One of the requirements for infallibility according to Vatican I is that the Pope exercise “his office as shepherd and teacher of all Christians”. In determining the force of a Papal document one of the first things to check is the addressees. It is interesting to note therefore that all the encyclicals of Bl. John Paul II specify at least that they are addressed to all the bishops except four which lack any addressee. These are Redemptoris Missio, Ut Unum Sint, Redemptoris Mater and Dominum et Vivificantem. When one compares the preambles of the encyclicals it is clear that some thought has gone into their formulation. It is therefore very interesting that John Paul II should have removed these four from the area of the potentially irreformable magisterium.