There is the old trichinosis theory, which posits that pigs were a source of the disease, but that has been largely discredited. One of my favorite justifications—at its heart hedonistic—is that since pork was the fattiest, most delicious meat, it was prohibited to steer the weak willed away from gluttony. In her book Purity and Danger, anthropologist Mary Douglas says that because pigs are cloven hoofed, but not ruminants like cows, they veered from the ancient Israelite conception of wholeness and holiness, and as such, were deemed untouchable.
Regardless of the source of the laws, Jews had a hard time disentangling themselves from swine. In European society, the very thing that Jews assiduously avoided became associated with them in the most hateful of anti-Semitic practices and images. In her book The Singular Beast: Jews, Christians, and the Pig, French anthropologist Claudine Fabre-Vassas exhaustively documents how Jews were taunted—19th-century French boys twisted the edge of their garments into what looked like pigs' ears, shook them, and grunted at Jews in the street, and more gruesomely, in the Middle Ages, Jews convicted of murder were hung upside down, like dead pigs.
Even today, a secular Jew like David Rakoff views pork differently than other meats. In perhaps my favorite piggy confessional of the year (buried in a writerly supplement to Gourmet), he writes that of all treyf, the pig packs more symbolic weight than other proscribed foods. "Shellfish is nowhere near as freighted as pork. Many a Dungeness devotee would never dream of touching swine." Rakoff loves pork, but it is a sad mnemonic: "As a Jew Who Eats Pork, extolling the boundless perfection of the baby pig at Great N.Y. Noodletown on the Bowery necessarily requires a simultaneous split second of silent acknowledgement along with my blithe rhapsody that this is the meat of my grim history. Otherwise, I'd just be a guy eating pork."
Beyond Biblical prohibition, there is the sense that as much as they can disgust us, pigs are rather like us, too. Among regularly eaten beasts, pigs are probably the closest to human. They're intelligent, social, relatively unfurry—and they resemble us on the inside. When Pollan looks at his dead pig in the woods, he is swept with revulsion. "I'd handled plenty of viscera in the chickens I'd gutted on Joel's farm, but this was different and more disturbing, probably because the pig's internal organs … looked exactly like human organs. Which is why, as I recalled, surgeons hone their skills by operating on pigs." Indeed, the boundary between human and porcine seems uncomfortably blurred in folk and literary traditions across the centuries: Odysseus' gang was turned into pigs by Circe, a baby turns into a piglet (shown here on a baby tee) in Alice's Adventures in Wonderland, and chef-pig statuettes are a not-insignificant category among kitsch collectibles.
This ambiguous quasi-human quality, coupled with an ancient tradition of taboo, is what makes pigs so symbolically rich. While the animal rights movement may garner its biggest headlines with luxury products like foie gras and caviar (although this comix pamphlet is pretty harrowing), for the philosophical foodie, there seems to be more resonance—a certain gallows empathy—in examining the death of the far more ordinary pig.
Thanks to Bruce Cole of Edible San Francisco and Peter Parshall at the National Gallery of Art for their bibliographical help.