Philosophy was born outdoors and is now back on the streets. Its institutional cornering, which expels it from schools and universities, has as a counterpart a new vitality, a collective desire to radically question our ways of living and to learn to think again. Philosophy was born of the discussion, the war between cities and the rivalry between conceptions of the world. Today, another war has put our lives and budgets in serious crisis. Faced with this, philosophy is a thought that transforms life. It is a system of concepts but also an attitude. Philosophy is living thought. It does not offer formulas or recipes, but puts each in the situation of thinking their particular matters as common problems. How to live, how to think, how to act? From these questions, philosophy is neither useful nor useless. It is necessary. Necessary for the concrete life of each one of us and for our societies in crisis. Some people think that philosophy should be protected and defended as if it were a museum piece or an endangered species. On the contrary: philosophy can not be preserved, it has to be practiced and exposed. It is not a matter of stretching the past of a dying history, but of opening ourselves to the present of an unfinished philosophy. Unfinished philosophy for a world that shows symptoms of exhaustion: this is the main challenge that challenges us, philosophers and non-philosophers, today