Theodore Dalrymple has an excellent article up at City Journal about "The Frivolity of Evil". He worked in hospitals and prisons in Britain for 14 years and claims to have dealt with scores of thousands of perpetrators and victims of evil and violence.
Intellectuals propounded the idea that man should be freed from the shackles of social convention and self-control, and the government, without any demand from below, enacted laws that promoted unrestrained behavior and created a welfare system that protected people from some of its economic consequences. When the barriers to evil are brought down, it flourishes; and never again will I be tempted to believe in the fundamental goodness of man, or that evil is something exceptional or alien to human nature. ...There is something to be said here about the word "depression," which has almost entirely eliminated the word and even the concept of unhappiness from modern life. Of the thousands of patients I have seen, only two or three have ever claimed to be unhappy: all the rest have said that they were depressed. This semantic shift is deeply significant, for it implies that dissatisfaction with life is itself pathological, a medical condition, which it is the responsibility of the doctor to alleviate by medical means. Everyone has a right to health; depression is unhealthy; therefore everyone has a right to be happy (the opposite of being depressed). This idea in turn implies that one's state of mind, or one's mood, is or should be independent of the way that one lives one's life, a belief that must deprive human existence of all meaning, radically disconnecting reward from conduct. ...
There has been an unholy alliance between those on the Left, who believe that man is endowed with rights but no duties, and libertarians on the Right, who believe that consumer choice is the answer to all social questions, an idea eagerly adopted by the Left in precisely those areas where it does not apply. Thus people have a right to bring forth children any way they like, and the children, of course, have the right not to be deprived of anything, at least anything material. How men and women associate and have children is merely a matter of consumer choice, of no more moral consequence than the choice between dark and milk chocolate, and the state must not discriminate among different forms of association and child rearing, even if such non-discrimination has the same effect as British and French neutrality during the Spanish Civil War.
I suggest you read the whole essay, as it's quite compelling. I've written about total depravity before, and I think only someone incredibly naive could possibly believe that mankind, or any individual, is "basically good".
(HT: Wretchard.)