I think philosophers think too highly of "purifying" the mind. From what I've seen, trying to only have "pure" thought makes it very easy for people to avoid their problems and go into denial. I'm all for having good intentions, but the notion that good actions can only come from focusing on goodness is ridiculous. Tough decisions require growing up and accepting that an action may cause some bad consequences. How would someone be able to develop a breakthrough medication if it wasn't perfect, but better than every option so far? How would democracy function if people were not prepared for slow and incrimental process, and instead gave up and said they would never vote for "the lesser of two evils?"
Some people still hold onto the old Enlightenment idea that man could become perfect somehow by only doing the best of things and thinking the best of thoughts, but until our notion of "goodness" is something more substantial than whatever we want our lives to be at the moment, how are we not going to end up living the shallowest of lives?