Good question.

There is actually this section here:

Philosophy of Politics


One definition of philosophy is "the rational investigation of the truths and principles of being, knowledge, or conduct."

http://dictionary.reference.com/browse/Philosophy

It intrigues me that when people are asked why they do this or that, what their purpose is, their answer is not forthcoming, or horribly unconvincing.

Apart from anything else it is then hard work to have to guess their purpose for them to try to get along.

The difference here in question tends to be that while philosophers really do try to tell the truth, and often at some considerable risk to their own well being, politicians...........etc.

-- RH.