Depression is often defined partly in terms of anhedonia because psychiatry has historically focused on observable symptoms and impairments, and anhedonia is a relatively specific, clinically useful phenomenon: a reduced ability to experience pleasure or interest in normally rewarding activities.

The concepts eudaimonia and kakodaimonia come from a different intellectual tradition—ancient Greek ethics and philosophy—and refer to broader states of flourishing or ill-being.

• Anhedonia = diminished pleasure, interest, motivation, or reward responsiveness.
• Eudaimonia = living well, flourishing, meaning, virtue, fulfillment.
• Kakodaimonia (less commonly used) = a state of ill-being, misery, or a life going badly.

From a philosophical perspective, depression often appears closer to kakodaimonia than merely anhedonia. Many depressed people describe not just a loss of pleasure but:

• loss of meaning,
• hopelessness,
• alienation,
• self-loathing,
• inability to pursue valued goals,
• a sense that life itself is diminished.

These experiences concern overall well-being rather than pleasure alone.

So why doesn't psychiatry frame depression as "kakodaimonia" or loss of "eudaimonia"?

1. Psychiatry aims to identify symptoms, not evaluate whole lives

"Eudaimonia" concerns whether a person's life is flourishing. But someone can:

• lack eudaimonic fulfillment without being clinically depressed, or
• have a meaningful, objectively successful life while experiencing major depression.

Psychiatric diagnoses try to identify a disorder rather than judge whether a life is going well.

2. Anhedonia is more specific

Many forms of suffering, grief, poverty, social exclusion, or existential crisis reduce eudaimonia. If depression were defined as "lack of flourishing," it would be difficult to distinguish from many non-pathological forms of unhappiness.

Anhedonia is narrower and therefore more diagnostically useful.

3. Depression is not always low pleasure, but reward processing is central

Modern research suggests depression often involves disruptions in reward anticipation, motivation, learning, and enjoyment. "Anhedonia" captures this cluster better than broad philosophical concepts.

That said, many researchers now argue that anhedonia itself is too narrow. They increasingly study:

• meaning and purpose,
• social connectedness,
• agency,
• psychological well-being,
• eudaimonic well-being.

These are much closer to the eudaimonic tradition.

4. Eudaimonia is partly normative

To say someone lacks eudaimonia implies some conception of what constitutes a good human life. Different cultures and philosophies disagree about this. Psychiatry generally tries to avoid embedding a particular moral theory into diagnosis.

A deeper way to put it

One could argue that anhedonia is a symptom-level description, whereas kakodaimonia is a life-level description.

Depression may produce a state resembling kakodaimonia—a pervasive condition of ill-being and inability to flourish—but clinicians describe it through more specific mechanisms and symptoms such as depressed mood, anhedonia, cognitive distortions, sleep disturbance, and impaired functioning.

In that sense, the concepts are not really competitors. A philosopher might say depression is a form of kakodaimonia or a severe obstacle to eudaimonia, while a psychiatrist would describe one important mechanism within that state as anhedonia.