Text: I believe the majority of Americans, if they think about it at all--and keep in mind that the ones who think about it are also the ones who take the time to vote--think that our cultural life has coarsened, or even debased, and that the sense of values that just 30 or even fewer years ago meant that the majority of Americans felt no need to lock their doors has been, perhaps irretrievably, lost.
Entailment: I think that many Americans think that our cultural life has worsened.
Contradiction: It's clear that Americans universally agree that our cultural life has improved in recent decades.