Are humans optimistically biased?

I once attempted to educate my fellow human being on the atrocities that happen in life. Like the islamo-fascist government that's trying to take hold in Britain and the saddening rate of poverty and disease in Africa. But he tells me that he likes to see the cup as half full instead of half empty, and proceeds to turn on the tv and watch Nascar. I know optimism is good, but when we sink into its rut to the point that we're unwilling to acknowledge the injustice, indignation, and the negative in this world haven't we just become the very problem that plagues this world?