Objection (5): Purpose as Justification
“Farmed animals are bred and raised for the purpose of being killed and eaten. Therefore we are justified in killing and eating them.”
Of course, this argument only refers to domesticated animals. It attempts to derive the justification of killing and eating animals from the purpose of their existence. The basic idea here is simple: If you generate, produce or bring something into existence for a certain purpose, then you are justified in using it to this end.
(5.1) The purpose conflicts with the interests of animals
Now, as regards inanimate things as well as non-sentient living beings, this line of reasoning would seem legitimate. If you plant a tree in order to cut it down and use its wood later on, there is basically no objection to that. However, matters seem to be quite different when it comes to sentient beings with a subjective wellbeing of their own. For here the interests of those affected come into play.
Animals would have their interests, needs and their wellbeing adversely affected by the purposes and ends of their breeders – or in a nutshell: the purpose they are destined for would make them suffer. The fact that they owe their existence to this purpose does not make any difference here (see 6).
(5.2) The logic of this argument would justify any conceivable atrocity
As regards sentient beings, the logic of this argument is obviously outrageous. For it would justify any conceivable atrocious action against a being if this being has been brought into existence for this very purpose. If you beget a child in order to abuse or sell it later on, any subsequent abuse or sale would be justified by the fact that you had such a purpose in mind right from the start.
No one in their right mind would possibly use this line of argument with regard to human beings. The least problematic and most plausible reason here is: because the purpose they are destined for would make them suffer (see 5.1). The fact that they owe their existence to this purpose does not make any difference here (see 6).
The same might well be said with regard to animals. If you breed and raise a cat for the purpose of roasting it alive in a barbecue later on, the logic of this argument would legitimise your line of action. This, however, would seem a hard action to reconcile with our common moral intuitions.
So, a practice which affects sentient beings (such as animals) adversely cannot be justified merely by reference to the fact that the beings in question have been brought into existence for this very purpose. Or else any conceivable atrocity might thus be justified.