One claim often made by those advocating comparative proofs of vegetarianism is that eating plant foods is instinctive, while eating animal foods is non- instinctive or unnatural. Accordingly, the question of whether particular actions are due to instinct or intelligence is controversial and a source of major disagreement.
Individual intelligence can override instinctive restraints.
All our difficulties, as well as all our possibilities have come about because the sapient brain overrode the last restraints, indeed the directiveness, that instinct gives to animals. What remains to man after these basic conservational restraints of instinct are extinguished is a super- intelligence that filters all major categories of human behavior through the cortex. He is a thinking animal with a complex brain, a supremely energized mammalian brain that must now control, direct, guide his behavior. The old passions, energies, and drives no longer have built-in censors. The major question to address here is whether eating meat or animal foods is instinctive or not.