The following is from a talk Peter Singer gave at the Ideas Festival in Bristol, 2009

We start with the before-Darwin perceptions that we have because I think its important to look at what people were saying about animals to understand the difference that Darwin's thought made. Obviously one of the classic texts is the pre-Darwinian account of the origins of the various animals in the classic verse of Genesis. In this, human beings are special in that they said to be made in the image of God. And they have dominion over other things God created:

let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.

Genesis 1:26

That's the view that for millennia people were taught as the right view. It was not the only view around but other views were somewhat similar; for example, here we have Aristotle, not in the Hebrew tradition, but coming up nevertheless with a somewhat similar idea of other species existing for out sake. In Aristotle's view, the universe was so constructed that the less rational exist to server the interests of the more rational. Plants are the lowest on this scale with the vegetative soul, and they exist to serve animals, which are more rational, but animals in turn exist for the sake of human beings, the most rational of all. For example:

We may infer that, after the birth of animals, plants exist for their sake, and that the other animals exist for the sake of man, the tame for use and food, the wild, if not all at least the greater part of them, for food, and for the provision of clothing and various instruments. Now if nature makes nothing incomplete, and nothing in vain, the inference must be that she has made all animals for the sake of man.

Aristotle
Politics, Book 1, Part VIII

This view was also highly influential and, as you can imagine, it was not too difficult to combine it with the Genesis idea, as we'll see in a moment.

One thing that is left out of this particular quote but that you get elsewhere in Aristotle is that even within our own species, he thought the less rational exists for the more rational, which provided a fine justification for slavery, given the additional premise that the Barbarians, i.e. those who are not Greek, are less rational than the Greeks. So, there was a whole teleological ordering of the universe in terms of rationality.

If we move into the Christian era, we find in the pre-eminent Christian philosopher Thomas Aquinas, who had the greatest influence on the teachings of the Roman Catholic Church in his era, so much so that Thomism--his philosophy--became a kind of semi-official philosophy of the church. He appealed both to the Aristotelian idea about rationality and also to the idea represented in the verse of Genesis about man's dominion, and he actually went so far as to say that it doesn't matter how we behave to animals because of that grant of dominion. He also said we don't owe animals even charity. So, for Aquinas, we don't have obligations to animals because God gave us dominion over them, and we don't even have obligations of charity to them because they don't share with us the fellowship of eternal life. The difference, then, between humans and animals in the Christian view was our being made in the image of God, having dominion over animals, and having eternal souls--we were thought destined to have everlasting life and animals were not.

In Aquinas' view, the only reason why you should not be cruel to animals was the indirect argument that if you are cruel to animals, you may develop a cruel disposition and become cruel to humans as well. That argument may have a certain validity to it. Certainly there are cases of people who commit horrific crimes that began with cruelty to animals. But of course Aquinas's reasoning completely leaves out the animals themselves, and leaves out any concern for their interests. That's what the real problem is with Aquinas and his view, I think, here.

Let's look also at a much later philosopher closer to Darwin's own time, the great German philosopher Immanuel Kant--still regarded as one of the greatest philosophers of all time. He took a somewhat similar view on animals. We owe no direct duties to animals, Kant says,

Animals are not self-conscious and are there merely as the means to an end. That end is man

“Duties to Animals and Spirits” in Lectures on Ethics (c. 1780)

That was Kant's view of animals, clearly following still within that Christian tradition--not really thinking very independently of it, although the reference to self-consciousness is perhaps something a little different.

Interestingly, what Kant never discussed, despite the fact that his whole philosophy--about who you have duties to, who are ends in themselves, and who were merely a means to an end--depends on self-consciousness or rationality or autonomy (there are different terms for it). But he never even asks the question of what we do, say, about human beings who are not self-conscious. Because obviously there are some human beings like that-- none of us are born self-conscious for one thing. No new born infant is self-conscious--they're conscious, they can feel pain, but they don't have self-awareness. That only develops at some stage during the first months of life. And of course there are also some humans who, through serious intellectual disability or brain damage, are also not self-conscious. Kant doesn't address the question of whether his philosophy means that they too are just means to an end and we have no direct duties to them. It would seem to follow that if he had said that of course it would have aroused a lot more opposition.

So, that's essentially the pre-Darwin picture of where humans stand in relation to animals and what their moral obligations are. But not every philosopher held such views before Darwin. I've focused on those in the mainstream tradition, but already before Darwin in the English utilitarian tradition, started by Jeremy Bentham, you do get a concern for animals because Bentham and the English utilitarians were concerned about pain and pleasure. That was for them the mark of what was of value. And it was obvious to them that animals are capable of feeling pain.

Bentham has quite a remarkable footnote in a work written not too different in time from when Kant was writing his--at the end of the 18th century (though not published until the end of the 19th century)--where he points out that the French have liberated African blacks from the bonds of slavery. At that stage the abolition of slavery had not happened in Britain. Bentham talks about things that demarcate animals says that soon people will realize that things like anatomical details are no reason for abandoning a sentiet being to the caprice of a tormentor:

Other animals, which, on account of their interests having been neglected by the insensibility of the ancient jurists, stand degraded into the class of things. ... The day has been, I grieve it to say in many places it is not yet past, in which the greater part of the species, under the denomination of slaves, have been treated ... upon the same footing as ... animals are still. The day may come, when the rest of the animal creation may acquire those rights which never could have been withholden from them but by the hand of tyranny. The French have already discovered that the blackness of skin is no reason why a human being should be abandoned without redress to the caprice of a tormentor. It may come one day to be recognized, that the number of legs, the villosity of the skin, or the termination of the os sacrum, are reasons equally insufficient for abandoning a sensitive being to the same fate. What else is it that should trace the insuperable line? Is it the faculty of reason, or perhaps, the faculty for discourse?...the question is not, Can they reason? nor, Can they talk? but, Can they suffer? Why should the law refuse its protection to any sensitive being?... The time will come when humanity will extend its mantle over everything which breathes... "

Jeremy Bentham (1748 - 1832)
Introduction to the Principles of Morals and Legislation

It's only in a footnote published in the introduction of The Principles of Morals in Legislation, but it is enlightening. It is interesting that that thought was at least possible before Darwin. But it was certainly not something that had gone into the mainstream at that stage.

Now we turn to Darwin himself, and rather than the familiar photos of the elderly Darwin, I thought I'd give you a photo of Darwin as a younger man.

The portrait was painted around the time that he was writing in his notebooks this remark.

Man in his arrogance thinks himself a great work, worthy of the interposition of a deity, more humble and I believe true to consider him created from animals

Notebook II, written in 1838

Darwin did not publish this at the time. It was 20 years before he would publish The Origin of Species. And even The Origin of Species does really address the question of where human beings came from. It's a work about evolution of species, but it doesn't deal with the human issue. Darwin himself remarked privately that if he had done so, it would have brought down a lot of opposition on him.

It was not until 1871, in fact, that he published The Descent of Man. So the notebook statement is more than 30 years before Darwin actual dares to express such a view in public. But the notebook shows he's already thinking along these lines in 1938--thinking that the Genesis view is actually a kind of arrogant self-proclamation of our special moral status and that rather we have a humbler origin which links us to animals.

Darwin was very interested in that link--of course he had to be in terms of evolution. But interestingly he did not just limit it to claims of a our physical descent and the anatomical similarities between us and animals, but considered it also in terms of our mental capacity. Here is Darwin finally from The Descent of Man in 1871 pointing out that the lower animals, like man, manifestly feel pleasure and pain, happiness and misery:

Happiness is never better exhibited than by young animals, such as puppies, kittens, lambs, etc., when playing together, like our own children

So he sees the parallel, he sees the fact of pleasure and pain, happiness and misery in animals, and he is not afraid to draw attention to that.

It is a significant claim that he's making because even much more recently we went through a period when scientists were reluctant to make those sorts of claims. Psychology went through a period of behaviorism in the 1950s and still into the 1960s when it was considered unscientific to impute mental states to animals because we could not observe these states. So if you gave an electric shock to a rat, as was commonly done by these psychologists, you didn't say the rat showed pain or the rat felt pain or it hurt the rat, you said something like, the rat exhibited aversive behavior, meaning the rat tried to escape from the electric shock. But that's a behavioral statement, not a mental one. Darwin was prepared to make the mental statements and subsequently scientists have recognized that it was quite absurd to deny mental behavior. Numerous behavioral animal studies now are based on trying to understand the mental states of animals.

Here's another statement from Darwin which goes even further and points to the continuum between humans and the higher animals. This is in a paragraph that occurs at the end of Chapter 4 of The Descent of Man and summarizing what he said in the preceding two chapters. Darwin of course acknowledged that there is a great difference between humans and animals, but he said that is is one of degree, not of kind. So just as in tracing the anatomical parallels he traces parallels in terms of mental capacities:

We have seen that the senses and intuitions, the various emotions and faculties, such as love, memory, attention and curiosity, imitation, reason, etc., of which man boasts, may be found in an incipient, or even sometimes in a well-developed condition, in the lower animals.

Darwin is not afraid to make these significant attributes and that it's not just about pleasure and pain. There's a lot more going on in the minds of animals and Darwin is prepared to recognize and state that in print. He even wrote another little book after this called the Expression of the Emotions of Man and Animals, which is a fascinating early account of animal observations and behavior, a compilation of observations that expressly deals with these kinds of parallels.

Here's an interesting point a little different to what I've talked about but that shows how important the existence of animal suffering was for Darwin. This is from Darwin's autobiography, which he wrote late in life and which was published posthumously. In his early life Darwin had been a Christian, even on the voyage of the Beagle he argued with the captain about Christianity, defending Christianity, and even later talked about a creator god. But in his autobiography he actually produces an argument against the idea that the universe was created by an omnipotent and omniscient being. It relates to the familiar argument about the problem of evil, which many religious people have grappled with and tried to answer, and which many non-religious people have used as a reason for not believing in an omniscient and benevolent god--a god with all the traditional Christian attributes. The standard reply to the argument is that God gave humans freewill to improve themselves morally, even though freewill may result in evil and suffering because, ultimately, freewill is a greater benefit. But for Darwin, the crux of this argument centres on animal suffering. He points out that suffering in the universe is not only suffering of humans or suffering caused by humans, but in fact involves the suffering of non-human sentient beings, and this is on scale much greater than the suffering of humans because there's so many more of them. The basic question behind his argument against the traditional idea of God, therefore, is, Why is there this animal suffering? How would a God created this suffering, which goes on without human intervention and certainly doesn't serve the moral improvement of either humans or animals. For Darwin, this problem led to an objection to the existence of the traditional God. It thus shows how significant the suffering of animals was in Darwin's view of the world.

Let me now move to what in a post-Darwinian world. We no longer believe that we have a right to use animals because God has given them to us and we no longer believe, as Aristotle did, that the less rational exist to serve the more rational. What ethics, then, should we develop about how we should treat animals? Well, the first point is one that basically Darwin was saying: we have to accept that animals are conscious beings. They are sentient beings and that means they can feel things, they can suffer, and they have a subjective point of view of the world. There's something that we can imagine perhaps of what it's like to be an animal in pain or an animal enjoying fun. And the reason for this is essentially the second thing Darwin pointed out, that we have similarities with animals. We know now in much more detail than he did about their nervous systems, about their physiology, about even the biochemistry of feeling pain in humans and animals, and these aspects are quite similar; that is, between us and birds and mammals--vertebrates more generally. Animals behave in similar ways in circumstances where they would be feeling pain. And thirdly, what Darwin showed is that they have a common origin. So it's not that God separately created these other beings with copies of our mechanisms without putting in any consciousness. We know that we have a common history, and it doesn't seem very likely that things that evolved for a certain purpose in us did not have similar sorts of evolution in nonhuman animals. So, if we evolved to feel pain it's very probably that animals did as well.

That's the first premise you need. Now this may not apply to everything that is in zoological terms an animal. Imagine a scale of animal consciousness. You would have the highest level of confidence in consciousness at the top and the lowest level of confidence at the bottom, and so you then have to make a decision where you draw the line. I think it's quite clear that mammals and birds are conscious; it's pretty clear that vertebrates are conscious. I think some invertebrates must be conscious too: if you look at the things an octopus can do, it's hard to imagine it can do those things without consciousness. By the way, an octopus, for those who don't know, is probably the most intelligent invertebrate. There's a lovely video somewhere on YouTube of an octopus that is given a screw top jar with a crab in it. It's a crab eating octopus. Of course, octopus never evolved to deal with screw-top glass jars, but this one doesn't take very long to learn how to unscrew the jar and get the crab out. I think it has to be conscious to do that.

Also, there was just recently a report in one of the newspapers I saw a couple of days ago about crustaceans feeling pain. Every now and then you get one of these reports, and this report indicated more parallels than perhaps we had realized before in what goes on in Crustacea. But still it's more of a grey area, I think, because the centers of consciousness are different. There isn't such a close anatomical and physiological parallel. And when you get to claims in oysters, which can't really move away from pain, as these other beings we've been talking about can, it's probably a lot more questionable whether they can feel pain. The same is true with insects.

But I'm going to focus on those animals where I think it's clear, so when I talk about animals from now on, let's say I'm talking about vertebrates and cephalopods, like the octopus perhaps, while the others are maybe more doubtful.

So what's the mainstream view today in this post-Darwinian world? It's not of course Aquinas or Aristotle's view or even Kant's. Most people think we have a direct reason not to be cruel to animals, and that's because the animals feel pain and it's bad for them. So we have moved from the indirect duty view to the direct duty view, and that is certainly progress. Nevertheless, it's really still a view about kindness and cruelty, and kindness and cruelty are very often defined in ways that mean gratuitous cruelty. Consequently, if something serves what is considered to be a legitimate human purpose, it is less likely to be regarded as cruel, even if it does cause distress or suffering. I want to suggest that we should move beyond this mentality--that kindness is good and cruelty is bad--and actually face the issue of how much consideration we should give to nonhuman animals.

Non-human animals have interests; that just follows from the fact that they are conscious, they can feel pain, they have interests. At a minimum, they have an interest in not experiencing pain. But given what Darwin said, they also have an interest in being happy, in so far as they are capable of their own form of happiness. They have in interest in not being miserable, and you can be miserable even if you are not actually in physical pain. For example, if you are a pig confined in a factory farm on bare concrete with nothing to do all day except eat when food is put in front of you, you can be completely bored and frustrated, and you can be miserable even if you are not in physical pain. So animals have interests, and the question I ask here is, well, Why should we give less consideration to the interests of a being because it's not a member of our species. I don't there is a justification for doing that. I think we should look at the interests for what they are rather than what species a being belongs to.

Some people say, look, I have obligations to members of my species that I don't have to beings that are not members of my species. One way of looking at this would be to think about one of those nice friendly aliens that we get in science fiction, in movies or stories, something like ET the extraterrestrial--someone who is clearly of a different species from us but who has feelings somewhat similar to us--it gets lonely, gets homesick, cares for company, wants to respected and not humiliated, and all the rest of it--and then imagine that somebody says, well, let's kill the alien and dissect him to see what he's like inside. Now I think we would reject this idea if we got to know this alien. We would say you can't do that, and if they simply said well he's not a member of our species, and we only have obligations to the members of our species, you wouldn't think that is a very good argument. You would recognize that it's not really relevant what species he belongs to, what's relevant is that he has interests, that he can feel things, that he has wants and desires, and if you kill him, you are going to end all of that.

I think we should not take species in itself into account in trying to decide how much consideration to give interests, which means we should apply the principle we apply in our own species so that the equal consideration of interests also applies to members of other species. In other words, we reject what I called speciesism, or the treating of animals differently from humans simply because they are not members of our species.

I do think that in speciesism there is some parallel between racism and sexism. Both of those are ideologies that developed because a dominant group wanted to give itself privileges, wanted to make use of others in various ways, including slavery--obviously here in Bristol we've got a history of the usefulness to the city in the 18th century of slavery and the slave trade. So the dominant group develops an ideology of racism that justifies this and we're familiar with the same thing in the case of sexism. We reject these ideologies and I think we should reject speciesism as yet another ideology by which we give ourselves justification and justify our power and domination over other species. Which is not to say of course that the parallel is exact. Obviously the differences between humans and other species are greater than the differences between different human beings, and I'll talk about that in a moment. But speciesism is an ideology that functions in a similar way to racism and sexism.

One of the major ways in which speciesism functions is to support the eating of meat. Here's a quote which is not from a radical animal rights activist but from a professor of animal science at Oregon State University in the United States, who says that one of the reasons why we continue to eat meat is that a lot people, most people, don't really know how their meat is raised and processed. If they did, he is saying, it would be damaging to the meat industry.

One of the best things modern animal agriculture has going for it is that most people... haven’t a clue how animals are raised and processed... If most urban meat-eaters were to visit an industrial broiler house, to see how the birds are raised, and could see the birds being ‘harvested’ and then being ‘processed’ in a poultry processing plant, some, perhaps many of them, would swear off eating chicken and perhaps all meat. For modern animal agriculture, the less the consumer knows about what’s happening before the meat hits the plate, the better.

Peter Cheeke, PhD
Oregon State University Professor of Animal Agriculture
Contemporary Issues in Animal Agriculture, 2004 textbook

Probably in this country you're a little better informed, and I'm sure you're all very well informed, but the British public may well be better informed than the American public. I know that Jamie Oliver has been doing his part here in informing television viewers about how their food is produced and I certainly applaud that. I don't think that has been shown on American television, or if it has it would on some small cable channel rather than on some main stream channel. But you probably already know most of what follows, so I won't spend time with it.

It's things like this: the mass production of chicken, for instance, that comes under the application of that mainstream view I mentioned. People are still saying, well, this is not cruel, it's something we need to do to produce food--which of course is not in itself true either because we have to feed these chickens on grain or soybeans, or something of that sort, and we could eat the planet foods directly and get a greater quantity of food, greater food value, then by processing them through the chickens and then eating the chickens. So it's a wasteful form of production in fact. So people justify such processes as serving a purpose that means that the kindness-cruelty view generally doesn't apply to it. However, people are starting to see this differently now and starting to see this as indeed a form of cruelty, as I think they should.

And here we have the battery egg system, which is in the process now of being phased out in the European Union. I certainly hope there is no backing away from that goal. I think it's 2012, though I could be wrong, that it's supposed to be phased out, so not too far away. A very welcome outcome. Britain is ahead of the United States here, though California voted in November on an initiative to allow all farm animals room to stretch their limbs without touching another animal or the sides of their enclosures. That of course completely rules out this kind of way of keeping hens, and that's the biggest victory for the American animal movement, I think, in decades. But as I say, in the European Union, you are ahead of the United States on these things.

This is what the battery hen looks like after being in a battery cage for a year or so laying her eggs. She's lost almost all her feathers, and of course she never does normally get on grass, but this one was freed by an animal organization. And it's amazing how quickly they learn to do the things, or have the instincts to do the things, that they can't do in a battery cage, like stretch their wings, lay an egg in a nest, chase insects in the grass, dust bath--all of those sorts of things are still there in their behavior.

Here is a cattle feed lot in the United States. Vast, enormously wasteful both for grain, because cattle are even worse converters of grain than chickens, and essentially a methane producing factory. Methane is an extremely potent greenhouse gas.

OK, so here's a quick argument for why I think all of this is wrong, which simply starts from the premise that it's wrong to cause pain without a good enough reason, rejecting of course the speciesist claim that you can do it to animals. Animals suffer, we've seen that; we could nourish ourselves in other ways, as I've said. Our enjoying of the way meat tastes is not enough reason to justify the amount of suffering that animals are made to endure. So, this is where the argument really departs from the mainstream kindness-cruelty view, which would say, well, it's not cruel, we're not doing it cruelly, we're just producing the animals in a way that produces meat cheaply and we enjoy the taste of it. What I'm saying is that if we accept the principle of equal consideration of interests, which we should accept once we reject the pre-Darwinian views of the universe, then the mainstream view is not good enough. In other words, if we give equal consideration, we can't say that out enjoyment of the way meat tastes outweighs the suffering animals are made to endure on factory farms. The conclusion is that at least we should stop eating the products of factory farms. That seems to me the clearest and most obvious consequence. And also the most important one for the animal movement.

I've focused on factory farms because that is where, I think, the largest part of the vast universe of suffering that we inflict on animals is to be found. And that's not to say there isn't significant suffering in, for instance, the use of animals in research, but the numbers are just so much vaster on farms. I don't actually have current figures for the UK in terms of farm animals, but for the United States the number of animals used in experiments is probably somewhere between 25 and 30 million--roughly the population of the state of California--but the number of animals killed for food, virtually all factory farm animals, is 10 billion--more than one and a half times the population of the world. It's a vast difference in numbers and the difference is probably going to be somewhat similar in scale in this country as well. That's why I say this is the issue that I think we ought to focus on because it's where most of the suffering occurs.

I want to add something to what I said before, which is that there are differences among species and equal consideration of interests does not mean that all animals have the same interests, and it does mean that we can treat animals and humans in the same way. This would be one of the differences between racism and speciesism.

For example, this is a photograph of some cattle that are being raised on an organic pasture based farm. These animals are confined to this farm obviously. They are not free to wander outside of it, but I would say their interests are quite well satisfied on this farm in that they are allowed to stay with their mothers here. They graze in a social group; they have what they need. They don't really have the need to travel. When I show this to my students and say, well, how would you feel about being confined to the beautiful campus of Princeton University--they have everything that they need, right, they can get feed there; they have student dining services; they can get education; they can listen to things; they have shelter; they have company--all of their basic needs. But of course it's not enough for them. New York city is just an hour or so up the train line, and they wouldn't want to be deprived of the opportunity to go there sometimes. So, we do have different interests. That's got to be recognized. We don't have to treat animals the same, but we do have to consider their interests.

The most serious objection to arguments for vegetarianism based an equal consideration of interests comes from the British philosopher Roger Scruten, whom some of you may know because he writes or used to write columns for the Times. He says that while he is certainly opposed to factory farming and would agree with my kind of argument up to this point, he thinks that the death of an animal is not the same as the death of a human because the idea of being cut short before your time doesn't really apply. His argument is that if a human being is killed at a relatively early age, we feel it's a tragedy because they were not able to achieve what they could have achieved. They could have gone on to various things perhaps, depending when they were killed I guess--perhaps they had planned to do those things, perhaps they had worked hard for them, perhaps they had studied for a career in engineering or medicine or philosophy or whatever it might be--but then they were killed before they could fulfil their hopes and ambitions. So, that's a tragedy, whereas cattle, Scruten says, don't have those sorts of hopes and ambitions for the future. Their going to die at some time and their death earlier or later is not a tragedy in the same way.

And I do think it has to be admitted he has a point. Whether it's enough of a point to carry the day is another question, but it's true that we as humans, with the capacity to see ourselves as existing over time and making plans for the future, have more to lose if we are killed prematurely than animals that exist more in a moment to moment state. However, those animals will have to lose the rest of what might be a good life. If it's going to be a life with more happiness than misery in it, they lose that balance of happiness. They don't additionally lose the thwarting of their plans, and all they were doing up to the point when they were killed to try and achieve those plans. So I think it is reasonable to say that we do have a greater interest in continued life than nonhuman animals have, which is not to say, however, that they have no interest in a continued life.

So what could you say about justifying some animal use while accepting Darwin's view of animals and while accepting the sort of ethic I put forward? I think you have to say that pain is equally bad no matter what the species of being that experiences it. But you can also say that death is a greater or lessor loss depending on factors like awareness of one's existence over time, quality of life, and so on. And then you have this question of whether you could justify the use and killing of animals, if they had good lives throughout their life.

Let's say you have a farm like the one I showed you, where animals live a fairly natural life--we assume it's sustainable, although, as I said, because of cattle and the amount of methane they produce, sustainable farming with cattle is difficult to defend--and if they are painlessly killed, and they don't have to go through the transport to slaughter and that slaughter is done in a way that is calm for them, I think you could argue it is defensible, at least if it satisfies some reasonably significant human need, and it could do that if it were a way of obtaining food from pasture that could not be used for crops, and which therefore adds to the amount of food available for us in a sustainable way. I think that there are still problems with this scenario, so it's not one that I would myself end up endorsing: for one thing, it makes things very complicated to try and even find products that are produced in that way. There is always the danger too that because you're still thinking of animals as something we can use for our purposes that standards are going to slip and you're going to fall back to something less desirable.

To those who differ with me over that, I think that's an area where we can have a reasonable disagreement, and as long as people are clear about what is indefensible--the factory kind of raising of animals, the raising of animals in less desirable conditions than the ones I've talked about--that would be progress. That's the biggest battle to be fought and won now, and if we do achieve that we can then consider how much further we want to go in terms of where we think a post-Darwinian view based on equal consideration for animals leads us to.