Over the last decade, it has become common to complain that governments, particularly in the west, have been too narrowly focused on the pursuit of rising GDP at the expense of other social goods. People have looked wistfully to Bhutan, where, since 1972, official government policy has been to prioritise instead the "Gross National Happiness".

Be careful what you wish for, you might just get it. For now that both government and opposition have embraced the happiness agenda, sceptical voices are warning that this marks a disturbing intrusion of the state into the private lives of citizens, and that, far from being benign, attempts to regulate the subjective states of citizens could have sinister implications. Well-being, once absent from political discourse, has become a contested issue at the very heart of it.

Over recent weeks alone, policy proposals that put well-being and happiness at their core have been ubiquitous. Demos published a report, "Building Character", which proposed "a range of policy interventions", arguing character capabilities "ought to be a concern for policy-makers".

The Young Foundation also published "Sinking and Swimming", arguing that "there is no reason why regular GDP reports should not be accompanied by regular reports on the psychological fitness and health of the population". The time may be right, it said, to rethink welfare through the lens of mental health, rather than material prosperity and physical well-being.

Such ways of thinking are now firmly entrenched in Westminster and Whitehall. On 7 December, the Government published a report, "New Horizons", setting out its 10-year mental health strategy. As Gordon Brown said in its introduction: "This is about more than preventing mental illness ... it is also about helping individuals and communities to bring the best out of themselves."

As psychological well-being becomes more than just a health service concern that deals with chronic or acute problems, all branches of the state start to take an interest in it. So, for instance, the recent announcement that mental health workers are to be placed in all job centres came not just from the Department of Health, but also the Department for Work and Pensions.

Well-being has also found its way on to the timetable at a top public school, Wellington College, where it was initially met with bewilderment but has increasingly received acclaim. Since the Master of Wellington, Anthony Seldon, is a senior education advisor to the Conservative Party, expansion of the lessons into state schools is no longer an unlikely prospect.

The driving force behind this sea-change in Government priorities is the "new science of happiness", positive psychology, enthusiastically championed in the UK by the government's "happiness tsar", the psychologist Lord Richard Layard. The core tenets of positive psychology have become so absorbed by the Government that they can be summed up in the vision statement of "New Horizons", which seeks "to move towards a society where people understand that their mental well-being is as important as their physical health if they are to live their lives to the full".

But although the report says that we now know "the factors that affect well-being and some everyday strategies for preserving and boosting it", both the claims of positive psychology and the role of the state in promoting individual well-being are hotly contested. Providing the most sustained and visible resistance is Frank Furedi, Professor of Sociology at the University of Kent and the leading intellectual force behind of the Institute of Ideas. Furedi set out his stall in his book Therapy Culture, a phrase which is not about therapy as such, but the trend towards the pathologising of ordinary problems of living. In a therapy culture, people increasingly treat personal difficulties as disorders which need to be treated by professionals. Since well-being has become an explicit objective of Government policy, the political dimensions of such objections have become more apparent.

For instance, Dennis Hayes, Professor of Education at the University of Derby and co-author of The Dangerous Rise of Therapeutic Education, is alarmed by the extent to which ideas like "happy workers are more productive workers" are becoming management mantras. Hayes has argued that he'd rather people were miserably unemployed and plotting revenge than happily engaged in trivial work. Therapy culture, he believes, is filling a vacuum where politics used to be. "Traditionally you'd say disgruntlement led to the desire for change," he told me. "Disgruntlement now leads to therapy."

Such worries could be dismissed as unreconstructed, a priori Marxism. According to Marx, employees are alienated from their labour, as they do not own and profit from its products. Any employee who professes to be happy is therefore suffering from false consciousness. The promise of positive psychology thus becomes a threat: to make a more content workforce is to blind it to its sorry state.

But even if you don't go along with this classical Marxist analysis, isn't it reasonable to worry about the state using therapeutic tools to make more productive workers? You don't need to posit a paranoid conspiracy theory to see that the Government is at least in part enthused by the well-being agenda on the basis of its economic impact. "New Horizons" estimates that the full cost to the economy of mental illness is "around £77bn, mostly due to lost productivity".

Certainly, the Government has made very strong links between being mentally well and having a job. "One of the best ways to improve mental health is through work," wrote Gordon Brown. "We know that work is good for people and that's why we want to give everyone the support they need to stay in a job, or get back to work," agreed Yvette Cooper, the Health Minister. If we "know" these things, then don't we also "know" that anyone who is not happily in work has something wrong with them?

There are other ways in which advocates of positive psychology explicitly make claims that it helps with social goals that governments might have. Anthony Seldon, for instance, has said that he believes that the introduction of well-being classes has probably contributed to better exam grades at Wellington College. Martin Seligman, the godfather of positive psychology, talks about happiness making us "good citizens".

The fear is of a Brave New World, regulated not by the popping of soma pills but by the more indirect route of positive psychology interventions. The result will be content, compliant citizens, students and employees who come to see problems as only being ones of responses to circumstances, not in potentially unjust circumstances themselves.

Behind some of these critiques is a misguided belief that the battle between the interests of state and citizens is a zero-sum game, when it could actually be a win-win. The happiness of workers need not be phoney just because it also means they're more productive, just as children might leave school both more resilient and content as well as with grades that schools and education ministers are proud of. If there is a problem with the politics of well-being, it cannot simply be that the state has something to gain from it.

There are, however, plenty of more serious questions raised by the growth of the well-being agenda, which largely assumes a medical model. "Mental health problems are common," says "New Horizons". "They are illnesses with causes and treatments, like physical illnesses." Even if that is the correct way to think about some problems, whether this is the right paradigm for most of what concerns our mental and emotional well-being is far more contentious.

Whether we view a difficulty as a problem of living or clinical conditions with treatments completely changes how we think about and deal with the issues we face. Consider how a lack of motivation to do a boring job could be seen as a sane response to intolerable external circumstances, or as a symptom of a kind of depression. If the latter becomes the orthodoxy, then the disgruntlement of workers will increasingly be assumed to be a sign that they, not the workplace, is dysfunctional.

For example, Martin Seligman recently talked on Radio 4's All In The Mind about a waitress who hated her job. Seligman got her to take a test which identified her "signature strengths", the strongest of which was "social intelligence". "So her job," he said, "was to recraft waitressing to use social intelligence more." That meant resolving to "make the encounter with her the social highlight of every customer's evening." This made her happier, less depressed and got her bigger tips. Good for her, you might think. But what are the wider consequences of adopting this kind of approach? The "job" of everyone who is not happy with their work is simply to "recraft" it so that they are. So if you're not happy with your job, you're just not doing your job.

This connects with the broader concern that happiness is becoming not something you are free to strive for, but an obligation. "There is no duty we so much underrate as the duty to be happy," wrote Robert Louis Stevenson, a quotation that was used as the epigraph of a recent self-help book and which seems to be increasingly repeated. If happiness is something we can learn and is under our control, then the unhappy are not merely unfortunate, they're negligent.

The objections against positive psychology would carry little force, however, if its main factual claims were simply true, and the evidence that they are can seem very impressive. Graphs and charts can be wheeled out to show that people who are more optimistic and resilient do better on all number of measures of life success, such as health, happiness, wealth and longevity. And optimism and resilience are things which it is claimed can be taught. The upshot is that we can and should learn to be more positive.

The problem, however, is that by its own admission positive psychology is a young discipline, and there often seems to be a lack of subtlety in its interpretation of data. Think, for example, about what nutritional science might tell us, if it based its findings on survey data. It would find that people who eat more fruit and vegetables than meat every day are healthier than those who don't. True, but what prescription follows? Not that everyone should eat as much fruit and veg as possible and avoid all meat. The evidence tells us eating plants is important, but it doesn't tell us what a balanced diet looks like.

There is a similar danger that psychologists who divide the world up into positive and negative thinkers and find that the positive-minded do better are too quick to conclude that therefore we should all strive to be more positive. As yet, there is little work being done which considers the roles of both positivity and negativity in a balanced psychological diet. That which does presents a much more complicated picture. For instance, there is considerable evidence, gathered by the psychologist Julie Norem and others, that defensive pessimism – believing that things will probably go wrong – has many psychological benefits, such as building resilience.

Such findings challenge one of the central tenets of positive psychology, that we should all try to be more optimistic. "To claim optimism as a virtue without any reference to context is, I think, vacuous, inappropriate, and misleading," says Norem. "Also, optimism tends to go hand in hand with overconfidence, and often with egocentrism, where you feel okay about yourself, but maybe you feel more okay about yourself than you should."

The possibility that perhaps there are times when we shouldn't feel good is often one that is glossed over when positive psychology is discussed as though it were a value-free science. In fact it is thickly value-laden, in ways which are often concealed in its language, such as the phrase "emotional well-being", which John Cottingham, the Professor of Philosophy at Reading university, thinks is "a kind of awkward fudge".

Well-being, he argues, is a basic ethical concept to do with the pursuit of the good human life. "If you just shove 'emotional' in front of that, you seem to be thinking, we don't have to go into all that ethical and philosophical guff about virtue. We can just look at the emotions, which are something psychological and emotional, and we can measure those and get 'improved outcomes'."

But although this may be the popular conception of positive psychology, its leading advocates make no secret that it is much more than neutral science. "Of course it's not value free," Layard told me. "It is based on the assumption that misery is bad and happiness good. And it assumes that everybody's happiness/misery matters equally, which is the central principle of social justice." Indeed, Layard devotes a chapter of his book Happiness to a defence of utilitarianism, the view that what is right is to increase the greatest happiness of the greatest number. "Bully for Bentham," is his conclusion.

Anthony Seldon also proudly says that positive psychology "is value-full, and the values are profoundly humane", based as they are upon "harmony in relationships, with oneself, with the environment and with others".

But if the well-being agenda is indeed so value-laden, does the state have any business in promoting it? "The leaders of society have always been concerned with the development of character," argues Layard, "since no society can function without some shared habits and norms. And they have always felt special responsibility for children and young people."

This echoes the challenge to mainstream liberal thought by communitarians, led by last year's Reith lecturer, Michael Sandel. For too long, liberals have kidded themselves that the civic sphere is a value-neutral zone, where decisions are made without any substantive vision of the good life. But any political programme implies a value system, and Layard argues that at least positive psychology's is "less judgmental than many value systems, since it considers lasting happiness to be a value wherever it comes from".

In the wider public and political imagination, however, positive psychology is too often seen as just a set of empirical facts. "Scientists have discovered" is the usual prefix to any claim made about positive psychology. But claims about what is are so often followed up by claims about what we should do. Evidence that children of married couples do better than those of cohabiting and single parents (which is in any case too simplistic a conclusion to draw from the statistics), for instance, is used as grounds for promoting marriage. But by the same logic, why not argue that people should be encouraged to become religious – in any religion – because faith is also correlated with happiness? Philosophers have warned for centuries about the dangers of sliding from "is" to "ought" without sufficient justification, but in their enthusiasm for the encouraging claims of positive psychology, not enough people are showing the same caution now.

Despite all these reasons to be wary about the well-being agenda and its encampment at the high table of politics, there is always a danger of throwing out the baby with the bathwater. It would simply fly in the face of the evidence to suggest there is nothing of substance or interest to have emerged from the research into positive psychology. And if we do want government to be concerned with more than just economic growth, it would be foolish for it to ignore the lessons it may have to offer.

Nevertheless, there are serious questions to be asked about the haste with which government, educators, business and think tanks have embraced positive psychology. This is not just objective, value-free science, but a hybrid of often-incomplete empirical evidence and prescriptions for the good life which haven't always been thought through. Positive psychology is too serious and important to be just dismissed, but before it is accorded too much respect, it needs to grow up and be explicit about where it values really lie. Our genuine well-being may well depend on that.

The happiness test: By Professor Ed Diener, psychologist at University of Illinois

How can you tell you are happy? Below are five statements that you may agree or disagree with. Using the 1-7 scale below, indicate your agreement with each item by placing the appropriate number on the line preceding that item. Please be open and honest in your responses

7 Strongly agree

6 Agree

5 Slightly agree

4 Neither agree nor disagree

3 Slightly disagree

2 Disagree

1 Strongly disagree

In most ways my life is close to my ideal.

The conditions of my life are excellent.

I am satisfied with my life.

So far I have the important things I want in life.

If I could live my life over, I would change almost nothing.

31-35 Extremely satisfied

26-30 Satisfied

21-25 Slightly satisfied

20 Neutral

15-19 Slightly dissatisfied

10-14 Dissatisfied

5-9 Extremely dissatisfied

Understanding Scores on the Satisfaction with Life Scale

30-35 Highly Satisfied

Respondents who score in this range love their lives and feel that things are going very well. Their lives are not perfect, but they feel that things are about as good as lives get. Furthermore, just because the person is satisfied does not mean she or he is complacent. In fact, growth and challenge might be part of the reason the respondent is satisfied. For most people in this high-scoring range, life is enjoyable, and the major domains of life are going well – work or school, family, friends, leisure, and personal development.

25- 29 Satisfied

Individuals who score in this range like their lives and feel that things are going well. Of course their lives are not perfect, but they feel that things are mostly good. Furthermore, just because the person is satisfied does not mean she or he is complacent. In fact, growth and challenge might be part of the reason the respondent is satisfied. For most people in this high-scoring range, life is enjoyable, and the major domains of life are going well – work or school, family, friends, leisure, and personal development. The person may draw motivation from the areas of dissatisfaction.

20-24 Average satisfaction

The average of life satisfaction in economically developed nations is in this range – the majority of people are generally satisfied, but have some areas where they very much would like some improvement. Some individuals score in this range because they are mostly satisfied with most areas of their lives but see the need for some improvement in each area. Other respondents score in this range because they are satisfied with most domains of their lives, but have one or two areas where they would like to see large improvements. A person scoring in this range is normal in that they have areas of their lives that need improvement. However, an individual in this range would usually like to move to a higher level by making some life changes.

15-19 Slightly below average in life satisfaction

People who score in this range usually have small but significant problems in several areas of their lives, or have many areas that are doing fine but one area that represents a substantial problem for them. If a person has moved temporarily into this level of life satisfaction from a higher level because of some recent event, things will usually improve over time and satisfaction will generally move back up. On the other hand, if a person is chronically slightly dissatisfied with many areas of life, some changes might be in order. Sometimes the person is simply expecting too much, and sometimes life changes are needed. Thus, although temporary dissatisfaction is common and normal, a chronic level of dissatisfaction across a number of areas of life calls for reflection. Some people can gain motivation from a small level of dissatisfaction, but often dissatisfaction across a number of life domains is a distraction, and unpleasant as well.

10-14 Dissatisfied

People who score in this range are substantially dissatisfied with their lives. People in this range may have a number of domains that are not going well, or one or two domains that are going very badly. If life dissatisfaction is a response to a recent event such as bereavement, divorce, or a significant problem at work, the person will probably return over time to his or her former level of higher satisfaction. However, if low levels of life satisfaction have been chronic for the person, some changes are in order – both in attitudes and patterns of thinking, and probably in life activities as well. Low levels of life satisfaction in this range, if they persist, can indicate that things are going badly and life alterations are needed. Furthermore, a person with low life satisfaction in this range is sometimes not functioning well because their unhappiness serves as a distraction. Talking to a friend, member of the clergy, counsellor, or other specialist can often help the person get moving in the right direction, although positive change will be up to the person.

5-9 Extremely dissatisfied

Individuals who score in this range are usually extremely unhappy with their current life. In some cases this is in reaction to some recent bad event such as widowhood or unemployment. In other cases, it is a response to a chronic problem such as alcoholism or addiction. In yet other cases the extreme dissatisfaction is a reaction due to something bad in life such as recently having lost a loved one. However, dissatisfaction at this level is often due to dissatisfaction in multiple areas of life. Whatever the reason for the low level of life satisfaction, it may be that the help of others are needed – a friend or family member, counselling with a member of the clergy, or help from a psychologist or other counsellor. If the dissatisfaction is chronic, the person needs to change, and often others can help.

Common to each category:

To understand life satisfaction scores, it is helpful to understand some of the components that go into most people's experience of satisfaction. One of the most important influences on happiness is social relationships. People who score high on life satisfaction tend to have close and supportive family and friends, whereas those who do not have close friends and family are more likely to be dissatisfied. Of course the loss of a close friend or family member can cause dissatisfaction with life, and it may take quite a time for the person to bounce back from the loss.

Another factor that influences the life satisfaction of most people is work or school, or performance in an important role such as homemaker or grandparent. When the person enjoys his or her work, whether it is paid or unpaid work, and feels that it is meaningful and important, this contributes to life satisfaction. When work is going poorly because of bad circumstances or a poor fit with the person's strengths, this can lower life satisfaction. When a person has important goals, and is failing to make adequate progress toward them, this too can lead to life dissatisfaction.

A third factor that influences the life satisfaction of most people is personal – satisfaction with the self, religious or spiritual life, learning and growth, and leisure. For many people these are sources of satisfaction. However, when these sources of personal worth are frustrated, they can be powerful sources of dissatisfaction. Of course there are additional sources of satisfaction and dissatisfaction – some that are common to most people such as health, and others that are unique to each individual. Most people know the factors that lead to their satisfaction or dissatisfaction, although a person's temperament – a general tendency to be happy or unhappy – can colour their responses.

There is no one key to life satisfaction, but rather a recipe that includes a number of ingredients. With time and persistent work, people's life satisfaction usually goes up when they are dissatisfied. People who have had a loss recover over time. People who have a dissatisfying relationship or work often make changes over time that will increase their dissatisfaction. One key ingredient to happiness, as mentioned above, is social relationships, and another key ingredient is to have important goals that derive from one's values, and to make progress toward those goals. For many people it is important to feel a connection to something larger than oneself. When a person tends to be chronically dissatisfied, they should look within themselves and ask whether they need to develop more positive attitudes to life and the world.