This book is a part of the ongoing enterprise to understand the nature of human health and illness. This enterprise has expanded dramatically during the last decades. A great number of articles, as weIl as a fair number of monographs, on this topic have been published by renowned international publishers. In this discussion most participants share the idea that health is a partially normative concept, Le. that health is not a phe­ nomenon which can be wholly characterised in biological (or otherwise descriptive) terms. To ascribe health to a person is eo ipso, according to this line of thought, to as­ cribe a positively evaluated property to this person. Moreover, most debators share the idea that health is a holistic property, belonging to the person as a whole, whereas dis­ eases, injuries and defects are entities (or properties of entities) which can be very lim­ ited and and normally affect only a part of the individual. My own monograph belongs to this tradition. A feature of my position, which is not universally acknowledged in riyal theories, however, is my emphasis on the notion of ability as a fundament in the theory of health. In my formal characterisation of health I view it as astate of a person which is such that the person has the ability to fulfi1 his or her vital goals.

I: Action Theory.- 1. Towards an ontology of episodes.- 2. Towards an analysis of the concept of action.- 3. On complex actions: accomplishments and projects.- 4. On the explanation and determination of actions.- 5. On the logical form of action-explanations.- 6. On the logical form of interaction.- 7. Towards a theory of ability and disability.- II: Action-Theory as a Basis for the Theories of Health and Welfare.- 8. On the notion of health as ability.- 9. On the concepts of vital goal and happiness.- 10. On the multiplicity of health concepts.- III: Action-Theoretic Applications in the Theory of Health and Health Care.- 11. On the technical notions of disability and handicap: the WHO context.- 12. On the complexity of autonomy.- 13. A sketch for a theory of health enhancement.- 14. On the role of compulsion in mental illness. The case of forensic psychiatry.- IV: Summary of Basic Concepts.