Philosophical group of which Diogenes was a member (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
cynics
(Other definitions for cynics that I've seen before include "They believe the worst of people" , "Philosophers" , "They are hard to convince, sceptical people" , "They believe that people are selfishly motivated" , "They're said to know the price of everything and the value of nothing" .)