Towards a Christian Ethic of Animals
Richard Wade


The purpose of this article is to make a contribution to the discussion on animal ethics. It is my contention that there is no need to invent, as it were, a Christian animal ethic, because respect for animals is found within the Christian tradition. In this article, I develop a Christian ethic of animals as an extension of a Roman Catholic ethical tradition, which has its origins in Aquinas’ incorporation of insights from the Roman jurist, Ulpian.

In contemporary society there has been a cultural shift in our understanding and valuing of animals. This cultural shift in thinking leads us to discuss the traditional relationship of humans to animals. Traditionally we have used animals for food, work, clothes, transport, experimentation and recreation. Frequently, the Scriptures are cited in support of the view that animals are primarily for human benefit.

At the popular level, many interpreted the ‘dominion over animals’ text (Gen 1: 26) as giving humans power over animals, with blanket approval to use animals in any way that benefited humans. However, a scholarly interpretation of the Scriptures and a re-examination of our beliefs indicate it is our responsibility to be God-like in our treatment of animals. This relationship of responsibility to God for animals is embodied in the virtues of justice, wisdom and compassion (Wis 9: 2-4).

The manner in which humans relate to animals and take constructive responsibility for them is a fundamental dimension of our relationship with God. In contemporary society, there is a growing awareness of animal rights and indeed of human duties to the environment as a whole. This development has challenged Christian ethicists to reflect on an area of contemporary Roman Catholic theological ethics that has largely been ignored.

Natural Law Ethics

A way forward in developing an ethic of animals is the natural law tradition, which not only has a long history and wide appeal, but also has a close association with Christian ethics. The philosophical natural law tradition dates back to Greek philosophers such as Aristotle (384-322 BC) and also Roman jurists such as Ulpian (c. AD 170-228). In terms of Christian ethics this tradition is found in the works of St Augustine (AD 354-430) and in particular St Thomas Aquinas (AD 1225-1274). It has influenced Christian ethics ever since.

As a general description, natural law is about fulfilling one’s nature. Animals do this by instinct but humans have to make decisions about how best to live fully human lives. Ulpian defines natural law as:

that which nature has taught to all animals; for it is not a law specific to mankind but is common to all animals – land animals, sea animals and birds as well. Out of this comes the union of man and woman which we call marriage, and the procreation of children, and their rearing. So we can see that the other animals, wild beasts included, are rightly understood to be acquainted with this law.

This fact – that the natural law is expressed in terms of animal well-being – opens up the possibility of an animal ethic within the existing Christian ethical tradition. For this same thinking is found in Thomas Aquinas, in his account of natural law as the fulfilment of our rational animal tendencies. Aquinas incorporated Ulpian’s definition of natural law (‘that which nature has taught all animals’) into his ethical thinking on natural law (jus naturale). Here is the ‘gateway’ through which Ulpian’s insights became embodied within the Catholic tradition.

In a key discussion of the natural law Aquinas indicates that there are three stages in the natural tendencies of the human person:

There is in man, first, a tendency towards the good of the nature he has in common with all substances; each has an appetite to preserve its own natural being. Natural law here plays a corresponding part, and is engaged at this stage to maintain and defend the elementary requirements of human life. Secondly, there is in man a bent toward things which accord with his nature considered more specifically, that is, in terms of what he has in common with other animals; correspondingly those matters are said to be of natural law which nature teaches all animals, for instance, the coupling of male and female, the bringing up of young and so forth. Thirdly, there is in man an appetite for the good of his nature as rational and this is proper to him ... whatever this involves is a matter of natural law.

It should be noted that for Aquinas rational animality also involves the fulfilment of our biological tendencies. So natural law in Aquinas might also be thought to involve plants. In one sense this is true but from an ethical perspective it would seem that plants are unlikely to be morally considerable for their own sakes since they cannot enjoy fulfilling their natural inclinations or being frustrated in the non fulfilment of their natural inclinations. Aquinas’ ethics is concerned with the achievement of happiness and because happiness involves a subjective awareness of being fulfilled, this would seem to exclude plants. However, common sense maintains that animals do enjoy the fulfilment of their inclinations at their particular level of being. For example, animals have social, psychological and biological inclinations (sex, procreation, rearing of offspring, food, water, shelter, company, play, and so on). In so far as animals do enjoy these inclinations it would seem that th ey should be included in natural law under the ethical sense of the term. That is, animals have their own happiness/contentment in relation to their particular nature.

In discussions of the natural law, the Latin word jus is often translated ‘law’. However, in classic Latin usage jus means what is right. Following this line of reasoning, it seems to me that Ulpian is defining natural law in terms of its ethical sense. Violation of the natural instinct/inclinations of animals (for example, the infliction of pain and abuse, deprivation of water, food, space to run free, and so forth) is against the interests they require to have their natures fulfilled. Since it frustrates the animal, such behaviour is not naturally ‘right’.

It is unethical because it causes animals to suffer the loss of goods they should by nature enjoy. In this sense the ancient Roman jus naturale, as defined by Ulpian, would appear to defend the natural right of animals. It would require, for example, that they be given water or at least not kept from having access to it; it would exclude putting a fence between the cow and the bull when the cow is in heat. Failure to respect the prima facie interests of animals based upon their nature is to deny them natural justice. This seems to be the correct interpretation of Ulpian.

Intrinsic value

Like everything else, animals have intrinsic value. However, in contrast to other beings, animals also have the capacity to enjoy living. At the level of their being it matters to them whether or not their lives go well or badly. Hence, they are also morally considerable. They have prima facie moral claims on humans to behave appropriately towards them. Cows and other animals, for example, can enjoy things (chewing the cud) in their own right for themselves. This can be maintained even if we admit that the sense in which non-rational animals appreciate living is imperfect as compared to human beings. If they enjoy living, they do not do so reflectively or self-consciously. So, although objectively these animals are morally considerable, at their own particular level their capacity for enjoyment differs from that of human beings.

In line with this tradition, the welfare interests of animals make moral claims on us compassionately and wisely to do the right thing by their nature/teleology/purposes. Claims to food and water, freedom from harm and so forth are not unlike the notion of rights claimed for human beings. However, given animals’ imperfect appreciation of living, it seems that none of their claims could ever be absolute. The jus naturale as defined by Ulpian and incorporated into Aquinas’ exposition of natural law is, in the interpretation I am proposing, a duty to do what is ethically right with respect to the nature of the animal (the kind of being the animal is). The claims of animals thus generate in us a duty to care for their welfare.

But, since not all natures have equal value, such claims may be overridden to preserve a proportionate good. To save my life, for example, I can defend myself by wounding or killing an animal, even though the animal has its own natural right. And, of course, even if it could be maintained that pests (like mosquitoes) and viruses (HIV) might appreciate living in some very rudimentary way, the fact that they cause major harm to humans and other animals provides a proportionate reason for destroying them.

While we have prima facie duties to animals, we also have duties to human persons with a reasonable need.

When these duties and needs conflict, the challenge for Christian ethics is to ensure that we do not smuggle our prejudices and culturally conditioned assumptions about the moral status of animals into the argument. To rightly adjudicate between the competing interests of animals and humans will require the intellectual and moral virtue of prudence. For example, in the face of long waiting lists of people needing heart transplants and too few human donors, scientists are looking at new ways to use animals to save human life. One way is to genetically engineer the hearts of pigs for transplantation into humans. The question arises whether, given the circumstances, this is ethically acceptable.

A Reply to a Possible Objection

Some might object that, while recourse to Ulpian’s sense of natural law makes a nice historical note, he was, of course, unaware of the is-ought distinction of David Hume (1711-1776) and what G. E. Moore (1873-1958) termed the ‘naturalistic fallacy’. I would, however, defend my interpretation of Ulpian against those who might consider that I have committed the philosophical howler of ignoring the clear divide between facts and values, making the unjustified move from descriptive (factual) judgements to commendatory or evaluative (normative) judgements. In this instance, I have moved from describing the interests of animals based on their teleology/nature/purposes and their additional capacities for appreciating these ends to indicating moral obligations towards them. Objectors would claim that a bridging principle is needed to move from fact to obligation.

But Alasdair MacIntyre has shown that Hume’s is-ought distinction is not some timeless truth. Rather, it arose out of a revolutionary moral outlook (ably assisted by the new sciences of the seventeenth and eighteenth centuries) that rejected the Aristotelian tradition. The Aristotelian tradition did not draw a sharp distinction between fact and value. Its key concept was that humans and animals have a fundamental nature and essential purpose/telos.

MacIntyre points out that Hume’s reason for maintaining that facts and normative statements are opposed to each other is not because facts are objective while normative judgements are subjective and simply sentiment. Hume took this stance because he believed that it is our emotions and desires and not facts that motivate us to action.

Nevertheless, MacIntyre argues, Hume was mistaken to say that there is a sharp divide between fact and value. Underpinning the is/ought distinction is a particular ideology: the assumption that moral argument and all moral concepts do not involve functional/purposeful notions. As soon as the concept of essential purpose/function was rejected, it ceased to be convincing to consider moral judgements as statements of fact. A wedge was driven between the world ‘out there’ and the world of the human subject. The world became value neutral, static, mechanistic and purposeless. It was now up to the human subject to impose moral value on the physical and neutral world of fact. This type of attitude to the created world has been a contributing factor to the environmental crisis.

Using the example of a watch, MacIntyre shows how it is possible to move from description of the watch (is/facts) to commendatory or evaluative (ought) judgements about it. To say ‘this is a good watch’ is in fact to say that it has some particular function/purpose. If the purpose of a watch is to tell the time accurately, then a good watch ought to be accurate in telling the time. The initial move in ethics is not to embrace the is/ought distinction but to identify the telos of human life. Once the purposes of the human person are identified, then it is possible to state that ‘you ought to do such and such to satisfy your well being’.

Moral judgements, then, express what is considered to be teleologically appropriate behaviour for human persons in community. This is another way of talking about the natural law. Likewise, it is possible to indicate our obligations to animals once we have identified the distinctive dimensions of the animal’s telos. Respect for animals entails prima facie respect for the teleology pertaining to them. Roman law categorised animals as objects. Yet Ulpian, himself a Roman jurist, interpreted the natural law in terms of a duty to respect the requirements of the nature of animals. ...


As I have shown, respect for animals is long standing within the Christian tradition, although it has been somewhat neglected. The paradigm of duty as found within Ulpian’s definition of natural law and incorporated into the Catholic tradition by Aquinas challenges us to consider seriously all animal interests (sentient and non-sentient). This animal ethic ... respects human dignity and at the same time signposts an ethic that is respectful towards animals without suggesting that some animals are persons. If we work within the framework of Ulpian’s definition it is possible to rehabilitate an understanding of natural law in terms of animal claims and human duties. Animals are God’s creatures. The manner in which human beings relate to them and take responsibility for them is a fundamental dimension of human relationship with God. My interpretation of Ulpian’s natural law is one way to ground this human responsibility.

I would also suggest that the approach I have taken is one that blends with contemporary sensibilities and culture. It raises further ethical issues now being aired. For example, should human needs continue to override animal interests in areas such as medical experimentation, recreation, and food? The debate over a Christian ethics of animals is in its infancy, but our postmodern world demands that we encourage its growth.


This is an extract from an article in Pacifica, 13 (June 2000), the journal of the Melbourne College of Divinity. It appeared in the present slightly abridged form in the journal The Ark (Summer 2002 issue). Please see web-site Used with permission.