Passé, présent et avenir en démographie

SUMMARY In spite of the commonly accepted opinion that the study of the past is of no use, it is essential in demography especially in order to improve its two main applications : diagnosis and forecasting. Diagnosis assumes a typology which can be developed only if similar cases in the past are taken into account. Forecasting is based on the inertia of demographic phenomena which has never been thoroughly studied. To achieve such a study, it is necessary to have numerous chronological series which reach far back into the past. Thus it will be possible to know more about the relationship between the past, present and future and, consequently, to improve forecasting and assess its limits.