Gil, at his excellent blog, brings an essay by Rabbi Slifkin (PDF) on the great debate of whether or not elephants are capable of jumping.
The debate seems to be between Tosafos, on the one side, who says that elephants can jump, and modern science, which states that elephants are incapable of jumping.
Of course, as Rabbi Slifkin puts it, some people will take the view that "if Tosafos says that elephants jump, then elephants jump!" End of story. He reasons simply that Tosafos, having lived in twelfth century France, never saw an elephant and never even saw an accurate drawing of an elephant, and so could easily make a mistake as to whether or not it can jump.
Fanatics aside, Rabbi Slifkin then goes on to ask how this matter should be presented to students. At one points, he wonders if we should just throw up our hands and say "we don't know." However, as he puts it:
One might suggest that it is better to simply state that we don't know the answer. That may sometimes work. But the odds are that the student will eventually discover the truth about elephants anyway - it's only a Google-search away.
This, of course (IMHO anyway) is the second (unstated) reason for the internet ban in Lakewood and other places (I know of someone who enrolled his son in a yeshiva here in Brooklyn and was told that an internet connection at home was unacceptale. They relented when the father pointed out that he was an IT professional and that his livelihood [and their tuition payments] depended on his internet connection). It is to prevent people from access to information which might possibly upset their simplistic world view. The same type of people who will believe that elephants jump simply because Tosafos says so, are the same ones who don't want to allow any fact that might upset the infallibility of Chazal.
I find it interesting, of course, that Catholics are castigated for their belief in papal infallibility. Yet, they only extend this doctrine to when the pope speaks ex cathedra. We, on the other hand, in some segments of our population, have extended this infallibility to not just one person, but to a whole class of people, and on just about anything that they utter. And yet, we castigate them for the doctrine of papal infallibility. Mr. Pot, meet Mr. Kettle.