In his 1911 tongue-in-cheek essay, “Studies in the Literature of Sherlock Holmes”, Msgr. Ronald Knox coined the term Sherlockismus to describe “a special kind of epigram”, an ambiguous statement that is nevertheless memorable.
One example Knox gives is from the story “Silver Blaze”: While discussing the case with Holmes, Inspector Gregory of Scotland Yard asks him, “Is there any point to which you would wish to draw my attention?” Holmes replies, “To the curious incident of the dog in the night-time.” Gregory, puzzled, objects, “The dog did nothing in the night-time.” To which Holmes rebuts, “That was the curious incident.”
Had the person who removed Silver Blaze from his stable been an outsider, the dog would have raised the alarm. Since the dog remained quiet, Holmes deduced, the perpetrator must have been an insider — the trainer, in fact, who was trying to hobble the horse to win a bet. Sir Arthur’s earliest biographer, John Dickson Carr, exclaimed: “Call this ‘Sherlockismus’; call it any other fancy name; the fact remains that it is a clue, and a thundering good one at that.”
Joe Heschmeyer uses the Sherlockismus in a look at early Church Eucharistic theology. In one of those “D’oh!” moments that strike me much more often than you might think, I realized in reading Joe’s excellent post that the “dog that didn’t bark” also gives us a clue about what is not found in Scripture.
One of the most problematic arguments ever devised is the argument from silence. You could argue that, since you can’t find a text that proves Jesus taught/the apostles believed x, then they must not have believed it. On the other hand, since you can’t find a text which proves that Jesus/the apostles denied or contradicted x, they must have believed it. In fact, the argument from silence could be taken as a variant of the ad ignorantiam fallacy … but only when used by itself.
The problem with any argument that starts out with, “Jesus/the New Testament writers never said …,” as I’ve mentioned before, is the occasional nature of Scripture, particularly the New Testament letters. When Ss. Peter, Paul, John, James and so forth wrote, they wrote for specific reasons to address specific issues and questions. What the author and audience alike took for granted the author wouldn’t waste parchment in recapping. For instance, St. Paul would not be expected to include St. Peter in his list of greetings in Romans 16 if: a) St. Peter had not yet arrived at the time of the composition, or b) St. Paul expected St. Peter to be the first reader of the letter and to do the greetings in his name.
The “barking dog” argument isn’t exactly a classic argument from silence. Holmes’ conclusion from the dog’s silence is based on a reasonable expectation: Dogs usually bark when strangers, especially those with evil intent, prowl near their homes.
Jesus’ silence on Mosaic law’s condemnation of homosexuality can be taken as confirmation of it because, if he had said anything to approve of gay relationships, you can be morally certain the disciples and apostles would have made much of such a counter-cultural affirmation. Jesus’ silence, in view of what was taught both before and after his mission, must be construed as consent to both: Qui tacet consentire videtur.
Jesus’ silence on the prohibition of women from teaching and preaching is also a confirmation of the Church’s traditional stance on women in the priesthood. Women were prohibited from discoursing on the Law in the synagogue prior to Jesus’ earthly mission; St. Paul applied the prohibition to the Christian churches after it, as did other Church Fathers. Nor did Jesus select any women to be part of the Twelve; while St. Mary Magdalene is traditionally hailed as “apostle to the apostles”, this is in the metaphoric sense, in which any and all Christians have the capacity to act as apostles to others.
Again, if Jesus had taught anything radically different about women’s roles in the community, the disciples would have taken note of it. Indeed, Luke notes that Mary, the sister of Martha, “sat at the Lord’s feet and listened to his teaching” (Lk 10:39); many have argued that this constituted a breach of women’s traditional roles, as (presumably) only male students took such a position, and that Jesus’ words to Martha (vv. 41-42) sanction it. While the Church as a whole has been slow until recently to promote women theologians, the Catholic Church has recognized Ss. Catherine of Siena, Teresa of Ávila and Thérèse of Lisieux as Doctors of the Church, one of its highest honors. But you don’t have to be a priest to be a theologian, just as students of rabbis didn’t (and still don’t) always become rabbis themselves.
Proper exegesis doesn’t simply look at the silence of Jesus by itself, but rather in the context of what came before the New Testament and what came after it. I’ve argued before that you can’t assume the Catholic Church went wrong on any point of doctrine without implying that the Holy Spirit is either unreliable (contra Rom 3:3-4 and 2 Tim 2:13) or stopped teaching, leading and guiding the Church (Jn 14:26, 16:13) somewhere between the years 100 and 1512 (contra Mt 28:20); this is the central, fatal flaw not only of sola scriptura but of the “Great Apostasy” explanation favored by Mormons and Seventh-Day Adventists. If this is true, then it’s especially true of the ante-Nicene Church Fathers: the closer we get to the age of the apostles, the less credible any presumption of drift becomes.
The same holds true with positions taken by Catholic dissenters. The silence of Jesus is at best equivocal, at worst fatal, to the changes in Catholic teaching dissenters demand. Qui tacet consentire videtur.
 “He who is silent is seen to consent”, an old Latin jurisprudential maxim, often clarified with the clause, ubi loqui debuit ac potuit ("when he was able to speak and ought [to have spoken]", that is, when he could and should have objected or refused).