The aim of this article is to identify a characteristic of delusions: that which makes them pathological. It may appear somewhat strange at first because one believes that delusions are precisely a pathological alteration of the mind. However, some authors have shown that although pathological delusions are the most studied, not all delusions have necessarily harmful consequences for the delirious subject or for others. Hence, it seems pertinent to question what makes delusions become a pathological state. Here I support the phenomenological perspective in which delusions are considered experiences. Specifically I follow Gallagher's Multiple Realities model that holds that delusions are an alternative reality which I compare with the perspective that delusions are false beliefs. I hold that the two perspectives are not completely incompatible and that delusions are above all experiences. From this model I try to explain why delusions are not always pathological.