Miranda and Public Safety

Most of us are raised to do right things and to tell the truth...and that is the ideal of our society. So...where does this concept of Miranda come from and why? IMHO, someone used the trees to hide the forest. Some mutt does something wrong and when caught fesses up to it because of some ingrained moral instinct. We say, "No, No, you must not admit your folly or tell the truth." Where does that come from and what social interest is served by that silliness. You say that some authorities will abuse the arrested person and MAKE him or her confess? OK...where is it written that the lawyer cannot challenge the confession on that ground? And where is it written that once a person is actually arrested that the authorities cannot be...