"The moral tradition says: we have many natural tendencies, but as ethical human beings we have to try to overcome natural impulses. For example, we are naturally violent; human beings are naturally very selfish, trying to focus their decisions on themselves, but ethics is always saying: you have to fight against these natural tendencies. You cannot be all the violent that nature commands, you cannot be everything selfish that nature asks for. So if you tell me that procreation is natural, being natural does not show it to be moral. On the contrary, forgotten Brazilian philosophers like Tobias Barreto put exactly the opposite. Tobias Barreto thought that when something is natural it is bad, and we have to fight it. (The enslavement of one people over others is natural, but it is cultural that slavery must not exist.) So do not tell me that procreation is natural and so we have to do it. All human morality is unnatural; all human morality is artificial, just as our feeding systems in our sophisticated restaurants are also artificial and unnatural. What is the animal that eats the way we eat? Even our sexuality is artificial; it is not purely instinctual, but largely symbolic. If you had that argument in your sleeve, you would still have to show that what comes from nature is moral, because there are many arguments showing that what comes from nature can be opposite of morality."