When the world changes, the Torah, too, must be re-examined, not to abrogate it, but to better observe it.
Take summertime vacation for Torah learners, for example. As things stand, there are two main camps on the issue, each one absolutely convinced they are in the right, of course.
One group proclaims: Our tradition is to continue learning during the summer as before, and our fathers and rabbis are obviously more righteous and infallible than yours (by virtue of our biological and intellectual relation). Therefore, you people are clearly wrong and at least a bit evil for ignoring the obvious truth. You must hate learning Torah the rest of the year, too.
The other group proclaims: Our tradition is to take a recess from learning, and our fathers and rabbis are obviously more righteous and infallible than yours (by virtue of our biological and intellectual relation). Therefore, you people are clearly wrong and more than a bit evil for ignoring the obvious truth. You must hate learning Torah the rest of the year on the higher level that can only be attained by taking a break.
Without deciding the debate itself, I would only point out the faulty logic underlying the unexamined self-confidence on both sides: Times have changed.
One could argue people are weaker now and must vacation, as seen from the fact we all minimize fasting. Alternatively, seeing as how the summer heat is less oppressive due to widespread, cheap air-conditioning, we ought to keep on learning exactly as before. Or we should meet somewhere in the middle.
But, no. Chadash assur min hatorah…