III. Chastening Reminders
Cannibalism is a chilling reminder of our humble origins in animal kingdom. To cannibal, we are no better and no more than cattle or sheep. Cannibalism confronts us with irreversibility of our death and its finality. Surely, we cannot survive our demise with our cadaver mutilated and gutted and our skeletal bones scattered, gnawed, and chewed on?
IV. Medical Reasons
Infrequently, cannibalism results in prion diseases of nervous system, such as kuru. The same paternalism that gave rise to banning of drug abuse, outlawing of suicide, and Prohibition of alcoholic drinks in 1920s - seeks to shelter us from pernicious medical outcomes of cannibalism and to protect others who might become our victims.
V. The Fear of Being Objectified
Being treated as an object (being objectified) is most torturous form of abuse. People go to great lengths to seek empathy and to be perceived by others as three dimensional entities with emotions, needs, priorities, wishes, and preferences.
The cannibal reduces others by treating them as so much meat. Many cannibal serial killers transformed organs of their victims into trophies. The Cook Islanders sought to humiliate their enemies by eating, digesting, and then defecating them - having absorbed their mana (prowess, life force) in process.
VI. The Argument from Nature
Cannibalism is often castigated as "unnatural". Animals, goes myth, don't prey on their own kind.
Alas, like so many other romantic lores, this is untrue. Most species - including our closest relatives, chimpanzees - do cannibalize. Cannibalism in nature is widespread and serves diverse purposes such as population control (chickens, salamanders, toads), food and protein security in conditions of scarcity (hippopotamuses, scorpions, certain types of dinosaurs), threat avoidance (rabbits, mice, rats, and hamsters), and propagation of genetic material through exclusive mating (Red-back spider and many mantids).
Moreover, humans are a part of nature. Our deeds and misdeeds are natural by definition. Seeking to tame nature is a natural act. Seeking to establish hierarchies and subdue or relinquish our enemies are natural propensities. By avoiding cannibalism we seek to transcend nature. Refraining from cannibalism is unnatural act.
VIII. The Argument from Progress
It is a circular syllogism involving a tautology and goes like this:
Cannibalism is barbaric. Cannibals are, therefore, barbarians. Progress entails abolition of this practice.
The premises - both explicit and implicit - are axiomatic and, therefore, shaky. What makes cannibalism barbarian? And why is progress a desirable outcome? There is a prescriptive fallacy involved, as well: