A person whose conscience is in doubt should try to resolve the doubt. One willing to proceed while in reasonable doubt about what is right is willing to do wrong, and to be willing to do wrong is itself wrong.
Doubts arise from uncertainty about facts, uncertainty about norms, and the appearance of conflicting responsibilities.
Where doubts about facts make it difficult to apply a rule of positive law and the law itself offers no help in resolving the doubt, one may resort to reasonable presumptions. But where a doubt of fact leads to difficulty in determining the gravity of an act recognized to be immoral, one should assume that the facts are such as to make the act more seriously wrong. Where the doubt affects the judgment whether the act is right or wrong, what one ought to do depends on whether acting in a state of doubt will involve a violation of any of the modes of responsibility.
Other doubts arise from uncertainty about norms. Where the norm is a rule of positive law, it is a question of fact whether it exists and a question of legal interpretation whether it applies to the action under consideration. In the case of a truly doubtful law, one has no obligation to obey; but a law is not truly doubtful when a preponderance of expert opinion holds that it exists and is relevant. Where the norm is not a rule of law but a specific moral norm, doubt can arise for a Catholic only in the absence of clear Church teaching on the matter. Then one should be guided by the consensus of theologians, if one exists; if not, one should refrain from the action if one would not otherwise have any responsibility to do it; or, supposing such a responsibility, one should perform the action if one judges it more likely to be permissible but refrain from it if one judges it more likely to be impermissible.
The method of resolving doubts about rules of positive law described here is what has been called “equiprobabilism.” The method of resolving doubts about moral norms is analogous to “probabiliorism.” Both probabiliorism and the present approach set aside theological opinions when there is a clear teaching of the Church and also when, lacking such teaching, particular theological opinions are not part of a solid theological consensus; both also discourage the arbitrary multiplication of supposed obligations. Moreover, both differ from probabilism by taking as a criterion the greater likelihood of truth.
However, the present approach is also fundamentally different from probabiliorism. In the legalistic context in which probabiliorism developed, the central question was whether one was bound by a law or free to do as one pleased. By contrast, the nonlegalistic assumption of the present approach is that one ought always to act in pursuit of human goods; thus, the conclusion that one possible norm is not operative in a particular case simply makes it clear that one has a responsibility to choose and act according to some other norm.
The third way in which doubts of conscience arise is from the appearance of conflicting responsibilities. There can, however, be no such conflicts at the level of moral principles, and cases of apparent conflict are usually cleared up by reflection on the facts and the relevant norms.
Where one has assumed a false norm, the conflict cannot be resolved until the error is corrected. Where no false norm is involved, the appearance of conflicting responsibilities results from the fact that nonabsolute moral norms have not been sufficiently specified. As for conflicts of duties in the strict sense, they are resolved by formulating a norm in accord with the principle of fairness. But when duties would require one to do something contrary to an absolute norm, the latter prevails.
In many cases, apparent conflicts impelling one to do something contrary to an absolute norm are resolved when the morally right course, previously ignored because it is unappealing, is accepted as a practical possibility. In other cases of apparent conflict involving the eighth mode, the resolution lies in clarifying how relevant norms apply to the choices under consideration. The eighth mode rules out a choice detrimental to a human good, but it does not rule out accepting foreseen side effects detrimental to a good (although some other mode may do so in a particular case). Classical moral theology dealt with this question—when one may accept side effects which it would be wrong to choose—by what is called the “principle of double effect.”
Cooperating with someone who is doing something wrong raises the same issues as those just considered. “Formal” cooperation is altogether excluded; it is present when one’s purpose includes the committing of sin by another, or when what one personally chooses is identical with or includes the immoral proposal of the person with whom one is cooperating. Other cooperation is “material.” In some cases it may be permitted, but very often it is ruled out by other moral considerations, especially fairness. The conditions under which Christians may cooperate even materially in evil are especially stringent, since refusing to cooperate is often a requirement of mercy and an important way of bearing witness to the truth.