 Although most authors argue that there has been a shift in Church teaching over the last two millennia from acceptance and toleration of slavery to opposition, some Catholic writers reject this claim, insisting that there has been no such change in the Magisterium.One reason for this insistence is that authors who argue that the Magisterium has changed have pointed to this purported shift in teaching as setting a precedent that Church teaching has changed to be compatible with changes in social mores and morality.Cardinal Avery Dulles makes the following observations about the Catholic Church and the institution of slavery

In a modern work that denies any fundamental change in the church's teaching over the centuries, Father Joel Panzer writes