Disambiguate, please. Do you mean you want to understand (a) how to get people to stop talking, or (b) why anybody would prefer being silent to talking? (a): I recommend moving to a quiet area. Humans are social creatures. If you are in a quiet area, suggest that they move or be quiet. (b): Quiet allows for reflection & concentration; though humans are social creatures, they also need time away from sociability, in places such as libraries.