I agree entirely with Joe Trabbic that the application of Church teaching (meaning to apply general principles to specific instances) is a question of prudence and is between the individual and his conscience.
However, we have not been dealing with such claims in this debate. The arguments advanced in this debate have not been as reasonable as Joe's. Catholics have not been content to say, "I accept Church teaching and here is what my prudence tells me regarding the application of Church teaching in instance."
Instead, people's arguments have been variations of the following two points:
1. Attacks on the Catechism
2. Attempts to Re-define the Act in Question
The most common examples of the first plank, Attacks on the Catechism, are those who simply ignore the Catechism. A more sophisticated (and in my opinion sinister) variation are those who claim the Catechism does not contain valid Church teaching on this issue and thus can safely be ignored ("We are not bound by what the Catechism teaches" as the conservative Catholic proudly told me who fired me up for this debate).
Now, to save our readers a lot of research, yes the Catechism of the Catholic Church contains a variety of teachings the Magisterial weight of which varies - some have been definitvely pronounced by the Extraordinary Magisterium; most have been taught by the Ordinary and Universal Magisterium, including the teaching on lying. Granted, theologians, even saints, have argued about the morality of lying, but the Magisterial teaching on this matter has been consistent. Even the Catechism of Trent, nearly five hundred years ago, proscribes lying as something evil by its very nature, or what we would now term intrinsically evil (something that can never be done regardless of the circumstances or of one's intention).
In fact the argument made by Peter Kreeft, which I call the Just Say Know argument (just say, "I know it's so"), advances quite rightly a case for moral intuition, but falls under Plank One above by ignoring Magisterial teaching on this matter . Kreeft's argument fails becasue Church teaching trumps moral intiution for Catholics, period.
Indeed, after going round and round with my friend Deacon Jim Russell of the Archdiocese of St. Louis on this issue, he has finally publicly stated, “I concede that the Magisterium, through the Catechism of the Catholic Church, and with the authority of Divine Revelation, teaches the faithful that lying ('Lying consists in saying what is false with the intention of deceiving one’s neighbor') is a sin against the 8th Commandment, is intrinsically evil, and cannot be done under any circumstances.” (see the comboxes at the Chesterton website)
If all Catholics were conceding this in this debate, I would not be making the noise I have been.
Now, once this is admitted, the argument advances to Plank Two, Re-defining the Act in Question.
Since we know that actors in a play are not "lying", neither are fiction writers nor those who tell fables to children, we must ask ourselves why one can sometimes speak a falsehood without "lying". The obvious answer is that a lie consists of leading another into error, leading him into a false relation with reality. This is done by asserting an untruth. When actors act on stage, they are not trying to deceive the audience, who are "in on" the illusion. Thus actors, fiction writers, and story tellers are engaged in what I would call pretense and not lying.
However, in the case of the Live Action videos, while the ultimate YouTube audience was aware of the pretense (actors claiming to be pimps and prostitutes when they really weren't), the immediate audience of Planned Parenthood workers were not. This immediate audience was being deceived by the false representations of the actors, and deliberately so. They were being lied to.
And to reiterate - I am in no way saying that the lies told to the Planned Parenthood workers in any way compare with the far greater evil of abortion and of covering up for underage prostitution. There is no doubt that the wrong done to the workers pales by comparison to the wrong the workers do to young women and to unborn babies.
However, Scripture tells us that we must not do evil that good may come. And the Church is quite clear that lying is by its nature disordered, the object of which (deceiving one's neighbor) is never vitiated by any cirucmstance or good intention.
In other words, for committing or condoning the act involved in this particular situation really to be a question of prudence and not a kind of "practical dissent", the act in question can NOT be lying. If the act in question IS lying, it may never be done, nor condoned, regardless of one's prudence.