Kitcher's response is that the fulcrum is the original function of morality: to solve the problems of social living caused by the limits and failures of our natural altruism.

The innovations that inspired the abolition of slavery and eye-for-an-eye retributionism, and for the expansion of women's rights, are examples of new ethical solutions to problems of social living, resulting in systems that facilitate more cooperation and less harm and social conflict. Like any ethical innovations, they might not be without their own disruptive consequences, but on the whole they advanced the cause of cooperative social living more than they harmed it. Thus: ethical progress.

So ethical progress is possible. All we need to do is work to gain a deeper understanding of the "problem background" of facilitating social living given our unique circumstances today and propose new innovations and solutions to these problems. This is the core of Kitcher's method, called pragmatic naturalism - "pragmatic" because it grounds itself in the real world, drawing on the philosophical method of the American pragmatists John Dewey and William James; "naturalism" because it posits no non-natural or supernatural entities to justify ethics.

But here's the rub. There is no single answer to the manifold problems of social living. Different groups will have different social dynamics. They'll have different environmental conditions, different distributions of resources, different problems to solve. After all, the problems inherent in the distribution of scarce resources are quite different from the problems of how to fairly distribute a surplus of resources.

Different groups and individuals will have differing visions of the "good life" they seek to live - although not all "good lives" are created equal, and the range of possible "good lives" is ultimately bound by our nature.

The result is pluralism. Not a bald relativism, which allows an anything goes mentality - for that would entirely disruptive to the pursuit of social living - but an acknowledgement of different ways of genuinely living well. And a like acknowledgement that these ways can come into conflict that needs to be resolved through more ethical deliberation.

Kitcher encourages us to embrace what he calls "dynamic consequentialism," which supposes that

"conceptions of the good evolve, that some of the transitions among those conceptions are progressive ... and that later conceptions of the good are (sometimes) superior to their predecessors, even though none can claim to be the last word."

He ends by making some suggestions in the spirit of "philosophical midwifery," proposing new ideas to enter into the ethical narrative he seeks to promote. He treats issues such as population limits and sustainability, the management of scarce resources and encouraging and maintaining equality. These normative suggestions are noteworthy, and offer an example of Kitcher's pragmatic naturalism in action, but it is the first part of the book and the method itself that is of most import.

The Ethical Project might not be the most engaging read, it might lack the grand sweep and rhetorical flourish of more popular philosophy and science writers, but it is a book that ought to have a significant impact on ethics and ethical discourse. And about time too.

The key message - that ethics is a human invention, and that it falls to us to figure out how to structure our lives and societies - is a welcome one. It presents itself as a compelling alternative to the dogmatic strictures of religious morality. It departs from the rarefied realm of contemporary philosophical ethics that is so detached from issues touching the real world. It charts a middle, pragmatic pluralist, road between untenable absolutism and unfettered relativism. And it is rare in its embracing of the other humanities and sciences, including evolutionary biology, psychology, sociology, anthropology and history.

If humanity is to face the profound challenges of life in the twenty first century and beyond - a life radically different from that in which most religious moralities were formed - we need to embrace a sophisticated philosophical method that will enable us to understand and respond to the problems of social living directly and figure out a way to engage in fruitful ethical discourse and debate.

Kitcher's pragmatic naturalism represents a bold and significant advance to this end, and one that ought to have a deep impact on contemporary ethics.

Tim Dean is a philosopher and science journalist. He's completing a PhD in philosophy at the University of New South Wales exploring how evolution has shaped our moral psychology to respond to the diverse challenges of social living, and how that psychology influences ethical discourse today.