Psychiatry is not the science of unhappiness. It was never meant to be. Yet in recent decades the boundaries of the discipline have expanded so widely that almost any form of distress seems eligible for medical attention. In societies preoccupied with well-being, psychiatry faces the temptation to annex unhappiness itself as a diagnostic domain. If we yield to that temptation, we risk losing sight of what defines our profession: the care of people whose suffering is rooted in illness, not in the ordinary trials of human existence.

The modern history of psychiatry can be read as a search for equilibrium between its scientific and humanistic dimensions. Karl Jaspers described psychiatry’s dual nature – psychological and biological – as two expeditions towards a continent that never fully meet. ^{Reference Jaspers1} His insight remains strikingly current. Psychiatry stands between medicine and society, compelled to integrate the biological underpinnings of illness with the personal meanings of suffering. Yet, as the field has grown, the boundaries that once defined it have begun to dissolve.

The biopsychosocial model, proposed by George Engel almost half a century ago, was conceived as a corrective to biomedical reductionism. ^{Reference Engel2} Its humanism remains vital, but its very breadth carried an unintended consequence. By broadening the frame of reference to include every aspect of human experience, it became easier to mistake social adversity or existential discontent for clinical disorder. Integration without limits risks dissolution: when psychiatry absorbs too much of the social world, it ceases to be psychiatry. Poverty, injustice and loneliness shape mental health, but they are not mental illnesses.

At the same time, clinicians cannot bracket out the social world from their practice, nor should they. Housing insecurity, unemployment, violence and structural disadvantage shape both the onset and course of mental disorders and must be incorporated into assessment, formulation and care. Recognising these forces does not imply that psychiatry should treat poverty itself but rather that it should treat those in whom adversity has precipitated or exacerbated illness while advocating – alongside other sectors – for structural conditions more conducive to mental health.

The late 20th century witnessed a quiet but persistent expansion of diagnostic categories. Allan Frances warned against ‘diagnostic inflation’, the tendency of psychiatry to medicalise everyday variations of mood and behaviour. ^{Reference Frances3} Horwitz and Wakefield similarly described how normal sorrow has been transformed into depressive disorder. ^{Reference Horwitz and Wakefield4} The result is a subtle but profound shift in meaning: sadness becomes pathology, and treatment replaces tolerance. Clinicians encounter this every day. The grief of loss, the despair of unemployment and the anxiety of solitude are interpreted as symptoms requiring medication rather than human understanding. In this drift, psychiatry risks confusing the limits of medicine with the limits of life itself.

The boundary between adversity and illness is neither sharp nor static. It is porous, context-dependent and often discerned retrospectively through patterns of impairment, persistence and loss of function. To acknowledge this continuity is not to surrender the distinction but to recognise that drawing it is a clinical and moral task rather than a metaphysical certainty. Psychiatry must navigate this ambiguity with humility while still attempting to differentiate what stems primarily from disorder and what reflects the burdens of life.

The evidence linking social determinants to mental illness is overwhelming. Systematic reviews confirm that poverty, unemployment, inequality and exposure to violence increase risk and chronicity across diagnostic categories. ^{Reference Lund, Brooke-Sumner, Baingana, Baron, Breuer and Chandra5,Reference Patel, Saxena, Lund, Thornicroft, Baingana and Bolton6} Such findings enrich psychiatry’s understanding of vulnerability, but they must inform care without redefining the field’s identity. The response to inequality is not diagnosis but justice. The task of psychiatry is not to treat poverty but to treat those whom poverty has made ill.

This argument is not a rejection of public mental health, whose contributions to prevention, population well-being and health equity are indispensable. Rather, it is a plea to differentiate clearly between two distinct dynamics: the legitimate expansion of public mental health as a policy and research field and the much narrower trend by which everyday distress becomes reframed as a psychiatric disorder. Conflating these processes risks obscuring the structural determinants that public mental health seeks to address and inadvertently reinforcing the very medicalisation the field aims to counterbalance.

When the social becomes the clinical, we risk neglecting the political, and the very conditions that generate suffering remain unaddressed. Peter Conrad demonstrated that medicalisation often leads to ‘pharmaceuticalisation’, the translation of social and moral problems into targets for medication. ^{Reference Conrad7} This process is not merely conceptual but ethical. When psychiatry extends its remit beyond the domain of illness, it inadvertently diverts finite resources from those whose disorders are most severe and disabling. Walker and colleagues estimated that individuals with serious mental illness die 10–20 years earlier than the general population, largely from preventable physical diseases. ^{Reference Walker, McGee and Druss8} Expanding the frontiers of psychiatry towards the mildly distressed risks marginalising precisely those patients whose need for care is most acute.

These tensions are not easily resolved, and the discipline should resist the temptation to pretend otherwise. Social adversity may be a causal pathway to mental illness, yet not all adversity warrants diagnostic translation. Conversely, some psychological states rooted in hardship do, over time, cross the threshold into disorder. The challenge is to hold these dilemmas in view, to recognise that causation does not erase categorical distinctions and to maintain a conceptual framework that is clinically useful without being reductive.

The challenge, therefore, is not to enlarge psychiatry but to clarify it. Our discipline must distinguish, with humility and precision, between illness and adversity, between what medicine can heal and what human beings must learn to endure. To define those boundaries is not to retreat from the social but to engage with it responsibly. Psychiatry’s moral authority does not derive from its capacity to classify distress but from its commitment to recognise suffering in its many forms while preserving the conceptual integrity of illness.

At the heart of psychiatry lies the encounter between clinician and patient. Arthur Kleinman has reminded us that this encounter is both scientific and moral: a meeting in which meaning is co-constructed through empathy, dialogue and shared humanity. ^{Reference Kleinman9} Protecting that space – the space where suffering is recognised and care is offered – is our most urgent task. It is there that psychiatry redeems its scientific and ethical legitimacy.

As psychiatry continues to evolve in dialogue with neuroscience and global mental health, it must also cultivate an epistemic humility – an awareness of the limits of what can be measured, categorised or pharmacologically altered. The future of the discipline may depend less on its technical power than on its capacity to preserve meaning in the face of suffering.

Acknowledging these dilemmas does not weaken psychiatry’s foundations; it strengthens them by situating the discipline within the real complexity of human suffering.

Reaffirming the difference between unhappiness and illness is not an act of conservatism but of responsibility, ensuring that psychiatry remains both scientifically credible and morally trustworthy.

Psychiatry, at its best, is not the science of happiness but the practice of understanding. Its purpose is not to eradicate all forms of unhappiness but to discern those that stem from disorder from those that belong to the human condition. If the field forgets this distinction, it risks not only conceptual confusion but moral hubris. The ambition to medicalise unhappiness is, ultimately, a misunderstanding of both medicine and life. Our task is to alleviate illness, not to abolish sadness. By reclaiming that boundary, psychiatry safeguards both its scientific integrity and its human essence.