The logical morality of vegetarianism

August 23, 2008 at 6:37 pm (Articles) (, , , , , )

I’m often asked why I’m a vegetarian, and people are confused when I say that the answer is long and logical. I tend to just summarize it badly in one line: “because I would not be willing to kill an animal for my own gain”, but this doesn’t really explain why. Its not because I’m squeamish (though I am) – its because I want to be a moral person, and I see vegetarianism as a logical consequence of this. This is an opportunity to explain my reasoning in full, and I hope to engage in thoughtful dialogue with people who disagree.


The argument is long and contains a lot of logical steps, so I’ll summarise it first. I start by defining what I mean by “real” morality, as regarding morality as something to aspire to, rather than as a fundamentally selfish tool that keep society functioning. I consider who and what a moral system is supposed to apply to, and conclude that animals appear to reach a standard of intelligence and feeling to be included in the moral system. I explain why the appearance of feelings should be interpreted as real in the case of animals. I also argue that neither religion (the non-fundamental sort) nor physical differences should be a barrier for moral behaviour towards animals.

Animals therefore should have some moral protection, but morality is not an absolute thing. When conflict arises we have a right to stick up for our own interests. I discuss this in terms of the benefits that we gain and the costs involved to the other party. The benefits to us are of eating meat today are limited to pleasure, which may still be acceptable under a moral code if the cost to the animal (pain, unhappiness) is low.

However, I argue that it our our moral obligation to assume that the appearance of feelings means that the “cost” to animals of being farmed is high. To do otherwise is a rationalisation of our behaviour, rather than a logical justification for it. This reduces the ambiguity in the moral accounting for what is acceptable.

The conclusion is that vegetarianism should be the standard for everyone who aspires to a set of morals. Justifications remaining for eating meat are to disregard morality as something to aspire to, to find a life without meat miserable, or to make very strong and unscientific assumptions about the mental processes of (at least some) animals.


To determine the moral status of animals we must consider whether humans and other animals are fundamentally different, and what such a difference means, if it exists. This must be interpreted in the context of what we accept morality is, and therefore to whom it should apply.


People treat each other in general with a large amount of respect. We avoid killing each other without good reason, resolve conflict peacefully and work effectively together. All of this is done on the expectation that the respect will be returned, and so by mutual agreement society functions. Without this “code of conduct”, which coincides with many definitions of morality, we would still be living in close family groups engaging in permanent tribal warfare. This is a logical explanation in terms of selfish behaviour for morality between humans. Should this be extended to animals?

This is a complex problem. We have a different different relationship with animals than with other humans. Firstly, animals have no power over us, so are not capable of exploiting us in return. Secondly, they are not capable of making moral decisions themselves. Although altruistic (so perhaps “moral”) behaviour has been seen in dolphins (also Connor, 1982) and great apes amongst others, it certainly isn’t common to all animals. Thirdly, we cannot communicate with them, which means that we cannot come to an agreement for moral behaviour with them even if they could understand it.

So what is morality? Standards of morality change. For the purposes of this discussion, “moral behaviour” means acting in a way that is “fair”. This means that we extend the same rules to all, and agree to stick by them. It means that we should not harm others simply for the sake of it, and we should “do unto others as you would have them do unto you”. This does not mean that conflict does not arise, but that all have “implicitly agreed” the rules by which it takes place. For example, a morally sound war might break out over resources according to the Geneva convention. Or, if less food or water was available than was needed, we might fight and kill, but only to get as much as we needed. It may be morally acceptable to kill for personal need, or even personal gain, as long as we accept the same may happen to us. The particular rules that we agree to are implicitly or explicitly defined by society.

Our society has certain explicit rules – for example, do not harm another without good reason. What are the implicit rules we have agreed to? This depends on our take of what morality really is, and what it is for. There are three main stances we can take:

  • “Selfish morality”: we should behave in a way that appears moral, because it is good for us, in the long term. Cheating is therefore acceptable if we don’t get caught, and we should accept it (but not tolerate it) in others.
  • “Pragmatic morality”: we should actually try to adhere to the moral code because it is the “right” thing to do, provided that it isn’t “too costly” for us. There are two extremes defining this cost. “Equalisers” will accept harming others by an amount equivalent to what is gained. “Essentialists” will take only cause harm to others when it essential for their own well being. In reality people are in between, but these are the only two rational positions.
  • “High morality”: we should stick to the moral code no matter what.

These are not stances on how we actually behave, but on how we intellectually view the moral code. Selfish morality is almost certainly how moral concepts arose in humans, because it encourages co-operation (Axelrod 2006). It is not the same as amorality, since a selfish moralist may still feel guilt and therefore obey the moral code. To give an example of the practical differences, a selfish person could justify stealing bread from a starving man just because they wanted it. A pragmatic person could justify stealing that same bread only if they would die if they did not, but may justify stealing from the rich if they felt their need greater. A highly moral person would rather starve themselves.

Each person can make their own choice as to what morality really means to them. “Selfish morality” is observed in many powerful people, so perhaps many people secretly selfish. Many people do aspire to be “better” than selfish morality would dictate, and might be pragmatically moral. High morality, on the other hand, is not going to be favoured by evolution. If “moral people” wish to convert the world to their view, then those who stick to high morals will lose out physically to those who do not. Historically they would be conquered, and today they will be an ignored minority. Arguably, pragmatically moral people may be able to compete with the selfishly moral by punishing those that cheat (also Fowler 2005).


Our power over animals is often used to justify animal exploitation, because they do not have the mental ability to exploit us. Does that give us the right to do as we please with them? Perhaps we can compare the situation with slavery where one group enjoys complete control over another. But this is not entirely fair, because slavery actually is “bad” in the long term even for the masters. Slavery has been selfishly moral in the past but is not long term moral in any of the above senses because it harms the society that uses it. By condoning slavery, we implicitly accept that we might also become slaves. This destroys trust between different peoples and leads to a reduction in trade, and eventually to a loss of power.

There is no such requirement to extend moral protection to animals. The selfishly moral can use power to justify doing as they please to animals, provided that they don’t harm human society in the process. They might choose to prevent extinctions, and to treat animals kindly, but only so that along the line they can help their own interests.

However, the pragmatically or highly moral try to adhere to a “real” moral code, so power to do something is no justification at all for doing it. It may be acceptable to cause harm to another, but only if our benefits exceed their cost. Does this “cost-benefit” system extend to animals, who lack the ability to adhere to it?


“Morality as an agreement” is the way that complex societies operate. In return for behaving morally, we expect others to behave similarly. If someone refused to do so, it is considered wrong and they will be punished. How do animals fit in this, who may not be capable of making such a moral agreement?

The inability of animals to abide by moral rules might be compared to that of a severely mentally disabled person. Is moral protection withheld from them simply because they are not capable of returning it? Clearly the answer (in successful societies) is no. Our current moral code treats them with respect and dignity within the bounds of the capability of our society. So the inability to agree to a morality is not reason to remove the rights given by that morality.

Since animals are not currently protected by our moral code, the analogy between mental disability and animal lack of ability must fail. Why do the severely mentally disabled have moral protection at all? This can be simply understood in selfish terms. The rules extend to all people, because otherwise (in principle) our relatives or ourselves may not be protected. People with mentally handicapped relatives would not tolerate others abusing them, and so morality has been to extend to those people for the good of the rest of society. Similarly, the same privileges extend to pets and other owned animals. This undermines the concept that morality should only apply to those that agree to adhere to it. Even the selfish extend moral rights to those protected by powerful parties, and true moral rights extend to all that do not choose to abuse them.


There are numerous cases of animals performing simple communication with humans. But we are supposed to be the more intelligent species – if we cannot learn to communicate on their terms, what chance do they have? If “morality” in a real sense exists, then until we can demonstrate that a given animal lacks the mental power to agree to a moral code, then we should assume that they have it. If they can agree to a morality, then we should extend it to them. Why? Because if we do not, a more powerful species than ourselves has no moral obligation to respect us. These “hypothetical aliens” need not exist but serve to demonstrate that moral protection extends to all, regardless of their power to enforce it. If morality is not just a selfish code to keep us playing nicely together, then we must make this effort before refusing moral protection to animals. To fail to do so is no different from past civilisations allowing slavery and exploitation of people who speak a different language.


Most religions believe that there is one thing that puts humans above animals: the soul. Note that this isn’t always the case: for example, Buddhism is a major world religion that believes that all animals have the same type of soul that humans do, and encourages respectful behaviour to animals and vegetarianism.

This is not an argument for or against religion, but a discussion of how a religious morality may extend to animals. Although we cannot demonstrate the existence or lack of a soul in either humans or animals, this may not be important for our choice of how to treat either.

Most religions have a holy book that is a dominant source of wisdom and knowledge. However, very few people believe that these should be taken as literal fact. People who do will doubtless have a very different definition of morality to the one I’m using here. However, there are a very many good reasons to believe that holy books are not literal truth, which would constitute a separate post. In short: fallible people are involved in writing them in the first place and maintaining what is in them over the years. Additionally, they were written to address the problems of the time, and so the moral lessons for us today may require interpretation.

If we accept that a holy book contains some “fundamental truths” but may not contain a literal “code of laws”, then it becomes a “framework” for morality. The moral code can be constructed from the meaning and context of the original text. Unless killing animals is specifically required, then it is optional. This means people have a choice as to whether to do it, and therefore it becomes a personal choice based on the overarching moral framework of the text.

Most holy books place animals role as being there to provide for man. For example, the bible condones eating meat and is generally condescending to vegetarians, but at least offers a choice: “He who eats meat, eats to the Lord, for he gives thanks to God; and he who abstains, does so to the Lord and gives thanks to God” (Romans 14). Regardless of having a soul, or of their relationship to humans, it is clear that exerting our dominance over animals is still a moral problem, and not just a religious one to be determined by citing a text.

Even if the general feeling of a holy book is not supportive of moral behaviour to animals, interpreted for the audience of the time this makes sense. Holy texts are mostly written at a time when not exploiting animals led to a weaker society (in military terms). Societies that shunned animal exploitation would have been bested by those that didn’t and so advice for followers would surely have been to make use of them. This is addressed in detail later, but for the moment it is enough to have established that religious morality should still be determined in the context of modern society.


There are significant physical and mental differences between humans and animals that are readily observable. Humans mold the environment around ourselves, whereas animals must adapt more strongly to the environment they find themselves in. Humans have complex language and culture, they wear clothes and make tools. They have strong emotions, feel empathy, are capable of abstract thought and even moralising. Are these differences enough to justify a different moral code for each?

Many of these benefits simply give us power, which is morally irrelevant. Toolmaking, construction and planning all simply make us more powerful. Many other differences are not really unique to humans. Language of sort is observed in birds learned song, whales calls, apes gestures and sounds and bee dances, to name just a few. “Cultural heritage” is observed in dolphins teaching each other how to dance on water, in birds and apes (Whiten 2005a) teaching each other techniques for obtaining food, and even distinguishes behaviour in fish populations (Whiten 2005b). Clothes are similarly an extension of both tools and culture.

Do animals feel emotions? We can’t know, because we can’t ask them or get into their minds. Do other humans feel emotions? Well, they look like they do. Animals clearly look like they do, too. Elephants show strong emotions, pining over dead relatives, and displaying altruistic behaviour in herds. Dogs show huge devotion to their owners and become sad when separated from them. The fear an animal feels when threatened looks like real fear, and likewise animals look like they feel pleasure. Without learning their language, we can’t know for sure if they claim to have emotions, but that is our failing, not theirs (as is not knowing if they even have language).

Magpies can recognise their own reflection, as can many apes and some other mammals, and even the octopus. This shows an ability for abstract thought, and (maybe) self-awareness. Hiding food only when unobserved demonstrates the ability to see things from others point of view. Many animals can solve complex puzzles for food, demonstrating the ability to plan and think effectively. Animals appear to be smarter than we give them credit for.

Does the appearance of emotion justify treating the emotion as real? We know that we can create robots that would appear emotive, without “feeling” anything real. However, there is a good reason to treat animal displays of emotion as “real”: they are related to us by evolution, and we consider our emotion “real”. Emotion in animals performs the same fundamental biological role as in humans, and is realised by a related set of chemical and mental stimuli. This is very different from “artificial” emotions created solely for the purpose of appearing emotive. Indeed, human evolutionary history indicates that as little as two million years ago, we were no more special than the best of the animals today. Since animals are related to us by evolution, it should come as no surprise that they demonstrate the same types of behaviour that we do, and that it is driven by a similar emotional and mental system.

There is still a quantitative difference. Many apparently intelligent animal behaviours are in fact simple response to external stimulus. For example, Beavers build dams as a response to the sound of running water. However, humans can also act inappropriately in response to stimuli, for example, sexual arousal from an image rather than presence of the opposite sex. Would an anatomical human who was devoid of cultural influence fare well in tests performed on animals? I certainly feel that I would struggle if I was thrust into a series of unfamiliar situations, without any direction of what I was supposed to do. How much of “human intelligence” is thousands of years of cultural inheritance? Although clearly the ability to maintain such cultural inheritance is a major feature of humans, culture does exist in animals at a smaller scale. They apparently feel the same emotions we do, and perhaps as strongly. From a moral viewpoint, it is up to us to prove that they don’t.


The definition of “pragmatic” morality allows for conflict. It is a given that all individuals will behave selfishly at some level. Certainly their ancestors must have. If one person does not exploit a resource out of morality, then another might and kill the fool who didn’t. Therefore exploiting animals in mankind’s ascendancy was inevitable, and pragmatically moral.

Animals provided us with food, with clothes and with tools. They provided labour to build things, transportation, and effectiveness in warfare. We need none of those things from animals today. Animal products and labour are, for the most part, outdated. Animals are now primarily exploited for food and clothing.

It is not necessary any more to exploit animals. It does not give either the individual or society an advantage – we do it solely because we like to. We enjoy eating them, and we like the clothes that can be made from them. Is this a morally justifiable position? If we are trying to adhere to a real morality then animals qualify for moral protection, and it becomes a matter of whether the cost to them is justified by the benefit to us.


The definition of pragmatic morality allows the exploitation of others provided that it gives us an actual advantage. It is not enough to just “want” to do something, but instead something valuable must be gained. A advantage over a competitor is always “valuable” enough to the pragmatically moral, because otherwise moral individuals will lose to selfish ones. Are there things that have real value without giving an advantage?

The answer is yes.  For example, religious people may find value in living according to their faith, and the truly moral may find value in adhering to a moral code. But all will find value in happiness, and this is where degrees of pragmatic morality arise.

A pragmatic moralist will have no problem with harming others if their life depends on it. What if the benefit comes in the form of happiness or pleasure? What cost to another justifies the benefit to self, given that the system of morality assumes others may act similarly? Here the cost and benefits must take into account all factors (e.g. emotional distress) so doesn’t relate to monetary value.

Clearly, causing more harm to another than the benefit you gain is not justifiable morally, and falls into the selfish morality category. There are two morally consistent levels. “Equalisers” may justify causing as much harm as the benefit they gain. “Essentialists” only justify causing harm if the benefit is competitive. Between these some cost/benefit ratio is acceptable, but this is not a consistent stance. Since a tiny extra cost shouldn’t change our choice, standards can just keep lowering to the point of equalisers. In reality most pragmatic moralists will not belong to either category, since it takes a number of “tempting” opportunities to erode standards.   An example of something with high benefit and low cost is copying music or movies.  The exact cost and benefit depends on whether the individual would have bought the item if they didn’t pirate it, whether the copyright owner was large and successful or small and poor, etc.

With humans, (hopefully) our knowledge of society allows us to be good at calculating the cost and benefit, taking into account many complex factors, and this usually allows us to interact fairly. With animals, things are less clear. Because we don’t share language, we can’t ask them how much they value something we might take away. We are left to inexpertly interpret body language and behaviour. However, by the discussion above on language, if we are attempting to adhere to a set of morals we must err on the side of generosity. To do otherwise is to choose to interpret things in a way that benefits ourselves, and is therefore a selfish rationalisation.


So how do animals perceive value? They appear to appreciate comfort and living a life free of unusual stresses. This is a justification for giving them happy (and close to natural) lives. Doing so is a huge benefit to them and small cost to us (i.e. small and monetary, which current society can manage at little real cost), so this should be (and usually is) a requirement for all pragmatic moralists.

Can we nevertheless kill animals to eat, if we treat them well? Since many people enjoy eating meat they gain a benefit from this. What is the true cost to the animal? Assume (unrealistically) that the killing is performed so humanely that the animal does not know what is happening to it until it is dead. Everything has to die eventually, so why not eat it?

To establish bounds on the cost, consider how this life might affect humans. Despite never being aware of what way happening, this manner of death is still terrible to us. We place huge value in the “freedom” of being in control of our own destiny, in being able to live our lives to our own values, and in not being exploited. We also assign value to these things being actually true, rather than us simply being unaware that they are not. Do animals also assign value to these things? Again, a comparison can be made to the severily mentally handicapped. Do they assign value to these things? We cannot ever know since we cannot communicate enough to ask them. Probably, the value of these things increases with mental capacity, but without knowing otherwise we are morally obliged to assume that animals find some value in them.

No system for tricking animals into believing they are in a natural or pleasant life when they are really being farmed can be perfect. The experience of being raised for meat will bear a cost to the animal, since it must contain confusing and unnatural environments especially at slaughter. More importantly, the mysterious loss of other animals they have emotional bonds with (including parent/offspring bonds) can never be mitigated amongst animals that form them, which all herding animals appear to do. All of these contribute to a cost from the animals perceived life value, which we must assume it has until we can prove otherwise.

Given that humans no longer gain anything essential from eating meat, anyone proscribing to either “essentialist” or “higher” morality should not logically eat meat. Additionally, since the benefit to eating an animal is typically low, the benefit only outweighs the cost if we assume that animals are too dumb to experience much “cost” when being farmed. An “equalist” moral system therefore requires the assumption that animals feel very limited pain and emotion. To do so requires placing great faith in the stupidity of animals, because if there is any doubt there is a moral imperative to err in the animals favour. Given the apparent emotions seen on most higher animals, is this reasonable?


Of course, people are not logical and we all hold an incompatible set of beliefs. We may be highly moral on some issues but amoral on others, or use good deeds to somehow “offset” guilt. I expect that few readers will have thought things through to this level of detail, and therefore most will be wary of my logic.  Others may reject my assumptions or definitions. If you don’t agree, please do comment so that I can address the issue, or admit I’m wrong! Regardless, I hope that I have made you think, and perhaps to admit (if only to yourself) exactly where your morals lie.

These are all very personal definitions of moral stances which I expect to be flawed or incomplete, since I am not a philosopher.  All I can claim is they fit the possibilities that I have thought of.  I don’t think that the specifics are that important to the conclusion, however.

My personal moral stance is a pragmatic one, and I guess I have an irrational cost/benefit ratio erring on the side of essentialism. I accept that selfishness is the most logical position, but I personally find “value” in trying to do the right thing. I don’t believe any of the moral stances discussed are “wrong”, except maybe a hypocritical one. A glance around the world shows that though selfishness is common, many people are trying to “be someone good”, and not just for recognition. Most impressively, despite our different opinions we can agree to treat each other with respect. Thanks for taking the time to read this!


Note that the wikipedia links were factually correct on the topic of the text (compared to at least one of their primary sources) as of 23/08/08, and were used since they give a readable description.

Axelrod 2006, The Evolution of Cooperation. Basic Books.

Connor, 1982. Am. Nat. Vol. 119, No. 3 , pp. 358-374.

Fowler, 2005. PNAS. 102:7047-7049.

Whiten, 2005a. Nature 437, pp. 52-55.

Whiten, 2005b. Nature 438, pp. 1078.


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Why do atheletes cheat?

August 17, 2008 at 2:04 pm (science) (, , , )

This very interesting article by a scientist who was a former world class cyclist discusses why taking drugs is likely to be the norm for many high end athletes.  Why?  Because the system favours it.  This can, surprisingly, be demonstrated very easily with mathematics known as “Game Theory” (don’t worry, the article is free of maths).

Roughly speaking, taking beneficial drugs (“doping”) is worth it because it both increases your chances of winning, and decreases your chances of being cut from the team.  Playing by the rules is the “suckers” option, since your chances of getting cought are so low.

Of course, the analysis is somewhat simplistic.  In reality, whether someone should (rationally) cheat depends on their skill level, whether their teammates are cheating, whether their team supports the cheating, and more.  The suggestions for fixing the cheating problem do address these issues, however.  They include: punishing the whole team if one is found cheating, lifetime bans for the cheater, and allowing cheaters to speak out after the event without punishment.  This will increase the chances of being caught, and decrease the likelihood of teams having “organised” cheating.  It will also help to identify teams that persistently cheat so that they can be more extensively tested.

The theory is based on the “prisoners dilemma”.  In sports terms, the problem can be written in terms of a “payoff” (i.e. money) that the athlete may expect depending on whether they cheat, and whether their opponent does.  If both players don’t cheat, they both have even chance to win.  If they both cheat, then they both have an even chance to win but might get caught.  But if one cheats and the other doesn’t, the cheater will most likely win and most likely not get caught.

Prisoners dilemma for athletes: Payoff is the prize for winning multiplied by the probability of winning it, minus the penalty for being caughht cheating, multiplied by the chance of being caught.  Your action is on the left.
Your action Opponent action
Don’t Cheat Cheat
Don’t Cheat $2M $0.5
Cheat $3M $1

From this, it is clear that whatever the opponent does, it is best to cheat. The dilemma is that if neither player cheats, then they are both better off than if they both cheat! Of course, the simplest solution is to reduce the payoff for cheaters, so that whatever the opponent does, your payoff is higher for not cheating.

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To improve safety in the classroom…

August 17, 2008 at 12:10 pm (Humour) (, , , , )

Shouldn’t teachers wear condoms all the time?

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August 12, 2008 at 10:47 pm (Uncategorized)

I’ve been quiet recently – its the danger of computer games! Oops…

It really does feel like an addiction sometimes.  I don’t play games very often, but when I do… well, I’m gone until I’ve had my Fix.  This was System Shock 2 – a very old game now, but still great.  There is nothing as scary as creeping around the dark corridors of an abandoned station, hearing the moans and clunks of the monsters hunting you, knowing you’ve only got one bullet left and they can kill you in one swipe.

Well, perhaps there is.  I got some VERY scary looks from Anna for playing so long!  Heh…

But now I’m back, the itch is scratched and I can continue with life again.  Until Spore comes out of course!

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A bit like stealing…

August 3, 2008 at 11:23 pm (cartoon) (, , , , , , )

… but not very much.

Its either the downloading or the analogy that is wrong here...

Its either the downloading or the analogy that is wrong here...

Authors note: Not only does this discuss the very important contempory issue of chocolate versus any other ice cream, it also has pirates who are ninjas.

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