Philosophy is at odds with common sense. One of the things peculiar to common sense is that it must not be questioned, but taken for granted. It is made up of a mass of convictions that form the solidified and uniform belief on which people act and which is the unconscious premise of most human reasoning. We use common sense to live by or to think by, but we do not think about it at all. Now suppose that in some whimsical and senseless mood someone does think about common sense. Something very startling happens. This once unchallenged authority is proved to be highly fallible. Its spell is gone. It suddenly becomes clear that common sense has had a history, and that it has varied with times and places. The absurdities of yesterday are the common sense of today. Philosophers are the people who, at the risk of being thought odd, challenge common sense. They set themselves against passively accepted 'truth' in order that the majority may be brought to reflect upon notions that have been taken for granted. Philosophers are reckless critics, insuppressible askers of questions, who do not know where to stop.