Should Veg Advocates Use Health Arguments?

There are occasionally debates about how we can best advocate for veganism. Usually these debates take place between ethical vegans, so (unsurprisingly) the conclusion is usually that ethical arguments are the best approach.

For example, the Animal Activist's Handbook calls health-based arguments "problematic" and urges readers to focus on ethics-based approaches. No less an authority than Mahatma Gandhi said in his book The Moral Basis of Vegetarianism:
I notice also that it is those persons who become vegetarian because they are suffering from some disease or other - that is, from the purely health point of view - it is those persons who largely fall back. I discovered that for remaining staunch to vegetarianism a man requires a moral basis.
Like a lot of marketing advice, these theories are usually justified by an appeal to intuition, and like most such appeals I suspect that they aren't well supported by the facts.

A review of US meat consumption found that health information (as measured by the number of articles published in medical journals about the bad effects of cholesterol) had a stronger effect on demand than even price changes. A similar review of Canadian meat consumption found that government recommendations to eat less meat appear to have a significant impact. Concerns about cholesterol have sent the demand for butter and eggs plummeting. As Oprah fans know, information about the unhealthfulness of beef causes a huge drop in beef consumption - without increasing the consumption of pigs or chickens.

In a survey by the Vegetarian Journal, 82% of readers stated that they became vegetarian for health reasons, and among adolescents a vegetarian diet seems to be linked with a desire for weight control. This is confirmed by the Vegetarian Times' survey, which found that the majority of self-described vegetarians do it for health reasons. In a psychological survey of the origins of vegetarianism, the authors found that slightly less than half of vegetarians originally quit eating meat for health reasons. Vegetarians of all stripes are significantly more likely to be concerned about health aspects of their food.

And we shouldn't think that someone who becomes veg*n for health reasons will be less committed. An attempt to understand the process of becoming vegetarian found that slightly more than half the subjects were vegetarian for ethical reasons, but "health vegetarians became increasingly aware of animal welfare issues and this reaffirmed the transition." Indeed, the initial ethical/health distinction seems to fade over time as ethical vegetarians become more interested in health, and vice versa.

Unspeakably more depends on what things are called, than on what they are. - Friedrich Nietzsche

It's critically important to consider here too the benefit gained from advocacy that is not "vegan advocacy." You probably have heard of pink slime, a filler used in ground beef. The public outcry sent beef prices plummeting, causing at least one producer to declare bankruptcy. Several lawsuits regarding E. Coli-infected beef caused Topp's Meat Company to file for Chapter 11 a few years ago. The Hallmark/Westland Meat Packing Company went bankrupt after an investigation by the Humane Society of the US caused the largest beef recall in history - not because of animal cruelty violations (which were horrendous), but because of health concerns.

Bruce Schneier has said that no one should be concerned by what's on the news - if it's newsworthy, it's by definition unusual, hence it almost certainly won't affect you. This is a fact which a lot of advocates seem to forget. Pink slime is probably no worse than any other type of meat, yet some combination of branding, luck and timing caused tremendous economic damage to the beef industry. Similarly, your chance of dying from E. Coli even during an "outbreak" compares favorably with that of being struck by lightning, yet we find massively expensive recalls happening on an almost weekly basis.

So we have to be extremely careful when evaluating things like the evidence that vegan diets help with long-term weight loss. They stack up pretty well when compared to the competition, but the fact that they aren't overwhelmingly better than anything else doesn't necessarily mean that the health argument fails veganism.

Maybe health benefits aren't the best way to present veganism. Certainly there is a subgroup of people that is more responsive to ethical arguments than health ones, and we have to be careful about change which moves people from one type of animal consumption to another (although the evidence seems to indicate that this is less of a problem than one might think). But I hope I've convinced you that this is not something which can be decided by navel-gazing - it needs to be decided empirically, by doing surveys, handing out pamphlets and measuring what works.

If you are interested in learning more about health-based arguments for veganism, PCRM is a good place to start.

Don't "Raise Awareness"

In an early analysis of efforts to convince people to act more pro-environmentally, Burgess et al. present the following flowchart on how people's minds change:

It seems pretty straightforward. It's also completely wrong.

In a later metasurvey, Kollmuss and Agyeman say:
These models from the early 1970s were soon proven to be wrong. Research showed that in most cases, increases in knowledge and awareness did not lead to pro-environmental behavior. Yet today, most environmental Non-governmental Organisations (NGOs) still base their communication campaigns and strategies on the simplistic assumption that more knowledge will lead to more enlightened behavior. 
Problems go even further. Kollmuss and Agyeman add that "quantitative research has shown that there is a discrepancy between attitude and behavior." Wong and Sheth agree, saying that the relationship between beliefs and behavior is generally found to be "low and nonsignificant."

25% of Americans tell pollsters that "Animals deserve the same rights as people," yet only 2% are vegan. Unless a quarter of Americans believe it's ok to torture humans to death for their flesh, that's a pretty big gap between beliefs and behavior.

Henry Spira, one of the most effective animal advocates of all time, noted this problem in his list of tips for advocates when he disparaged "raising awareness". It's very easy to convince ourselves that we're building "mindshare" even if people's behaviors don't change, but without the explicit measurement of the sort that EAA's Top Charities do we're probably just building castles in the air.

Kill the Young People

Suppose you were forced to choose between killing someone today, and killing someone a century from now. Which would you choose?

To be clear: the two people are exactly the same - equally happy, healthy, etc. And the effects on others are the same, and there is no uncertainty involved. The only difference between the two murders is when they occur.

It seems hard to give a justification for why one is better than the other, and in the landmark Stern Review on Climate Change the eponymous Nicholas Stern said as much. In his interrogation by Parliament, he stated that to choose one over the other is to "discriminate between people by date of birth," a position that is "extremely hard to defend".

There is a lot of controversy about whether he made the right decision, mostly motivated by the fact that even slightly different decisions on how we "discount" the future can cause huge differences in how we respond to threats which will kill people in the future, like climate change.

A remarkable proof by Peter Diamond shows that, under some reasonable assumptions, we should indeed "discriminate by date of birth," and choose to kill the person a century from now.

Diamond's Proof

The full proof (and several others) can be found in his paper The Evaluation of Infinite Utility Streams, but I'll present a simplified version here.

First, some notation. We denote welfare over time as a list, e.g. $(1,2,3)$ indicates that at time 1 all sentient persons have utility 1, and time 2 they have utility 2 and so forth. Because time is infinite, these lists are infinitely long. We denote infinite repetition with "rep", e.g. $1_{rep}$ is the list $(1,1,1,\dots)$. These lists are given variable names - I use $u,v$ for finite lists and $X,Y$ for infinite lists - and they are compared with the standard inequality symbols ($>,\geq$).

There are four assumptions:

  1. If $u\geq v$ then $u_{rep} \geq v_{rep}$. I.e. if some finite list of utilities $u$ is better than some other finite list $v$, then repeating $u$ for all of eternity is better than repeating $v$ for all of eternity.
  2. If $u\geq v$ then $(u,X)\geq (v,X)$. I.e. if $u$ is better than $v$, starting off the world with $u$ is better than starting things off with $v$, given that the rest of time is equal.
  3. If $X\geq Y$ then $(u,X)\geq (u,Y)$. I.e. if some infinite state of affairs $X$ is better than $Y$, starting them both off with $u$ won't change that.
  4. If $u$ is the same as $v$ except some people are better off (and no one is worse off), then $u > v$. (This is sometimes known as Pareto efficiency.)
Proof: The proof actually isn't that complicated, but it looks intimidating because the notation is probably unfamiliar.

Suppose, for the sake of contradiction, that $(1,2)_{rep}\geq (2,1)_{rep}$. By (A4), $(2,2,(1,2)_{rep}) > (2,1)_{rep}$ since $(2,2,(1,2)_{rep})$ is the same as $(1,2)_{rep}$, except with people being better off at $t = 1$. By rearrangement, $(2,2,(1,2)_{rep})=(2,(2,1)_{rep})$ and $(2,1)_{rep}=(2,(1,2)_{rep})$ so $(2,(2,1)_{rep}) > (2,(1,2)_{rep})$. But we had assumed that $(1,2)_{rep}\geq (2,1)_{rep}$ which by (A3) means that $(2,(1,2)_{rep}) \geq (2,(2,1)_{rep})$. We've reached a contradiction, meaning that $(1,2)_{rep} < (2,1)_{rep}$.

This means that $(1,2) < (2,1)$, for if the opposite were true, $(1,2)_{rep} \geq (2,1)_{rep}$ by (A1). Therefore, by (A2), $(1,2,X) < (2,1,X)$, meaning that if we could shift happiness from year two to year one, we should.

We should value the happiness of those born earlier more than those born later, and kill the person living a century from now.


My girlfriend pointed out to me that the reason why we interpret this theorem to mean that people born earlier matter more is because we assume time has a beginning but no end. If we assumed the opposite, then people born later would matter more.

Should you walk or run when it's hot out?

Thanks to global warming, I've gotten the pleasure of walking to work in excruciatingly hot conditions recently. As I was walking to my office yesterday, I started thinking "it's so hot - I should hurry inside to get to the air conditioning." But of course, if I hurried then I would burn more energy and heat myself up even further!

Despite the wide body of literature available on whether one should walk or run in the rain, I couldn't find any suggestions on whether to walk or run in the heat. So I decided to do some investigating.

For a 150 pound person, walking at three miles per hour (a moderate pace) burns 230 Calories per hour. Walking at four miles per hour (a brisk walk) burns 350 Calories, and five miles per hour (a near run / slow jog) burns 544.

In 30°C temperature (~85°F), the sun gives off 400 Watts per square meter of heat from solar radiation, about half of which is immediately reflected (depending on your skin color and clothing). While most peoples' body surface area is around 1.8m2, only about half of your body will be directly receiving the sunlight, so we'll assume that you're getting ~200 Watts of power from the sun, which equates to 172 Calories per hour.

Lastly, we need to consider convection (or "wind chill"). The "wind chill factor" can be approximated as $8.3\sqrt{w}$, with $w$ the wind speed in meters per second. Skin temperature stays fairly constant around 34°C, meaning that in our 30°C weather there will be a temperature differential of 4 degrees. Change in heat is the product of the temperature difference, wind chill factor and body surface area. For a standard person, this gives us $$\frac{dQ}{dt}=8.3\times \sqrt{w}\times 4 \times 1.8 = 59.8\sqrt{w}$$ which we can integrate to find our total heat loss.

If you walk at three miles an hour, you will gain 230 C/hr from the exercise, and spend 1/6 of an hour outside to walk 1/2 of a mile. While outside, you will gain 172 C/hr from the sun, but lose 60 C/hr from convection, for a total gain of 112 C/hr. If we multiply this all out, we find that you will gain a total of 57 Calories of heat from your exercise.

Repeating the calculations gives us that you increase by 56 Calories when walking at four miles per hour, and 64 Calories when walking at five.

So my recommendation is what you would probably expect: a brisk walk will cool you off a little, but don't jog or you'll just end up soaked in sweat.

(All numbers and formulae taken from Physics of the Human Body. See this gist for a small octave/matlab script if you want to play around with the numbers. It would be interesting to consider the effects of humidity and higher temperatures, if you're up for it.)

Animal Welfare is Animal Abolition

Gary Francione is known for promoting what he calls the "abolitionist approach" to animal rights. Essentially, this means he is against improving the welfare of farm animals via legislation, viewing this as ineffective or even counter-productive. Instead, he argues that we should be unequivocal that veganism is the "moral baseline" of mankind.

The name comes from slavery: "abolitionists" were those who argued that any form of slavery was immoral, and must be eradicated immediately. This is opposed to general "anti-slavery activists" who wanted a gradual phase out of some, or perhaps all, slavery.

An under-appreciated point is that very few anti-slavery activists were actually abolitionists, and the term was more often used to slander the Republican party. Just as Obama increased government funding for health care and was labeled a "socialist," Abraham Lincoln ran on a platform of slightly improving the well-being of slaves and was labeled an "abolitionist." (He supported, for example, the Corwin Amendment which would have amended the Constitution to ensure slavery in states where it already existed - hardly an abolitionist stance.)

Even when Lincoln had the war-time power to issue "Executive Orders" (i.e. laws which didn't have to pass Congress), his famous Emancipation Proclamation did not, despite your 8th grade history textbook, made slavery illegal. It only freed about 75% of current slaves, and said nothing about the practice of slavery itself. (Slavery was later made illegal by the 13th amendment.)

The moral of this history lesson is that change is slow, and often requires making deals with the devil.

But I digress. The point I wanted to make is that there really is no way to work towards improving animal welfare without working towards abolition. This comes from what economists call the Law of Demand:

Consumers buy more of a good when its price decreases and less when its price increases.

This law is self-evident enough that I don't think it requires any argumentation. To make clear its relevance, we can rewrite it:

Consumers buy less meat when its price increases, due to increased regulations in the form of larger cages, more frequent veterinary inspections, etc.

We can in fact directly calculate the "abolition coefficient" of a welfare change. The elasticity of demand is a measure of how demand for a good changes relative to its price. Because we live in a country bloated with agricultural subsidies, armies of economists are employed to predict how demand for various animal products changes with price. Here's a table taken from Huang:


Elasticity is a measurement of percent change. So for beef, a 10% increase in price leads to 6.1% fewer cows on factory farms.

The precise calculation of how much a given law will change the lives of animals is of course complex. But the important thing to note is that these elasticities are always negative - more expensive meat always leads to less meat. Always.

(An important consideration is to wonder if increasing the price of chicken will just drive people to eating beef instead, a rather dubious gain. You can see from e.g. Eales and Unnevehr that, while this does happen to some degree, people do substitute vegetables for meat, meaning that there is a real gain.)

Why there must be universal grammar

The guardian ran an interview with Daniel Everett yesterday. Everett is a linguist most famous for his claim that universal grammar (the belief that some rules of grammar are "hard wired" into the brain) as popularized by Chomsky, is false. Specifically, he believes that the Pirahã language lacks recursion.

His claims are quite controversial, but one thing which is worth mentioning is that universal grammar is (for a reasonable definition of "proof") provably correct. By this I mean:

Theorem: Learning grammar is so hard that the only way humans (or anyone) can do it is if they have innate structures.

This is related to Chomsky's poverty of the stimulus argument.

It can be proven in the following way: suppose we restrict ourselves to just the subset of English sentences consisting only of nouns and verbs. "I like John" and "You are here" would be two examples. These both follow the pattern "noun verb noun". A sentence like "jump run you" is non-grammatical, because "verb verb noun" is not an acceptable pattern in English.

Now let's consider how long it would take a learner to learn these patterns. There are 23 = 8 possible patterns of length three, so if a learner thinks they're all possible, it will have to test out all eight of them. ("Mommy, is 'jump run you' a sentence?")

Most sentences have much more than three words of course, so a learner will need to test out the 24 = 16 four word patterns, the 25 = 32 five word patterns, etc. In general, there are 2n possible sentences with n words, meaning that the number of tests that the learner will need to run is exponential in the number of words.

The Cobham-Edmonds thesis states that any problem which takes exponential time is, in practice, unsolvable.

Why is this true? There are, depending on your definition of "part of speech", about 20 parts of speech in English. If you tested one grammar per second, it would take you about a month to learn all the five word grammars. The six word grammars would take you two years, and you would be forty before you learned all the seven word grammars. That last sentence had 22 words, and it would take you 1021 years to test all of the 22-word-grammars. The universe is only 1013 years old.

So who knows whether all languages are recursive. But it seems unlikely that human children consider all possible grammars equally. They must use some shortcuts and those shortcuts must, by definition, be innate.

Thoughts on Sokal v. Lynch

The New York Times ran a debate between Sokal (of Sokal affair fame) and Lynch regarding the underpinnings of science, apparently sparked by Rick Perry's denial of evolution. I've read several "why science is better than religion" things like this, and none of them ever give what I see as the obvious proof, so I'd like to contribute it here.

If you have some theory which works 10% of the time, and you do one experiment, there's a 10% chance you'll falsely believe your theory is good. Do two experiments, and that probability drops to 1%. Three, four, ..., N experiments later, and the likelihood that you'll have seen all false positives is vanishingly small.

Another way of putting this is: the law of large numbers says that, if you do a large number of experiments, you'll tend towards the right answer. If evolution is supported by vast amounts of evidence, the probability of it being wrong is so small as to be inconsequential. This has nothing to do with experimental science, it's just a mathematical fact. QED.

I guess Prof. Lynch will tell me that the mathematical assumptions which underlie the law of large numbers are just as suspect as the assumption that the bible is infallible. Maybe, but it strikes me that few fundamentalists are claiming that 2 + 2 = 5, indicating that much progress could be made by making clear the mathematical foundations of science.

I'll leave you with what I think is Sokal's best argument (tragically not in that op-ed):

Anyone who believes that the laws of physics are mere social conventions is invited to try transgressing those conventions from the windows of my apartment. (I live on the twenty-first floor.)

A Simple Proof: Occam's Razor

How do you know that I'm not a robot? How do you know we're not living in the matrix?

The usual resolution is some form of Occam's razor: sure, it's possible that I'm a robot, but the simpler explanation is that I'm human, and simpler explanations are preferable.1

This just pushes the question back: why are simpler explanations better?

There is a straightforward proof that comes from Computer Science, of all places, which I hope to explain here.

Suppose I enter the world as a blank slate - I have a "bag" of hypotheses about how things work, and I consider them all equally probable. As I perform experiments, I disprove some of my hypotheses, while others remain. As time goes on, my bag of plausible hypotheses gets smaller and smaller.

If I eventually reach a point at which I only have two hypotheses remaining and I randomly choose one to believe, I'm 50% certain that I've got the right one. But if I randomly believe one out of a hundred possible hypotheses, I've almost certainly chosen wrong (i.e. I've probably selected a hypothesis that by luck happened to fit with all the observed data, even though it's in fact wrong).

Believe it or not, this concludes the proof.

If I have a simple hypothesis ("fire is hot") there's really only one other hypothesis that could be in my bag ("fire is not hot"), so I can rapidly determine which is the right one. If my hypothesis is complicated ("fire is hot, provided it's the first full moon of a year with zodiac symbol ...") there are tons of equally complex hypotheses, and some of them are bound to fit the data, so I'm unlikely to have chosen the right one.

In my job, I spend some time in the back rooms at medical offices, which means I hear nurses complain about doctors, and doctors complain about patients. One conversation I had with a dietition sticks into my memory: she was complaining about patients who expect the faddish, complicated dietary advice you hear on TV - "good" carbs, antioxidants etc. - but all she does is give people a calorie target, and recommend eating more fresh fruits and vegetables.

I told her to give her patients a brochure on Occam's razor. I doubt they've implemented my suggestion.

Postscript: This proof is a vague mishmash of the motivation for Bonferroni correction and VC theory. Any book on computational learning theory will have a better one, but you can see de Wolf's thesis for an explicit application of PAC learning to Occam's razor. You might also like my post why you will never see an eight-sided snowflake.

  1. That's not true. The usual resolution is to ignore the problem.