Lack of understanding develops between people of widely different age groups, particularly between children (usually from the age of adolescence) and parents, grandparents etc. This lack of understanding may lead to the rejection of the children by the parents or, at a later stage when the parents are in need, the rejection of the parents by the children. It may lead to: family breakdown; juvenile delinquency; hooliganism and assault on older people by youth gangs; destruction of property; student unrest. Equally it may lead, because of fear and prejudice, to rejection of new ideas by older people and resistance to change. On the other hand, the abilities of youth may be overvalued in comparison with those of older people, leading to early retirement, unemployment and neglect of middle-aged and older persons.
The generational conflict, or conflict between age-groups, is largely due to the educational revolution, which gives the adolescents of today intellectual tools that their parents very often did not have. It is also due to the "knowledge revolution", making the knowledge of the parent generation more irrelevant. This is not only because there has been a quantitative accumulation since they formed their images of the world, but also because of the qualitative changes of paradigms that seem to take place with increasing speed today. There is little reason to believe that these trends will not continue, and the net result is increasing irrelevance, dissimilarity, and heterogeneity, between generations.
The conflict between traditional civilizations and the new elements of industrial civilization break down structures which do not adapt themselves to new conditions. Their framework, sometimes rigid, was the indispensable prop to personal and family life; older people remain attached to it, the young escape from it, as from a useless barrier, to turn eagerly to new forms of life in society. The conflict of the generations is made more serious by a tragic dilemma: whether to retain ancestral institutions and convictions and renounce progress, or to admit techniques and civilizations from outside and reject along with the traditions of the past all their human richness. In effect, the moral, spiritual and religious supports of the past too often give way without securing in return any guarantee of a place in the new world. (Papal Encyclical, Populorum Progressio, 26 Mar 1967).
Urban life and industrial change bring strongly to light questions which until now were poorly grasped. What place, for example, in this world being brought to birth, should be given to youth? Everywhere dialogue is proving to be difficult between youth, with its aspirations, renewal and also insecurity for the future, and the adult generations. It is obvious to all that here we have a source of serious conflicts, division and opting out, even within the family, and a questioning of modes of authority, education for freedom and the handing on of values and beliefs, which strikes at the deep roots of society. (Papal Writings, 14 May 1971).