This article from 2008 helps explain why a liberal, union, public school, geometry teacher in Philadelphia berated a 16-year-old high school sophomore for wearing a Romney t-shirt to class (mentioned in my last post). 

How Ideology Colors Morality

Conservatives and liberals reside in different moral worlds.

Liberals tend to think that conservatives are either stupid or evil.  They see George W. Bush as a buffoon and Dick Cheney as a nefarious architect of doom.  These two options strike liberals as the only possible explanations for why someone would adopt a conservative agenda.   Conservatives must be either be confused about what morality demands of us in the political sphere, or they must recognize the demands of morality and simply ignore those demands, in pursuit of power or lucre.  Conservatives have no more a flattering conception of liberals.  For their vantage point, liberals either look hopelessly naïve (read "stupid") or dangerously corrupted (read "evil").   Liberals are either tree-hugging fools or calculating agents of moral degeneracy. Why is this?

One answer is that liberals and conservatives each make the same false assumption about the other side: they assume that their opponents share the same basic moral values.   Suppose you and I share the same basic values, but you advocate some policy that I oppose.  That means one of us is either making a mistake about what our shared values entail or willfully pursuing something we know to be immoral.  One of us is stupid or evil.  But there is another possibility: perhaps we have some different basic values.  Perhaps we are both pursuing exactly what our values demand of us, but, since those values differ, we are pursuing different political agendas.

Read the full article.