Next to this one is the "If the Bible is silent on a subject, we should be, too" line. On the surface that one sounds quite reasonable. And, to be honest, for the most part it is. But, just like Jesus's silence on some subjects, just because the Bible is silent on some subjects is not a reason to conclude that it's okay (let alone, as some allege, blessed by God).
There are a few considerations to take into account on subjects on which the Bible is silent. Sometimes the Bible is silent because there is nothing to say. Take, for instance, circular squares. The Bible is silent on that subject, so it must be perfectly okay to have circular squares, right? And, of course, that's just silly. The Bible is silent on circular squares because they don't exist. The Bible nothing to say on anything that doesn't exist.
Sometimes a specific isn't mentioned because the principle involved is already taken care of. For instance, there isn't a word in the Bible about speeding. Thus, we can rightly conclude that it's perfectly okay to speed ... well, as long as you don't get caught, right? But the fact is that the principle behind this concept is covered.
Let every person be subject to the governing authorities. For there is no authority except from God, and those that exist have been instituted by God. Therefore whoever resists the authorities resists what God has appointed, and those who resist will incur judgment (Rom 13:1-2).This covers a multitude of things the Bible doesn't talk about. Is it okay to smoke marijuana? The Bible doesn't say. But it is illegal (in this country, at least), so there's your answer. How about if I cheat on my taxes? The Bible doesn't say I can't cheat on my taxes. No, but the authority that God has established says it's illegal, so the Bible is not exactly "silent" on the issue even though it is not specifically mentioned.
Here's another example. No one can argue that the Bible directly addresses abortion. It's not in there. It does, however, address the sanctity of life and the sin of murder. So just because there is no verse that says "Thou shalt not abort your baby" does not mean that the Bible is silent on the topic.
There are certainly things on which the Bible is actually silent. Is it a sin to watch TV? The Bible doesn't say. There are considerations (wasted time, perhaps, or sinful content, certainly), but a blanket "It's a sin to watch TV" is not in there. There is a lot of room for Christian Liberty that gets closed up by well-meaning but misguided Christians falling into the trap of Eve. (God said not to eat of the tree, but she said not to touch it.) I remember hearing about "no dancing" and "no movies" and "no card playing" because it might be misconstrued. But the Bible says no such thing, and on these things we might be better of remaining silent ourselves.
The most recent one I've heard is "The Bible is silent on gay marriage." Seriously? You want to stand on that? I mean, certainly there is no mention of "gay marriage" in the Bible. (Well, actually I think there were some happy weddings, but ...) Does that mean that this falls into that third category -- let's keep silent on it? I don't think so. First, the Bible has nothing to say on "same sex marriage" because the Bible defines marriage as the union of a man and a woman. As such, it wouldn't comment on two people of the same gender marrying, the marriage of a man and his dog, or any other such nonsense. It doesn't exist. Second, the Bible is not unclear on its views on homosexual behavior. Argue if you want, but it cannot be said that the Bible is silent on "a man lying with a man as with a woman" (and vice versa). So the activity is a sin. Now, would I anticipate that the Bible would need to explicitly forbid a man marrying a man? No. It falls outside the definition of "marry" and it falls within the definition of sin. I wouldn't expect the Bible to talk about a man marrying his dog, either, for both of the same reasons.
This whole "The Bible is silent" issue seems to me to be disingenuous most of the time. On one hand, there is so much about which the Bible is not silent that one has to ask, "Are you doing those?" So many people ask, "What is God's will for my life?" Too often the answers are ignored. It's God's will that you do justly, that you love your neighbor, that you love mercy, that you love God ... tell you what; when you get all that done, we'll get back to your question. Far too often the ones touting "The Bible is silent on ..." are ignoring what the Bible does say. On the other hand, in most cases that I hear "The Bible is silent" I find that the Bible really isn't silent and the goal is not to rightly determine what God wants, but to simply legitimize a pet sin. Are we really limited to the exact words of the Bible? Is our real goal to obey to the minimum level? Are we afraid that we might end up, in the final analysis, obeying too much? I don't get that at all.