It will be pointless to pretend this is an ordinary review. Despite its unlovely title and rigorous approach, Valeria Ugazio's book has, in one form or another – in Italy it went through many versions before its long overdue publication in English – been a favourite of mine for almost a decade. So forget the latest novel, the summer travel book, and just concentrate all your reading energies on this. Even if you don't agree with it, I can guarantee this book will offer you a different, intriguing, possibly liberating way of thinking about everyone you know, every family – above all your own family, yourself.

Some context. Some weeks ago the British Psychological Society finally found the courage to signal their disquiet with psychiatry's predominantly biomedical model of mental distress, the notion that being mentally ill, whether depressed, obsessive, phobic, anorexic or schizophrenic, is essentially a biological issue, to be treated with a range of expensively promoted pharmaceutical products.

The problem for those who suspect that this model is crude, drastic or just plain wrong, is to offer a convincing alternative. Dr Lucy Johnstone, who was involved in the Psychological Society's recent statement of concern, remarked in an interview that there is "overwhelming evidence that people break down as a result of a complex mix of social and psychological circumstances – bereavement and loss, poverty and discrimination, trauma and abuse". This is extremely vague. With 30 years of experience as a therapist and professor of psychology, Ugazio's life-long work has been to put some order into that "complex mix".

Semantic Polarities opens with four case studies, four crises – an 11-year-old girl devastated by a first obsessive-compulsive attack, a successful young man paralysed by panic, a teenager relapsing into anorexia, and a single mother falling into depression and abandoning her four-year-old son. In each case Ugazio sketches in the social and family context and asks the million-dollar question: why? Why this particular individual, why this particular pathology, why this precise moment? If it is not a biomedical problem, what is it?

Ugazio is not so presumptuous as to imagine she has given a complete answer to those questions, but moving back and forth between case study and reflection, drawing on a wide range of thinkers in psychology, anthropology, sociology and philosophy, she slowly puts together a model that does indeed make sense of these people's stories, placing each condition in meaningful relation to the particular life context in which it occurs. In fact, Ugazio's main point is that these four mental illnesses can only occur within four distinct worlds of meaning: hence the "semantic" in Semantic Polarities. Put very crudely, we are talking about people who cannot choose between altruism and selfishness, dependence and independence, winning and losing, belonging and not belonging.

This territory is a minefield. Aside from the enthusiasm of the pharmaceutical companies, one of the reasons why the biomedical model for mental illness has prevailed is that it exonerates everyone from responsibility or even involvement in the patient's problem; this is just another sickness. On the other hand, the moment we start talking about environmental factors – dominant mothers, achievement-obsessed fathers, child abuse, poverty – the issue of blame comes in and the debate grows shrill. Ugazio is not interested in pointing fingers; as she sees it mental illness cannot be explained by simple equations of cause and effect. What she talks about is how, over the years and always in relation with others, a personality can be structured in such a way that it is eventually trapped in some insoluble and painful dilemma. "Permitted and forbidden stories" is the book's subtitle: our upbringing makes some roads desirable, others unacceptable. In the many case histories she examines, the trigger for mental illness comes when what is absolutely unacceptable is simultaneously understood as absolutely necessary.

The idea is sophisticated, meticulously documented and carefully nuanced; any brief explanation will be simplistic. But let's start with the ongoing family conversation that surrounds all of us as we come to consciousness and our personalities are formed. When people are assessed in a family or any tightly knit group, various criteria will be present; people are judged as winners or losers, good or bad, courageous or fearful, and so on. Criteria such as these tend to sort themselves into hierarchies and, depending on the family and its history, one polarity will dominate over others when it comes to establishing a person's value. An example: in Italy Berlusconi is widely believed to be corrupt, but for many people the fact that he is a successful man, a winner, is more important, so they vote for him anyway; the semantics of power, as Ugazio calls it, is for such people stronger than the semantics of good and evil.

Imagine a family where the main values are courage, independence, freedom. Growing up, a child hears people described in these terms. The world is dangerous, otherwise courage wouldn't be important; some people are able to face it alone; others are more needy; they need home, protection, affection, a steady job. These things are not at all bad; quite the contrary, but in this family they are perceived as limiting, hardly heroic. The values are not notional but embodied by all the people who surround the child: the aunt who became a globetrotting musician, the father who won't take a plane and becomes anxious in lifts. Roles polarise. One form of behaviour invites its opposite, or competition. Ugazio writes: "As a result of these conversational processes, members of these families will feel, or be defined as, fearful or cautious or, alternatively, courageous, even reckless. They will find people prepared to protect them, or alternatively people who are unable to survive without their protection. They will marry people who are fragile or dependent, but also individuals who are free and sometimes unwilling to make commitments. They will suffer for their dependence. They will try in every way to gain their independence. In other cases they will be proud of their independence and freedom, which they will defend more than everything else. Admiration, contempt, conflict, alliances, love and hatred will be played out around issues of freedom/dependence."

Ugazio refers to this family dynamic as a "semantics of freedom". Sooner or later the growing child will have to decide where he or she stands within it: am I the explorer or the stay-at-home, or some carefully concocted mix of the two; perhaps intellectually an explorer, but physically a stay-at-home? And what happens if you can't find a position you're comfortable with, or if something happens to throw the position you've taken into crisis?

Imagine: an entrepreneur father, taking risky decisions, handling good times and bad, his own man; a mother, hugely admiring of her husband, but herself happy at home, happy to be dependent. A first daughter models herself on father, travels, finds and fires boyfriends, studies abroad. A second child, a boy, again models himself on Dad, gets into extreme sports, has a steady girlfriend but constantly puts off marriage. The third child perhaps keeps mother closer, begins to distinguish himself from the others because of his privileged relation with her, is happy at home. But in adolescence this third child appreciates that actually mother's admiration is not for people like himself, but for those like father, who is always absent, taking risks. She loves her youngest boy, but is more impressed by his independent siblings.

The boy starts to look for a way of expressing independence. He sets off on an Erasmus exchange in France, but now fears losing the identity and protection that the privileged relationship with mother gave. Coming home early, he worries that, however reassuring, the relationship with mother is limiting, castrating. Later this ambivalence about affection in relationships is transposed to a girlfriend. A relationship brings safety, but it is experienced as humiliating. Where does he really stand on these matters? Now it only needs a couple of major life events, perhaps the need to make some identity-defining decision, and this dilemma could become unbearable. We hear of a young man who has panic attacks every time he leaves his home and his mother, and vomits constantly when he returns. It is not that Ugazio is saying that every person in such situations will develop phobic symptoms; simply that her long experience as a therapist suggests that where you have phobic disorders you have a sufferer who has grown up in a world dominated by these values. The stories she offers are at once extremely varied and yet essentially consistent with this pattern.

Ugazio looks at three other "semantics" and their related psychopathologies. The semantics of good and evil, or altruism and self-indulgence, which lies behind obsessive compulsive disorders; the semantics of power, of winning and losing, in which she includes eating disorders; and then a semantics of belonging, families whose main concern is their inclusion or exclusion from this or that group or relationship, a concern she identifies as the terrain of the depressive. Again, it's not that other criteria don't exist when these families talk together, just that one cluster of values dominates. Alas, in each case there is danger that the play of relationships and meaning in the family will trap someone in a position where they feel the need to be at opposite poles of the semantic at the same time: they need to be good, to please the parent they are closest to, but if they don't indulge in some pleasure this parent doesn't approve of, they feel they are simply not living. Or they need to compete with a parent but cannot accept the loss of closeness that competition would bring. They have to be in the group, but feel the group is not worthy of them; to be in it is to be demeaned, to be out of it is to be lost.

But if Semantic Polarities has a strong underlying scheme, it is never merely schematic. Ugazio makes us feel how immensely complex the structuring of each individual personality is, how many factors are involved, how many opportunities, pitfalls, traps. Above all, she has created a model of mental illness, and mental health, which includes us all; the disorder is in intimate relation with the context in which it developed, but without assuming that anyone is "to blame". Indeed Ugazio's point is that we are all constantly finding strategies that allow us to reconcile competing values. In this sense she makes us acutely aware of our kinship with sufferers of mental illness: we are all part of the same family.

• Tim Parks's Italian Ways is published by Harvill Secker