One cannot look at mental pathology as an accident or a dysfunction reserved to some human beings, therefore becoming strangers to common humanity. On the contrary the psychotics concern us and question moreover our common presumptions insofar their delusions interrogate metaphysical questions about identity, relationship to the others, reality, origin and end, and, more generally, human condition. They nevertheless do not behold a special lucidity towards these but they compel us to consciousness regarding the frailty of our common daily experience. We will try to unfold in order to understand the peculiarities of the paranoiac trouble and stress upon the fact that in front of the fundamental classical infantile interrogations dealing with the world, the meaning of things, the paranoiac does no more ask questions to himself nor to anyone: he has the conviction that he already knows.