Hearts & minds

Five very big books. All published by Allen Lane, the intellectual arm of Penguin, over the course of less than six months. All written by heavy-hitting North American male academics (although one is of Israeli origin and another secured the help of a journalist). And all of them developing a powerful and easily summarised central thesis that their authors contend gets to the heart of what it means to be human.

First out of the gates was legendary evolutionary biologist Robert Trivers, professor of anthropology and biological sciences at Rutgers, the State University of New Jersey, with Deceit and Self-Deception: Fooling Yourself the Better to Fool Others. To succeed in life and love, he suggests, we often have to use Machiavellian means. But when we know we are telling lies, our strenuous efforts to appear sincere often give us away. If only we can manage to deceive ourselves first, we'll be much more effective in deceiving others.

This may sound like an intriguingly odd - if rather depressing - notion, yet Trivers believes it has vast explanatory power. His book sets out to explore "evolutionary logic and deception in nature first, neurophysiology, imposed self-deception, the family, two sexes, immunology and social psychology next, then self-deception in daily life, including airplane crashes, false historical narratives, war, religion and the social sciences, before offering final thoughts on how we may fight self-deception in ourselves...The topic is universal and its many subareas carry us into every corner of human life."

Even bolder in his claims is Steven Pinker, Johnstone family professor in the department of psychology at Harvard University, in The Better Angels of Our Nature: The Decline of Violence in History and Its Causes. This examines "what may be the most important thing that has ever happened in human history", using mountains of data to argue that "violence has declined over long stretches of time, and today we may be living in the most peaceable era in our species' existence". Once we acknowledge what we have achieved and recognise we have been "doing something right", we can try to make things even better by doing more of the same, he argues.

Daniel Kahneman, emeritus professor of psychology at Princeton University and winner of the Nobel Prize for Economics, does not attempt to distil his argument into a snappy subtitle, but Thinking, Fast and Slow tackles another vast topic: the "systematic errors in the thinking of normal people".

He describes, for example, a collaborative project to produce a textbook. Once the team had been meeting for about a year, he asked them to estimate how long it would take to have a manuscript ready for delivery. The consensus was about two years. As luck would have it, however, one of the people involved was a curriculum expert who had been involved in several similar projects. When Kahneman asked him straight out how long those textbooks had taken, he went quiet, and then admitted that only 60 per cent had been completed at all - and those had taken seven to 10 years.

Now that they had a realistic forecast, they should instantly have called a halt, writes Kahneman, since "none of us was willing to invest six more years of work in a project with a 40 per cent risk of failure". So what did they do? The new information was "noted but promptly set aside" and they soldiered on regardless. The book duly took them eight years and was never used, because the government ministry that commissioned it had changed its priorities in the meantime.

This is just one vignette among many stories and experiments showing the ways that we humans systematically get things wrong. We misremember what we have experienced. We have hopelessly inaccurate intuitions about risk. We automatically create causal links between chance events. We answer the same question in different ways depending on how it is "framed". And our decisions are often influenced by totally extraneous factors (how we vote may depend on the location of the polling booth).

All in all, suggests Kahneman, people are "guided by emotion rather than by reason, easily swayed by trivial details, and inadequately sensitive to differences between low and negligibly low possibilities". Moreover, even "experts show many of the same biases as the rest of us in attenuated form".

In Beyond Human Nature: How Culture and Experience Shape Our Lives, meanwhile, Jesse Prinz, distinguished professor of philosophy at the City University of New York, takes a strongly "nurturist" position in the nature-nurture debate, arguing that "by nature, we transcend nature". Although "biology can help explain why we are more likely to flirt with a person than a potato", even an area as seemingly "natural" as sexuality is profoundly shaped by culture.

"I think the effort to figure out what comes to us naturally is a fool's errand," argues Prinz. "Human beings are not naturally monogamous, or polygamous, or anything else. We are naturally flexible [and] can adopt many different forms of social arrangement... Those who want to understand our preferences will learn more from history books than from chimpanzee troops in Gombe." He applies a similar analysis to language, emotion, morality and many other fields where researchers often claim there is "a natural way for human beings to be".

Finally, in Willpower: Rediscovering our Greatest Strength, published this week, Roy Baumeister, professor of psychology at Florida State University, and John Tierney of The New York Times argue that self-control is crucial to success in life. They examine the different forms exhibited by "living statues", "endurance artist" David Blaine and Victorian explorers such as Henry Morton Stanley (who never forgot to shave, even in a malarial swamp). They look at to-do lists and "decision fatigue", Alcoholics Anonymous and Asian "tiger mothers", not to mention the dieter's catch-22 ("In order not to eat, a dieter needs willpower. In order to have willpower, a dieter needs to eat").

Like the other writers, Baumeister and Tierney proclaim that they are on to something crucially important. There are apparently only two personal qualities that predict many "positive outcomes" in life - intelligence and self-control - and "researchers still haven't learned how to permanently increase intelligence". That means that "research into willpower and self-control is psychology's best hope for contributing to human welfare".

In all of these books, one can point to moments of stridency and showmanship, even a pleasure in polemic, which occasionally leads the authors to try to convince us that black is white. Yet all are dazzling displays of impassioned scholarship. All combine first-hand research evidence with jokes, personal anecdotes and references to popular culture in a way that manages to be entertaining as well as informative. Kahneman has described Thinking, Fast and Slow as the first of his books aimed at a mass audience, and all five publications demonstrate how well many leading academics can communicate with a broad readership when neither constrained by the research assessment exercise nor unduly plagued by self-doubt. Read one of them and it is almost impossible not to be carried away by a sense that one has now grasped some fundamental truths. The only problem is that they can't all be right.

Both Kahneman and Trivers believe we are in some fundamental sense divided against ourselves. The former notes, for example, that the "heuristics that guide citizens' beliefs and attitudes are inevitably biased" and can only be overcome by tremendous effort. Yet he seems fairly relaxed and forgiving about these flaws: "Considering how little we know, the confidence we have in our beliefs is preposterous - and it is also essential." Furthermore, his is a strikingly chaste book, which probably devotes more space to our choice of insurance policies than our choice of sexual partners.

Trivers has a much more tormented view of the world, offers woeful tales of his women troubles and seems wryly pessimistic about the chances of self-improvement: "As individuals, we can choose whether to fight our own self-deceptions or to indulge them. I choose to oppose my own - with very limited success so far." Furthermore, since he is keen to relate everything to the core evolutionary issues of survival and reproduction, he keeps returning to the battle of the sexes. He suspects that the genes we have inherited from our mothers and those that come from our fathers are at war with each other - an idea that he confesses first occurred to him "when I was trying to poison the minds of my three daughters against their mother's people". Such elaborate arguments about genes slugging it out within us are precisely the sort of thing that Prinz is determined to discredit.

Trivers' book is a million miles away from the can-do spirit of Baumeister and Tierney's, which argues that "willpower, like a muscle, becomes fatigued from overuse but can also be strengthened over the long term through exercise" (even a shot of glucose can usually help). And if they believe that individuals can dramatically improve the quality of their lives, Pinker thinks that the human race has already done so. Although evolution has implanted in us the "demons" of revenge, sadism and evil as well as the "angels" of reason, self-control and empathy, the angels have been firmly in the ascendant since the end of the Second World War, and particularly since the collapse of the Soviet Union - and he has the statistics to prove it.

It is perhaps inevitable that a big book on human nature also ends up as a kind of self-portrait, and it is not difficult to discern major differences between the authors' temperaments, values and politics.

Baumeister is a conservative in outlook, who hopes to "combine the best of modern social science with some of the practical wisdom of the Victorians". The secret of child-rearing is apparently: "Forget about self-esteem. Work on self-control."

Trivers is a born member of the awkward squad who feels that a book on deceit is as good a place as any to lash out at Nazis, Israelis and US foreign policy. With the Soviet Union no longer around to "provide a counterweight to rapacious capitalism", the post-Cold War era has "seen intense American wars, an accelerated shift of wealth to the already wealthy...and gross thievery by the wealthy and their agents leading to near economic collapse". Pinker, meanwhile, sees the same period, with its decline in violence, as one of unprecedented good fortune.

Several of these authors offer theories about why serious scholars often disagree so fundamentally (or, more cynically, why their opponents keep getting things wrong).

Kahneman suggests that "a weakness of the scholarly mind" is "theory-induced blindness: once you have accepted a theory and used it as a tool in your thinking, it is extraordinarily difficult to notice its flaws". Successful scientists require "the ability to exaggerate the importance of what he or she is doing", which can blind them to alternative perspectives. Disciplinary divisions impose further blinkers, so that economists and psychologists often seem "to be studying different species".

Trivers is far more outspoken. As he has got older, he explains, he has begun to "care less about appearing the fool, so I am willing to live with a higher ratio of foolish thought to true insight in my statements". He seems equally unconcerned about who he might offend, dismissing whole disciplines in a couple of sentences.

Pinker also thinks he knows why many people find it hard to believe his positive narrative. In much of the world, he points out, "customs such as slavery, serfdom, breaking on the wheel, disembowelling, bearbaiting, cat-burning, heretic-burning, witch-drowning, thief-hanging, public executions, the display of rotting corpses on gibbets" and so on have "passed from unexceptionable to controversial to immoral to unthinkable to not-thought-about" during what he calls the post-Enlightenment "Humanitarian Revolution". The good news is that most of us are unlikely to be hanged, drawn and quartered. But it can be hard for people to believe that humans have made any progress when they watch atrocities every night on the television and the horrors of the past are largely forgotten.

The social sciences, Trivers tells us, would benefit from "an explicit, well-tested (biological) theory of self-interest" - which is why we find only "a few honest historians". Economics is not a true science, although it "acts like a science and quacks like one", since its vague notion of "utility" is not rooted in biology. Most psychology consists of "competing guesses about what [is] important in human development, none with any foundation".

But more interesting than this disciplinary one-upmanship is the general point that Trivers makes about human arguments. They "feel so effortless because by the time the arguing starts, the work has already been done. The argument may appear to burst forth spontaneously, with little or no preview, yet as it rolls along, two whole landscapes of information lie already organised, waiting only for the lightning of anger to reveal them."

Reading all these books gives one the exhilarating and disorienting sense of visiting five different intellectual landscapes. All are fascinating, although everyone will find some more familiar and congenial than others. But where do they give an accurate picture of the world and where are they distorted by disciplinary tunnel vision or by their authors' prejudices?

Perhaps someone will eventually produce an even bigger book, offering an aerial view of all the separate mountain plains. Until then, we might as well enjoy the scenery.