If it is just about ability to suffer , what if we kill animals for consumption as long as we can ensure they don ' t suffer anymore than living their lives normally would have caused ? The animals can live and roam freely and when it is time to slaughter one , an animal with no close attachment or dependents is lured off to a secluded are where it is instantly and painlessly killed and the other animals if they do notice it is missing would just assume it left . That solves the suffering issue as why does it matter if an animal can suffer if eating the animal causes no suffering to occur ? This logic could also be extended to humans . If the reason we can ' t kill or eat them is just because they experience suffering , can we offer shelter to hobos and once they are asleep , move them to rest on a steel block where another steel block weighing multiple tons is dropped directly on their head . Their brain will be completely destroyed before they can even process the experience , so there is no change they could possibly suffer . That was just my quick attempt to explain a perfectly sufferfree system to kill so that the argument of even a decapitated or shot head may still have blood flow in the brain and conscious suffering for a few seconds .