As a way of getting my blogging going, I thought I’d start a series of posts on some teachings of Thomas Aquinas.  I think this will be interesting (at least to me) because Thomas covers so much material in easy-to-digest portions and because his Summa is available online.  So today, let’s start—for no specific reason—with his argument about killing plants and animals.

Thomas says that it is not a sin to kill plants and animals to use as food.  His basic argument is that “there is no sin in using a thing for the purpose for which it is.”  Since the purpose of plants and animals, which are both imperfect in comparison with human beings, is to be useful to human beings, a human being does no wrong in killing either plant or animal if he needs to use either of them.  Thomas thinks that the purpose of plants and animals is to be useful to human beings because “the order of things is such that the imperfect are for the perfect.”

The reasoning about the order of things in this particular case is based on Aristotle’s conception of the different kinds of soul.  I suppose if someone thinks Aristotle’s wrong about the soul, they won’t find Thomas’s arguments persuasive.

Thomas also has an argument from the Bible, namely, Genesis 1:29-30 and Genesis 9:3.  The first passage only allows eating plants.  The second allows for the eating of animals.  Some have argued that since the latter allowance is made only after the Fall, those who live after the Resurrection should no longer kill animals.  But there is no suggestion in Thomas that the allowance in Genesis 9:3 has been taken away.

It is interesting, from our point of view, that Thomas does not even mention the issue of animal pain.  Today, however, that consideration is a prominent source of arguments against the morality of killing animals.

It is also interesting, from our point of view, that Thomas does think that the question of killing plants needs to be addressed.  This is probably because from our point of view the question of killing animals is addressed as a matter of not causing pain.  Since plants do not experience pain, then we need not worry about killing them.

Thomas’s interest, however, is not in not causing pain but in taking life.  Life, as a fundamental kind of good, should always be respected.  It is this concern for life that makes the issue of killing plants a live one, one that Thomas has to address in his ethics.

There is also the point that the killing of plants and animals can be moral only if they are being used appropriately.  I think this would rule out hunting for sport (unless sport can be considered necessary or sufficiently momentous in human excellence), but it would not rule out using animals for medical testing, though it would rule out using animals for testing cosmetics.

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Posted by Gary Hartenburg


  1. Thomas Says: Killing Plants and Animals | Mere Orthodoxy

    This comment was originally posted on Twitter


  2. This is an issue I’ve been dealing with quite a bit recently. I agree that humans are in a higher order than plants and animals and can be properly used (stewarded?) by humans. And yet at the same time we have the issue that life is sacred and, as you pointed out, we were not created to nor in the end will we need to consume animals. In fact, though perhaps other cultures and other times have found consumption of animals to be necessary, it is no longer, at least in more developed ocuntries, necessary to eat animals to survive or even thrive nutriotionally. (as a side, veganism is another case: it is almost always necessary to supplement one of the B vitamins). So between the fact that it doesn’t seem eating animals is necessary, and the fact that Christ has brought the Kingdom and is redeeming all things, then I am left with question, how can I logically and ethically continue to eat meat? The only reasons I can think of are because it tastes good (which doesn’t seem sufficient), or because it helps me to recognize in a very real way the brokenness of the world and it’s need of redemption. Is there something I’m missing?

    As an interesting side note, there is actually a dietary lifestyle that takes the sacredness of life to the max: they only eat plant parts that do not require the life of the plant to be taken for consumption. I think this would mean mainly fruits, nuts, leaves and the like.


  3. odlaram7,

    In light of your comments, what do you think about Christ multiplying fish for consumption and eating fish himself. If it is good enough for God, why are you in a quandry?


    Can you please elaborate on what you mean by “hunting for sport”? Is this killing for no other reason than to kill without consuming the animal? Can a man who doesn’t “need” to hunt for food hunt game as long as he consumes that game or at least sees that the meat goes to someone who will? Do you leave it to each person to judge what is “appropriately”? That would be good Protestant tradition anyway. And what could “sufficiently momentous in human excellence” possibly mean? ;)



  4. I.J.,

    That is certainly a good question. The easiest answer would be to put it under the category of “though other cultures and other times have found consumption of animals to be necessary, it is no longer, at least in more developed ocuntries, necessary to eat animals to survive or even thrive nutriotionally.” Another answer would be to distinguish between fish and other animals like some vegeterians do, though I’m not fully sure I see a good support for that, besides which if Jesus ate like a Jew, he ate meat, too. And of course there are some strange interpretations I’ve read where people say those passages of Jesus spreading around the fish were merely symbolic. Am I making anyone yawn yet? :)

    In other words, I don’t really have a good answer. Obviously, killing animals (for any reason, really) is not the way things were meant to be. It even appears that this was the case for a bit after the fall. So the question is, if Jesus brought the Kingdom, how much are we to live in it and how much are we to live with the provisions of this world. (and I’m not quite a Protestant which may make our thoughts about this differ)

    This might be opening a can of worms, but I wonder if this is similar to divorce. I’ve often heard it described that though divorce is by nature bad, that it is in a very few cases permitted. Could killing animals be something that is always bad, but for whatever reason after the Ark, was permitted? St. Paul said that all things are lawful but not all things are beneficial. Perhaps this falls into this category?

    (This is more than simply a theological exercise to me. It’s something I really wish I had an answer to, and it doesn’t help that I like meat. :) )


  5. Hunting for sport = hunting for the enjoyment of the activity itself and not because one needs to eat the quarry. I suppose that one could hunt for things one doesn’t need without hunting for sport if one doesn’t hunt for the enjoyment of the activity. (Suppose one hunts out of habit or vice without care for whether one enjoys the activity.) So hunting for sport and hunting for need don’t necessarily exhaust the kinds of hunting.

    Sufficiently momentous in human excellence = a need. I said that hunting for sport is not the same as hunting out of need. But if humans are to be all they can be (with apologies to the US Army), then maybe they need to excel at hunting. Thus, there’s a sense in which hunting for sport might be a need, not a need in the survival sense of need but in the sense of being the best one can be as a human being.


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