While religion is often used to justify eating meat, it is rather interesting to note that some significant Christian thinkers have seriously considered the ethics of the matter. This does make perfect sense. After all, the bible is clear that killing is a sin and it would certainly be unfortunate to end up in hell for eating a hamburger.
St. Aquinas addressed the matter of killing living things in his Summa Theologica. His approach is to raise and reply to three arguments against the killing of animals (primarily for the purpose of consuming their flesh).
In his first argument he contends that it appears to be unlawful to kill living beings. His concern, is of course, that breaking God‘s law leads to damnation. He further notes that divine providence seems to command that all living beings be preserved. As such, killing would be against divine law. Given his ethical theory, this would also make killing animals an immoral act.
In response to this, Aquinas avails himself of St. Augustine’s argument about eating meat. Augustine’s argument for the acceptability of eating meat actually has three parts.
First, he contends that the injunction against killing does not apply to trees (because they “have no sense”) or animals (because they “have no fellowship with us”). Thus, the injunction against killing does not apply to plants or animals. Of course, there are those who contend that trees do have sense (or at least some sort of awareness) and fairly strong case can (and has) been made that animals to have fellowship with us. As Hume argued, animals seem to differ from us mainly in degree rather than in kind.
Second, Augustine makes use of some of Aristotle‘s philosophy to present a teleological argument for eating meat. He begins with the assumption that it is not sinful to use something for the purpose for which it was created. Following Aristotle, he notes that there is an order of things in the universe and asserts that the “imperfect are for the perfect.”
Interestingly, he notes that this follows the process of reproduction: beings go from a lower to a higher state. In the case of man, he asserts, there is “first a living thing, then an animal, and last a man.” he then returns to his main focus, and contends that because plants have mere life, then they exist as food for animals. Since animals are inferior to men, they are thus food for men. As such, it is morally acceptable for humans to eat meat.
This argument, obviously enough, assumes that there is a hierarchy of beings and that being lower down on this hierarchy allows the higher ups to eat one. This would certainly seem to imply that beings higher than man could lawfully eat men. Fortunately for us, angels do not appear to have a taste for human burgers (perhaps they subsist on angel food cake).
Put a bit more roughly, his argument seems to be that we are better than animals, so we can eat them. This “we are better than you” reasoning has, of course, been routinely used in history to justify a wide variety of misdeeds ranging from oppression to slavery to outright genocide. As such, it certainly seems to be a justification that is morally questionable. After all, if we are truly better than them, we should act that way.
Third, Augustine presents a theological argument for eating meat. He begins by noting that animals need to eat plants and men need to use animals for food. This, of course, typically requires killing the plant or animal. This is justified because the bible says it is: (Gn. 1:29,30): “Behold I have given you every herb … and all trees … to be your meat, and to all beasts of the earth” and (Gn. 9:3): “Everything that moveth and liveth shall be meat to you.”
This argument assumes that God exists and has given us permission to eat animals. Obviously enough, those who do not share these assumptions will find the argument rather less than compelling. Another point that can be contended is his assumption that humans need to eat animals. While this might have been true in the past, today there is no such necessity. As such, while we might still have permission from God to eat meat, this still leaves us the option to chose not to do so.
The second argument that Aquinas considers is based on the assumption that murder is sinful because it deprives a man of his life. Since animals and plants are also alive, it would seem that it would also be sinful to kill them.
Aquinas responds to this by using what certainly appears to be views taken from Aristotle. To be specific, he claims that animals and plants lack reason and are driven by mere natural impulses. Because of this, they are “naturally enslaved” and exist for our use.
This is, of course, another version of the “we are better than them so we can eat them” argument. If we take this principle literally and apply it consistently, then it would seem that rational humans could thus consume humans who are not rational (such as infants). After all, as Augustine argued, a human infant would seem to be on par with a mere animal.
Various people have also argued that some animals do possess reason (such as elephants, primates and whales). If so, killing them would count as murder under Aquinas’s view of the matter.
Aquinas’s third argument is purely theological. He notes that divine law requires special punishments only for sins. There is a special punishment for a man who kills another man’s ox or sheep, so it would seem that killing animals would be sinful.
His reply is a very easy one-the sin being committed is not a sin of murder but of theft. This is because the killer is depriving another man of his property. This, of course, does make it sinful (and immoral given Aquinas’s moral theory) to kill animals that people own (such as pets).
My main thought on these arguments is that while they do argue that eating meat (and plants) is morally and theologically acceptable, they do not show that we must eat meat. After all, even if it is agreed that we can eat meat, it does not follow that we are required to do so. In light of the concerns raised by Aquinas and Augustine, it would seem reasonable and ethical to avoid eating meat except when we must do so to survive.