Philosophers engage in asking questions, examining beliefs - trying to get closer to knowledge.
Sometimes finding out what is not true is progress. Blind Faith and popular opinion are also appealed to by many as a justification for their beliefs, but since these are unable to convince others to accept the justification, and have proven unreliable in our search for what is true, the Philosopher relies on the use of rational justifications alone. The passionate expression of a belief does not make it true.