the causes

It seems to me that analysis of the causes of civic disengagement should be the most powerful part of this book, however, I find it very insufficient and unsatisfactory. Putman does analyze a lot of candidate factors, from TV to race, from money to marriage; however, the factors that are counted as causal factors, especially the weight of each factors seem more like guesses than valid conclusions. For example, of course the generation change is a powerful factor, but why is there such dramatic change between generations? The change itself does not reveal the underlying reasons to the question of civil disengagement.