Lawrence Sellin explains at Americanthinker.com that Obama is not a Pathological Liar, He is an Ideological Liar. Here's an excerpt:
Stated simply, Obama lies because the true objectives of his fundamental transformation of the United States are incompatible with American democracy and tradition.
Barack Obama's devotion to the Machiavellian dictum of "the ends justify the means" and lying as an instrument of government policy have been the tools of political extremists throughout history.
There's a name for that principle: Consequentialism. More from Sellin:
To Obama, however, they are not lies. It is acceptable to use bad or immoral methods as long as you accomplish something "good" by using them. In other words, in order to achieve what you consider as an important aim, it is acceptable to do something bad. Morally "right" consequences often necessitate morally wrong actions and what is considered "right" or "wrong" is determined by the outcome.
Now the big question is this: How could so many people have voted for such a liar when a perceived lack of honesty in his predecessor, as wrong as that was, paved the way for his election. Surely some of them are having buyers' remorse, in which case there may still be hope. However, if they too are consequentialists then the American we once knew is gone.
"Dear Leader, please tell us a lie we can believe."