Our thinking about persons owes much to ancient and medieval debates – debates that often do not mention “person” but may be about happiness, practical deliberation, freedom, substance, Jesus Christ, the Trinity. On Boethius’ famous definition (“a person is an individual substance of a rational nature”1), which Aquinas approved:2 persons are individuals (not classes, aggregates or universals); substances (not relations, properties or abstract ideas); instances of a natural kind (not social constructions, legal fictions or philosophical categories); and distinguished by rationality (not sentience, activated intelligence or developmental stage). To this medieval legacy our modern concept of person adds various notions derived from the moral thought of thinkers such as Rousseau and Kant. Persons are not objects: they have a unique form of value (“dignity”); they cannot serve purely as means to other people’s plans; their exercise of choice is self-making and self-ruling (they have “autonomy”); they are to be treated as of equal status, and offered any necessary help or protection (shown “respect”). These are the essentials of the view of persons to which radical philosophers today often respond, sometimes agreeing but often exaggerating one element at the cost of the others. This view is also closer than any other academic view of popular thinking on persons, though the radical attack is undoubtedly affecting popular perceptions.