"But let us suppose that it should turn out that those who refuse vaccination are mistaken in their judgment. Let us say that the Church issues a directive stating that there is no illicit cooperation with abortion in the case of these vaccines. Nonetheless, the obligation to follow an erroneous conscience remains. We cannot oblige a person to violate his conscience, but we must respect that decision even if we ourselves are convinced that it is wrong. On all of these grounds, therefore, one can argue forcefully that parents who do not want to have any association with the practice of abortion, and who refuse to have their children vaccinated, should be free to do so. Certainly, it would be wrong to force parents to vaccinate their children. We cannot compel anyone to act against his will except as punishment for a crime. Beyond this, however, it is difficult to know what more one can be said about the refusal to vaccinate on the basis of conscience. Catholic teaching holds that there is an objective moral order that ought to guide the activity of conscience. Obviously, we are not free to decide whatever we wish—every moral person will agree on this point. The moral order that ought to guide our conduct does not depend upon the judgment of Church officials, but exists independently of all human decision. The mind must conform to reality in order to know the truth, but in the absence of any announced position by the Church, one can only appeal to the authority of one’s own conscience, which will hopefully be well-grounded in observation and sound thinking. The more our appeal takes its bearings from a knowledge of the facts and the true principles of morality, the more likely it will be that our exercise of conscience will successfully choose the good."