Fences Around Fences

I learned the title expression from a friend who was explaining how Kosher laws progress, for example from the prohibition "thou shalt not cook a calf in its mother's milk" to a home with two kitchens completely separating utensil, dishes and preparation surfaces for milk and meat. (Hmm, looks like veganism might be a simpler answer for the ultra-orthodox Jew). The idea of fences around fences is that a prohibition is a fence standing tightly around the taboo, but it leaves open the possibility that you might slip and accidentally stray over the fence. So you concoct another prohibition, more restrictive than the first, so that if you accidentally fall over the first fence, you're still outside the second. And because the second fence is observed by tradition, it becomes the new prohibition itself, so a third fence becomes necessary. And thus you have people, especially around special observances, strictly adhering to rules that are so far removed from the biblical prohibitions that I didn't recognize them.

This isn't quite accurate in describing the various levels of veganism, as each  deeper level of veganism is actually taking into account ways in which animals are harmed by a person's lifestyle. Mission creep might be a closer match. Here's a list of vegan issues, including the glue on postage stamps. Some vegans reject sugar because burning canefields harms the animals that live in them. And even your cruelty-free all-organic vegan broccoli has to get to market somehow. Do you reject it because the truck in which it arrived may have hit a deer, and most definitely killed thousands of bugs, on its journey from the farm? Do you cultivate your own, or live in fear that your trowal may have inflicted suffering on a worm?  It's an unachievable goal. That's okay. Lots of life philosophies centre around striving asymptotically towards some sort of perfection. This one is a concrete goal, and most people are going to agree with some aspect of "be nice to animals."

Vegans have been characterized as unrealistic, and I thought there might be a lot of holier-than-thou back-biting, but here is an example of a vegan having to choose or reject a tetanus shot, knowing it was not vegan, and both she and all the commenters seem to be agreed that accepting it was sensible and reasonable.