Psychotherapy: many things, not one.

two hands reaching between concrete pillars

15/09/2026

What is psychotherapy? This question is foundational to the philosophy of psychotherapy. Though we can meaningfully ask about the nature of psychotherapy, we shouldn’t expect a straightforward answer to this question. Psychotherapy doesn’t have a single, univocal nature. It is many things, not one.

Foundational to the philosophy of psychotherapy is the question of what psychotherapy even is. Answering this matters in several ways: e.g., to someone considering having psychotherapy, and to someone offering it; to efficacy studies in psychotherapy research, and to critiques of psychotherapy, and legal and professional regulations. However, there is widespread disagreement within the field of psychotherapy about how to answer this basic question.

Part of the problem is that we have been looking for the singular defining essence of psychotherapy. But when we look at the actual practice of psychotherapy, it is extremely diverse, and not amenable to a singular definition. Rather than trying to capture the nature of psychotherapy by looking to uncover the singular essence of psychotherapy, we should instead look to uncover the many and varied forms that psychotherapy takes in practice.

To put things more philosophically, we should reject monism about psychotherapy – that there is a singular essence that defines psychotherapy and captures all and only instances of psychotherapy. And instead, we should accept pluralism about psychotherapy – that psychotherapy is many things, not one.

The Problem with Monism

So, what’s wrong with monism? Well, let’s first observe that psychotherapy is massively diverse. Different sorts of people can be therapists, there are different environments in which psychotherapy is practiced, differences in theoretical, cultural, and ethical frameworks, differences in modality, school and approach, and differences in the sorts of topics that psychotherapy is appropriate for. Given this, monist analyses of psychotherapy face what I call the problem of diversity: the problem of constructing an analysis that is neither too narrow, nor too broad, in the face of the massive diversity within psychotherapy.

Proposals which construe psychotherapy as exclusively a matter of treating mental illness or disorder are too narrow – as there is psychotherapy for non-pathological matters like ordinary grief, and relationship problems (see French 2025a). Proposals which broaden and take psychotherapy to be at least problem focused, are still too narrow – as there is psychotherapy that supports growth and meaning making even if that isn’t a matter of addressing any problem. And then proposals which broaden even further to define psychotherapy as the use of a relationship with a therapist to produce changes in cognition, feelings, and behaviour are too broad – as not any old changes in cognition, feeling, and behaviour count. What if the changes were wholly negative, or positive, but clearly not to do with proper aims of therapy, like becoming better at maths?

Mental Health to the Rescue?

A monist could appeal to the following in providing an analysis that is neither too narrow, nor too broad: psychotherapy is psychological activity that constitutively aims at supporting good mental health.

This is not too narrow: psychotherapy might support mental health in supporting growth and psychological flourishing, quite apart from addressing any problem (mental disorder or otherwise). And it is not too broad: as good mental health is narrower than any old change in cognition, feeling, or behaviour: it is intrinsically positive and intrinsically connected to the proper aims of therapy: namely, health (unlike maths).

From Monism to Pluralism

Ultimately, though, this is not a plausible way of defending monism about psychotherapy. Why? Because mental health is many things, not one (for a defence of this mental health pluralism, see French 2025b). In some contexts, mental health is the absence of mental disorder, in other contexts it is something different, e.g., psychological flourishing.

Now, technically, even if there are various kinds of mental health, it is possible that there is just one kind that all psychotherapy constitutively aims at. But is that what we find when we look at the practice of psychotherapy? Absolutely not.

In some contexts, psychotherapy will gravitate towards a kind of mental health defined in terms of the absence of disorder – such as when CBT employs exposure therapy to treat a phobia. Here, successful therapy promotes good mental health insofar as the mental disorder (or symptoms of it) abates. Yet in other contexts, psychotherapy gravitates towards a kind of mental health defined in broader terms, independent of mental disorder status, such as to do with psychological flourishing – such as when one seeks support for ordinary grief from a humanistic therapist. Here, successful therapy might promote good mental health by promoting personal strength, and the capacity to make meaning and find purpose in the face of loss – it is not about the presence or absence or mental disorder.

Mental health is many things, not one, and reflection on the way different psychotherapeutic encounters aim at mental health reveals a further aspect of the diversity of psychotherapy: diversity in the kind of mental health constitutively aimed at. Even if every instance of psychotherapy constitutively aims at mental health, it is not the case that all instances of psychotherapy are constitutively aiming at the same thing, mental health.

This suggests that instead of monism about psychotherapy, we should accept pluralism about psychotherapy. On this view, psychotherapy is not a single, unified phenomenon, with a singular, univocal nature in virtue of which different forms of psychotherapy are forms of psychotherapy. Forms or instances of psychotherapy can differ in their constitutive aim, in particular, in the mental health they constitutively aim at. Psychotherapy is therefore many things, not one.

The Problem with Monism

Mental Health to the Rescue?

From Monism to Pluralism

Further reading