At first sight the answer to the question posed in the title to this chapter seems to be exceedingly simple. Since ageing is a series of biological changes occurring in all humans at all ages and at all times, then old age is the name for the final stage of that programme during which decline itself accelerates markedly. The only thing that has to be settled is the point at which individuals reach that final stage, and this is evidently a particular birth anniversary, the 50th, 55th, 60th, 65th, 70th, or whatever. Any person who has passed that anniversary is to be considered as being in old age. The proportion which the total of these people makes up of the whole is the obvious measure of how old a population is in comparative terms.
This certainly seems to be the account assumed by demographers and, at least initially, by other bodies of persons to whom ageing is important, the doctors, the politicians, the administrators, the economists, and the lawyers. Supposing that calendar age, age last birthday, is symmetrical with biological change, they proceed as if everyone after the nominated birthday, everywhere and at all times, is and has been in a uniform state of physical, mental, and even social disability--in the sense of lacking social status. The fact that this nominated birthday varies from country to country, activity to activity, gender to gender, and from time to time is to be explained in this account by cultural and other differences in the acceptable degree of biological decline which has to be manifest before the final stage is proclaimed to have arrived. With this, and other implications allowed for, such as the degree to which the biological process may vary between individuals and their social and historical situations, it is possible to proceed as if old age were a homogeneous condition. Everyone in it can be expected to show forth from its onset the decayed appearance which we all know so well, the incapacities, physical and mental, the accelerating deterioration, the growing lack of autonomy and dependence on others, younger others, which make old age so problematic.
Once such a summary description of old age is written out in such terms as these it is recognized as distortive and exaggerated, that in spite of its obvious practical conveniences it misrepresents persons in late life with whom we are