ruthless criticism

"But if constructing the future and settling everything for all times are not our affair, it is all the more clear what we have to accomplish at present: I am referring to ruthless criticism of all that exists, ruthless both in the sense of not being afraid of the results it arrives at, and in the sense of being just a little afraid of conflict with the powers that be."
-Marx, in letter written to Arnold Ruge, 1843.