The Catholic Answers website deals with various kinds of Catholic apologetics, and one of its resources is a Voter's Guide, which has occasionally been controversial. For example, a posting on the new blog Vox Nova recently complained about the Guide, though those complaints were rather outdated,  since they were aimed at what a version of the Guide used to say a few years ago (in 2004), rather than at the current version of the Guide — which has been significantly modified since that time. Nevertheless, it is worth looking at the current Guide, since it is not without problems.

The Guide picks five "non-negotiable issues" to highlight: abortion, euthanasia, embryonic stem cell research, human cloning, and homosexual marriage. Clearly, those are important issues, but why those five issues, and not others? The reason the Guide gives is that those issues involve intrinsic evils. Actions are intrinsic evils if there is no moral way of choosing to perform them, whatever the circumstances or intentions. Thus, it is never possible to choose to vote for these intrinsic evils to be performed, and the Guide suggests ranking politicians according to their position on these issues, and selecting a vote depending on the ranking.

But the Guide's method of selecting issues is based on secondary principles, rather than on what is primary. A primary principle would have to be:

So, when selecting a candidate to vote for, first the issues should be sorted into those which are a matter of opinion, and those which are a matter of conscience.

 For example, if one candidate is in favor of building two hospitals and three schools, and the other is in favor of building three hospitals and two schools, then in most circumstances it would be a matter of opinion as to which is the best policy. You wouldn't be thinking to yourself: "Well I better decide which is truly the right policy, else I will be sinning."

However, for those who have a Catholic conscience, if one candidate is in favor of permitting abortion, and the other is not, then the choice is simple: the pro-abortion policy is unacceptable, since it is an intrinsic evil, and you would certainly be sinning to favor that policy. And likewise for all intrinsic evils.

But it's not just intrinsic evils which can affect our consciences, and allow us to choose between proposed policies. Some policies can be evil, even though they are not intrinsically evil.

For example, a government is permitted to collect taxes, even if those taxes are applied unequally to people — this is not an intrinsic evil. But if a politician suggested a policy of taxing only poor people, it could be opposed, in conscience, as being unjust.

So, since non-intrinsic evils can also be opposed to our conscience, it is entirely right to also include them in our considerations of who to support, along with intrinsic evils.

Once the issues have been sorted into those of opinion, and those of conscience, we must then follow our conscience, and use issues of conscience to rank candidates. To the extent that the Guide does not make allowance for non-intrinsic evils that may affect our consciences, it gives incomplete advice.