Let us be the first to concede that the statement that lions eat meat is completely true. We have observed this phenomenon first-hand on the plains of Africa and can verify that it is in fact, a fact. It is also totally irrelevant to the argument at hand. Marshaling the claim that lions and other non-human animals eat meat as a defense of meat-eating among human beings is a classic example of the Naturalistic Fallacy, which is the erroneous assumption that anything that occurs in nature is therefore morally justifiable. This is of course ludicrous. Rape, murder, infanticide, necrophilia, and myriad other atrocities from which all well-adjusted people quite naturally recoil occur all the time in the wild, but no one is going to argue that their mere occurrence constitutes a moral or ethical justification for them. Nor do civilized people take their cues from the natural world by greeting one another –as lions are known to do– with a robust olfactory assessment of one another's hind-quarters. In polite society, such lion-like behavior simply will not do.

In biological terms, a lion is a predator and committed carnivore who has no choice but to hunt prey animals and eat them. If he does not, he will quickly perish. This is simply not the case with Homo sapiens, who are, anatomically speaking, frugivores. If you are reading this, you are not a lion and what applies to the lion with regard to sustenance does not apply to you. And what applies to you in terms of morality does not apply to the lion. Human beings are moral agents, whereas lions (so far as we can tell) are not and that, more than anything else, is the difference that makes the difference.

Your argument is invalid.

An imperishable favorite marshaled by otherwise rational people who wish to defend the carnist world-view goes like this: "Plants have feelings, too! How can you kill all of those innocent cabbages and still claim that killing animals is wrong? Haven't you heard about that study where the guy proved that plants have feelings?”

My response, until recently, had always been something to the effect of, “Why, yes, I have heard about that study, but somehow no particular scientist, university, or institution is ever mentioned in association with it. Were the results of this study peer-reviewed or published in a scientific journal?” No one who has ever been on the vegan side of this conversation needs to be told how those on the other side of it inevitably respond. There are never any names given, sources cited, or particulars offered, giving their claim all the mystique (as well as credibility) of an urban legend.

But just for the sake of argument, let's overlook the complete absence of scientific merit that the claim possesses and assume that it is somehow true that plants are conscious. Let us ignore the fact that plants do not possess brains or nervous systems and assume on the basis of no credible evidence whatsoever, that plants are sentient beings and that “psycho-botany” is a legitimate science.

Taking this claim at face value actually weakens the carnist's case against the vegan. There is a very obvious and important objection to the argument that, from an ethical point of view, eating plants is no better or worse than eating animals. This objection concerns the sheer quantity of plants needed to produce meat. Producing a single pound of beef, for instance, requires sixteen pounds of grain. One pound of pork requires six pounds of grain and for every sixteen ounces of edible chicken flesh that is produced, at least five pounds of innocent plants must lose their lives. In the United States alone, fifty-six million acres of arable land are dedicated to growing hay for livestock production, whereas only four million acres are used to grow fruits and vegetables for people. Thirty percent of the Earth’s land surface, which is equivalent to seventy percent of all agricultural land on the planet, is devoted to growing crops for and raising farm animals. And according to the American Journal of Clinical Nutrition, the amount of grain fed to livestock in the U.S. alone could feed about 840 million people, roughly eleven times the number of people who die of starvation every year.

We'll leave aside for the moment that these figures represent an egregious, immoral, and unsustainable misappropriation of the world's dwindling natural resources and we'll concentrate instead on the issue of suffering, which is of such great concern to the many meat-eaters who are convinced that vegans bear the responsibility for inflicting pain and misery upon innocent fruits, vegetables, nuts, seeds, and tubers.

If one is legitimately concerned with mitigating the amount of suffering in the world, then there is simply no way to justify eating meat, especially if one believes that plants also suffer. The misery and suffering of the tens of billions of animals raised and slaughtered for food every year are multiplied by hundreds of orders of magnitude if one accepts the claim that plants, as well as animals, possess consciousness and therefore suffer when they are harvested.

That killing and eating animals causes them to suffer is undeniable. That eating plants causes them to suffer is a proposition that has never been demonstrated in a controlled scientific experiment, despite the numerous efforts of scientists to determine the legitimacy of so-called “primary perception”. It's time we recognize the “Plants have feelings, too!” argument for what it is: a feckless attempt to undermine the ethical basis of veganism with pseudo-science and bad logic.

Your argument is invalid.

The anthropocentric claim that non-human animals were put on Earth for the benefit of H. sapiens constitutes an empirical claim about the world that contradicts an enormous number of respected and well-supported theories within the realm of science. All of the available data support the universal scientific consensus that all forms of life on this planet owe their existence to the slow, gradual process of evolution by natural selection and random mutation. That human beings have the ability to exploit non-human animals does not in the least imply that the world's non-human animals exist for the purpose of being exploited. Pigs and chickens do not exist for the benefit of human beings anymore than human beings exist for the benefit of the Yersinia pestis, the bacteria responsible for the bubonic plague.

There is nothing in the fossil record or in the modern scientific canon to suggest that either human or non-human animals were placed on this planet by anyone or anything. All of the available data and the prevailing scientific theories based upon them indicate very clearly that, just like us, everyone and everything else in the plant and animal kingdoms have evolved over the course of vast stretches of time. This inarguable fact reveals the assertion that animals were “put here” as a patent and absurd falsehood. And if animals were not put here, then it is impossible to adduce that they were put here for a specific purpose: least of all to be bred, enslaved, slaughtered, and eaten by human beings, whose anatomies are simply not suited to digest them.

The fossil record also leaves no question that in almost* all cases, the animals were here well before us. As a species, H. sapiens has been around for only about 300,000 years, whereas fossil evidence clearly suggests that all manner of birds, hooved mammals, and other vertebrate and invertebrate species whom humans routinely raise and slaughter for food have been around for much, much longer. So, anyone who claims that humans somehow have seniority on planet Earth simply doesn't know his science. And in any case, arriving someplace earlier than others doesn't give one carte blanche to do as one pleases with those who arrive later. 

Your argument is invalid.

*We qualify this statement with the word "almost" because some species of animals, such as the modern cow,  Bos taurus, are the result of thousands of years of selective breeding on the part of human beings. The modern cow is, in a manner of speaking, a human invention, although the evolutionary precursor to the cow, the aurochs, was around long before the first Homo sapiens arrived on the evolutionary scene. So, your argument is still invalid.

See also But They're Just Dumb Animals! and The Bible Says We Should Eat Meat!

Those who invoke the “Happy Meat Fallacy” when defending their choice to eat animals are making an argument that seems, at least on its face, somewhat less preposterous than most other defenses of the practice. “After all,” they reason, “Isn't it preferable for farm animals to live their lives in the bucolic serenity of verdant fields of clover, galloping insouciantly hither and yon, rather than living in the deplorable squalor and filth of factory farms? Isn't that more humane? More compassionate? More responsible?”

On the surface, this is a seductive argument and the seductiveness of it is not lost on the PR firms responsible for foisting the Happy Meat campaign upon the perhaps well-intentioned consumers who want to make “more responsible food choices”. But as with so many advertising ploys and marketing claims, the words and images used to sell Happy Meat are seldom congruent with the reality of “free-range” and “compassionate” farming. In the United States, the agency responsible for establishing food labeling terms is the U.S.D.A., which lists on its Web site the following sole criterion for the term “free-range”: “Producers must demonstrate to the Agency that the poultry has been allowed access to the outside.” That is literally the extent of their criteria. There is no requirement regarding the duration of access to the outside, nor anything that specifies what, if any, other minimal standards of care for the animals must be met.

It is, therefore, entirely consistent with the U.S.D.A.'s definition of “free-range” for a farmer to have a small door in an enormous shed that houses tens of thousands of chickens, and then to open that door for five minutes a day, thus giving the chickens “access” to the outdoors. And perhaps it should go without saying at this point that the outdoors to which these "free-range" chickens are given access needn't be a “range” in any recognizable sense of the word. A farmer could give his chickens five minutes of daily access to a gravel pit and still receive the U.S.D.A.'s coveted (and lucrative) certification for “free-range”. And as applied to eggs produced in the United States, the term “free-range” has no legal definition whatsoever; nor is there even a common set of “free-range” standards established by the industry itself, making the term utterly meaningless when applied to eggs.

Unlike the term “free-range”, which could, at least in theory, have some substantial and relevant meaning, the term “humanely slaughtered” is a fatuous and obscene oxymoron. While some methods of killing an animal are admittedly less cruel than others, they all involve an unpardonable act of violence against an innocent and defenseless animal who had, in most cases, lived only a fraction of her natural life: a life which she valued and which she forfeited in abject terror, regardless of the method used to take it.

If you have compassion for animals and if you believe that they have the right to be treated decently and to live free from unnecessary suffering, then there is no system of breeding, enslaving, and slaughtering them that will suffice and you should not allow your conscience to be mollified by dubious marketing claims. All such systems of exploitation are, by their very nature, antithetical to the interests and the rights of animals. Regardless of the marketing claims that surround them, they are based on the morally indefensible premise that non-human animals are, or can be used as, commodities, objects, and machines. And in any conflict concerning the rights of a machine and the interests of the machine-owner, it is the machine that invariably loses. And doesn't this inherent asymmetry make all claims of “compassionate” and “humane” exploitation and oppression of non-human animals disingenuous, at the very least?

And when, as articulated above, the terms are as misleading and as vacuous as “free-range”, there is scarcely any reason to believe that the premium paid by the consumer at the supermarket for the tacit assurance of some measure of decent treatment toward the animal actually corresponds to any appreciable difference at all in that animal's life, or for that matter, in her death.

Your argument is invalid.

Sources:

http://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/food-labeling/meat-and-poultry-labeling-terms/meat-and-poultry-labeling-terms

https://en.wikipedia.org/wiki/Free_range

http://www.upc-online.org/freerange.html

The implication of this argument is that eating is an entirely private matter in which no outside authority should have the right to interfere. Those who employ this argument often do so with the same air of indignation as those Second Amendment firearms enthusiasts who refuse to be quiet about their sacrosanct right to bear arms and who have recently gotten into the terrifying habit of brandishing semi-automatic weapons in grocery stores and restaurants. The meretricious allure of this approach is that it plays upon people's sense that their unalienable rights are somehow being infringed upon by a menacing third party who wants to impose its own agenda and values on everyone else and who has declared its right and intention to do so.

Of course, in order for a choice to be entirely personal, all those involved with or affected by it must give their consent. Punching a stranger in the face is a personal choice in the sense that it involves a decision on the part of one person to assault another, but that does not make it a “personal choice”. As the saying goes, “Your right to swing your fist ends where my nose begins.” Similarly, the “personal choice” to eat animals conveniently leaves out of the moral equation the very animals who are being exploited and slaughtered. The working assumption is that their rights and interests simply don't matter, or at least they don't matter as much as the gastronomic preferences of those who chose to eat meat, eggs, and dairy.

Another element of the equation that is universally omitted by the “personal choice” adherents is everyone else on the planet. The global animal by-product industry is responsible for environmental destruction and degradation on an enormous scale and everyone, including those of us who don't eat animals, has to live with the consequences. For instance, animal agriculture is responsible for more water pollution than any other industry in the world and the effects of that pollution are distributed equally among everyone, whether he or she contributed to the problem or not.

Here's a simple syllogism to help clarify the point:

Destroying the biosphere is not a personal choice.

The production of meat, eggs, and dairy is destroying the biosphere.

Ergo: eating meat, eggs, and dairy is not a personal choice.

Your argument is invalid.

In a very strong field of incredibly weak arguments against veganism, the Argument From Divine Authority is by far the weakest. The Bible does indeed say in Genesis chapter nine, verse three that, “Every moving thing that liveth shall be meat for you; even as the green herb have I given you all things." That is a pretty unequivocal statement from the Almighty; and just as unequivocal are the biblical injunctions for (just to take a few examples from a veritable cornucopia of atrocities) selling one's daughters into slavery (Exodus 21:7-11), murder, rape, and pillaging (Deuteronomy 20:10-14), and putting to death those who have the temerity to work on the sabbath (Exodus 31:12-15).

If you're going to use holy writ to justify killing and eating animals, then you place yourself in the highly unenviable position of having to accept such justification from others who use the same text to excuse and rationalize slavery, murder, rape, genocide, animal and human sacrifice, and a host of other divinely sanctioned obscenities and absurdities.

Anyone who accepts the Argument From Divine Authority with regard to eating animals has no choice but to permit it for rape, murder, slavery and the various other acts of barbarism and savagery that the Almighty enjoins the devout to commit. The only way out of this conundrum is to assert that some biblical injunctions should be taken seriously and others may simply be ignored. But this of course invites the inevitable and unanswerable question of who decides these things and on what authority?

Unless you believe that slavery, genocide, rape, and murder are okay, then the Bible is no guide to morality.

Your argument is invalid.

The short answer to this ridiculous question is “no”. Nothing within the popular conception of animal rights, animal liberation, or veganism even suggests that non-human animals should have the rights to vote in elections, get married, run for political office, obtain driver's licenses, or form Super PACs. We believe that all animals, human and non-human alike, have the right to be free from unnecessary suffering and harm. We believe that animals are not our slaves and that we are not their masters and that they have the right to be treated with respect, compassion, and dignity. These are all moral rights, which are distinguished from legal rights, such as the rights to marry and vote. Asserting or implying that the establishment of certain moral rights for non-human animals is either analogous to or will invariably result in the establishment of other unrelated legal rights is either to misunderstand or misrepresent the issue of animal rghts.

Those who are sincerely convinced that the recognition of the moral rights of non-human animals will somehow lead inexorably to the establishment of their legal rights are committing the Slippery Slope fallacy, which occurs when, according to the Skepdic's Dictionary, "[O]ne asserts, without providing any evidence to support the assertion, that an event or chain of events will follow the taking of some action you object to." Of course, there's absolutely no reason to believe that once we human beings arrogate to non-human animals the right to be free from unnecessary harm, it's only a matter of time before cows and chickens are crowding the steps of City Hall to be joined in wedlock.

The Slippery Slope fallacy is a favorite among the opponents of marriage equality, who assert stridently that once same-sex couples are allowed to marry, it's only a matter of time before people are marrying their furniture. As of this writing, marriage equality laws exist in eighteen countries around the world and the number of marriages between a person and a dining table remains zero. 

In the case of deliberately misrepresenting the issue in this way –rather than merely not understanding it properly– it constitutes a classic Straw Man Argument, in which one doesn't confront one's opponent's argument directly, but instead attacks a position that one's opponent does not actually hold and then rips it apart, like a straw man. As the writer Thomas Pynchon once so memorably said, “If they can get you asking the wrong questions, they don't have to worry about the answers.”

Sorry, Scarecrow, but your argument is invalid.

Whether Homo sapiens as a species have always eaten meat is uncertain. It is undeniably the case that meat and other products derived from non-human animals have a long history as a part of the human diet, but this fact says nothing at all about the moral or ethical propriety of breeding, enslaving, killing, and eating animals. Humans also have a long history of killing, raping, and butchering one another and until somewhat recently, it was perfectly legal in the United States to buy and sell human beings. Those slave-owners in the antebellum South who argued against the Abolitionists were fond of using the Argument From Antiquity to justify slavery, but it was not valid then and quite unlike a fine wine, it has not improved with age.

The brilliant poet and naturalist George Crabbe (1754-1832) articulated this fallacy beautifully in the following verse: “Habit with him was all the test of truth, / It must be right: I've done it from my youth.”

And it mustn't be forgotten that throughout the greater part of modern history, animal by-products constituted only a tiny part of the human diet. It wasn't until the advent of modern factory farming techniques in the mid- to late-twentieth century that meat, eggs, and dairy became such ubiquitous items on the plates of anyone not in the Ruling Class. This is thanks in very large part to the ability of factory farms to externalize the costs of their operations, an issue we'll address elsewhere. And it must also be remembered that abstinence from meat has a long and storied history within our species as well. From Pythagoras, to DaVinci, to Einstein, to Edison, and to Ellen Degeneres, there have always been those who recognize the indecency of killing and eating animals and who follow the dictates of their own consciences and not the example of the majority, be it past or present.

Your argument is invalid.

This is an argument often loftily put forth by those who take comfort in the childish notion that by eating animals they are somehow playing an important role in a glorious and unending cycle of life, death, and rebirth. These people fancy themselves as players in a Great Cosmic Drama, in which the dead are consumed by the living who will eventually die themselves and be consumed in their turn. It's Nature, don't you see?

The biggest problem with this line of reasoning (or should we say, “rationalizing”) is that it is based on a naïve and absurd fantasy. The Circle of Life argument simply doesn't take into account the brutal and completely unnatural way in which meat, eggs, and dairy are produced on the overwhelming majority of modern farms.

The life of a pig on a modern factory farm provides a representative example. Pigs on modern factory farms are separated into two categories, “breeder sows” and “meat breeds”. You know, just like in Nature. The natural life-span of a pig is between ten and twelve years, but on modern farms, breeder sows seldom live beyond five years, at which point they are sent to slaughter, and pigs raised specifically for slaughter will generally be killed at the age of six months, about one-twentieth of their natural life-span. The modern breeder sow is often kept in a gestation crate, a metal enclosure so small that she cannot stand up or turn around. She is fed enormous quantities of antibiotics, is kept indoors her entire life, and will be impregnated (either artificially or by a boar) as many as six times in the course of her unnaturally brief and miserable life. When the sow gives birth, her male babies will be castrated without anesthetic and the males and females alike will have their tails docked, their ears notched, and their tusks clipped, also without any anesthetic.

The runts of the litter, those piglets who have the misfortune of being born smaller than their siblings and who therefore show little promise of growing to market size, will be destroyed by any of a number of different methods, a common one being simply to pick the pig up by her hind legs and smash her violently against the concrete floor until she is dead or unconscious. This is often done in full view of both the mother pig and her other offspring.

Those piglets who have been deemed suitable for eventual slaughter will then suckle from their mother until they are large enough to be placed inside a metal stall with a concrete floor and in which they too are unable to turn around. They will be fed a diet unlike anything an omnivorous pig in the wild would ever eat, consisting mostly of cereal grains supplemented with antibiotics and synthetic vitamins. And whereas it takes about five years for a wild hog to reach 250 pounds, modern “meat” pigs will swell to that unnatural weight in just six months, at which point they will be sent to slaughter.

If the pigs survive the agonizing trip from the CAFO to the slaughterhouse, they will be taken from the transport truck and shot in the head with a captive-bolt stun gun, which may or may not render them unconscious. They will then be hoisted into the air on a chain by one leg and their throats will be slit in full view of other pigs. At this point they will be conveyed, sometimes still fully conscious, along the disassembly line which begins with a vat of boiling water, into which they are dunked, the intention being to soften their hides for the butchering that is to follow. The pigs are very often still alive at this point in the process and they react in exactly the way you would expect them to: by screaming, wailing, and fighting in vain for what little remains of their lives.

After the boiling, their hides are ripped from their sometimes still breathing bodies and they are then carved up piece by piece, each bloody morsel wrapped in plastic, as Nature intended. The pieces are then placed into a refrigerated truck and shipped to a supermarket near you. It is there, under the fluorescent lights, that consumers purchase the corpses piecemeal, take them home to their families, and eat them, thus bringing the glorious cycle to its magnificent conclusion.

Only in the most Orwellian, Kafka-esque dystopia could such a system be considered “natural” or in accordance with anything that resembles the natural order.

Your argument is invalid.

http://www.nda.agric.za/docs/Infopaks/breeding.htm

http://www.blackmouthcur.com/HA02.htm

This argument is a favorite among people who believe that reading a snappy, clickbait headline from a pop-science article is equivalent to possessing genuine and unalterable scientific knowledge, which of course it is not. And while it is true that some respected scientists have posited the theory that the switch to a calorie-rich, meat-based diet on the part of our early ancestors enabled the human brain to grow more rapidly than it had at any other point in our evolution, it is not the only theory that can account for the rapid growth, and more recent research indicates that it is probably not the best theory either. According to a study published in the Quarterly Review of Biology, it wasn't the consumption of meat, but of cooked, starchy vegetables that enabled the rapid acceleration in the development of the human brain approximately 800,000 years ago.*

But I am not here to argue the scientific merits of the “starchy foods gave early humans larger brains” theory, compelling though it is. That question is up to scientists to settle, and I am no scientist. The point worth emphasizing is that regardless of how much it may have benefited our species, what our ancestors ate 800,000 years ago should not determine how, what, or whom we eat in the 21st century. The diet of early humans is no more relevant to the ethics of modern eating than the clothing of early humans is to the ethics of modern fashion. And just because something might have been beneficial or even necessary at some point in the distant past does not make it morally justifiable in the present.

For example, there is a consensus among all decent, thinking people that slavery is bad, but it cannot be denied that had it not been for slavery, the early American economy would not have flourished as it did. But what sane and sober person would dare suggest that because slavery was beneficial to the American economy in the past, we should re-institute today? Likewise, rape, murder, theft, and genocide have allowed some human communities to prosper in the past, but that does not justify continuing those practices in the present.

The same logic applies to what our ancestors ate. Even if it could be determined with 100% certainty that eating meat enabled the early human brain to grow to its present dimensions and complexity, it would not in any way imply that the practice of eating meat is necessary or justifiable for modern Homo sapiens.

Your argument is invalid.

*I use the term "human" here to refer to archaic humans, the ancestors of modern H. sapiens. According to the best current estimates, anatomically modern humans did not emerge until about 300,000 years ago. 

See also Humans Have Always Eaten Meat! and Animals Were Put Here To Be Eaten!

Further reading: Meat Logic: Why Do We Eat Animals? by Charles Horn

Purely anecdotal accounts of the My Grand-Mother Ate 40 Pounds of Bacon Every Day of Her Life And She Lived To Be 120! variety do not in any way constitute legitimate evidence for the claim that meat-eating is healthy. Even less do such claims (assuming that they are true) imply that veganism is unhealthy. And even less still can they hope to undermine the philosophical justification for veganism. In any conversation about the effects of diet on human health, what must be taken into account is the broader range of controlled scientific study and statistical analysis. Considered within those contexts, the evidence very clearly suggests that a whole foods, plant-based diet is quite conducive to optimal human health and that eating animals and the products derived from them is associated with an increased risk of heart disease, cancer, diabetes, obesity, high blood pressure, and many other bodily ailments.

[Editor's note: In the two excerpts that follow, the term “vegetarian” is used to refer to an entirely plant-based diet, which is to say, a vegan diet. In strict usage, the terms “vegan” and “vegetarian” have two quite distinct meanings, but historically, the term “vegetarian” has been (and continues to be) employed by many to connote a diet that excludes all products derived from animals. In the contemporary vernacular, however, a vegan diet excludes all products derived from animals, whereas a vegetarian diet excludes meat, but permits the consumption of dairy, eggs, and honey.]

In an article entitled "Vegetarian Diets: What Are The Advantages?" published in Forum of Nutrition in 2005, Dr. Claus Leitzmann wrote,

A growing body of scientific evidence indicates that wholesome vegetarian diets offer distinct advantages compared to diets containing meat and other foods of animal origin. The benefits arise from lower intakes of saturated fat, cholesterol and animal protein as well as higher intakes of complex carbohydrates, dietary fiber, magnesium, folic acid, vitamin C and E, carotenoids and other phytochemicals. ... In most cases, vegetarian diets are beneficial in the prevention and treatment of certain diseases, such as cardiovascular disease, hypertension, diabetes, cancer, osteoporosis, renal disease and dementia, as well as diverticular disease, gallstones and rheumatoid arthritis.

In 2010, the tree-hugging lefties over at the United States Department of Agriculture published the following statement in Dietary Guidelines for Americans:

In prospective studies of adults, compared to non-vegetarian eating patterns, vegetarian-style eating patterns have been associated with improved health outcomes – lower levels of obesity, a reduced risk of cardiovascular disease, and lower total mortality. Several clinical trials have documented that vegetarian eating patterns lower blood pressure.

On average, vegetarians consume a lower proportion of calories from fat (in particular, saturated fatty acids), fewer overall calories; and more fiber, potassium, and vitamin C than do non-vegetarians. In general, vegetarians have a lower body mass index. These characteristics and other lifestyle factors associated with a vegetarian diet may contribute to the positive health outcomes that have been identified among vegetarians.

The health benefits of a vegan diet having been sufficiently, or at least credibly, established, let's return to exposing the fallaciousness of the original argument. As mentioned above, within the realm of scientific inquiry, personal anecdotes are not tantamount to evidence for the truth or falsehood of a proposition. Statistically, not all people who smoke cigarettes will develop lung cancer, but that does not mean that smoking cigarettes does not cause lung cancer. What is relevant in extrapolating the relationship between cigarette smoking and lung cancer is the percentage of smokers among those who do develop lung cancer. This percentage is known to be quite high, which (all other things being equal) indicates a correlation between the the habit of smoking and the development of cancer. This correlation has been established in numerous peer-reviewed studies around the world.

The fact that a certain, and even significant, percentage of people who smoke cigarettes do not develop lung cancer does not indicate that smoking is (to use a slightly awkward construction) not unhealthy. Nor should the fact that some non-smokers also develop lung cancer lead anyone to conclude that not smoking cigarettes does not decrease the likelihood of developing cancer. What's important are statistical averages derived from the analysis of legitimate experimental data, and not the outcomes of isolated cases.

Likewise with eating animals. A person may be able to eat animals and animal by-products and not succumb to heart disease, colon cancer, high blood pressure, Type 2 diabetes, and a host of other ailments associated with the consumption of meat, eggs, and dairy. But such a case does not undermine the numerous peer-reviewed, multi-year, epidemiological studies that indicate a correlation between eating meat, eggs, and dairy and the development of the “diseases of affluence”.

Your argument is invalid.

Here we have a classic example of arguing Ad Hominem, a tactic often used within the realm of politics, but by no means limited to it. When arguing Ad Hominem (which literally means “to the man”) the idea is to undermine your opponent's position by attacking the character of those who espouse it, rather than addressing the merits of the position itself.

The intention of the I Once Saw A Vegan Wearing Leather Shoes! argument is to cast doubt upon the entire premise of veganism by attempting to expose the hypocrisy or inconsistency (apparent or actual) of at least one vegan. This is of course ridiculous. The arguments for veganism stand or fall on their own merits and are neither supported nor undermined by the personal habits or integrity of those who embrace, or purport to embrace, the philosophy.

This argument is even more tenuous in light of the fact that many convincing, cruelty-free alternatives to leather now exist and even from a close distance, they are all but indistinguishable from the (so to speak) genuine article. How anyone could make a cursory examination of someone else's footwear and determine conclusively the material out of which it was made is something of a mystery, but this is nonetheless the claim. As explained above, however, even if the observation were accurate, it would say nothing at all about the case for animal rights, animal liberation, and veganism.

Your argument is invalid.

The implications of this line of reasoning are not apparent at first blush. Does the person making the argument wish to imply that vegetarianism leads to National Socialism, or that National Socialism leads to vegetarianism? Perhaps we are to infer that because Hitler supposedly loved animals, we have a moral obligation to hate them? Whatever the implication might be, it's clear that the assertion that Hitler was a vegetarian is a brazen attempt to Poison The Well of abstinence from animal foods by associating the practice with the most reviled, but by no means the most murderous (that distinction goes to the meat-eating Joseph Stalin), man of the twentieth century.

Even if it could be proved that Hitler had been a vegetarian, the fact would say nothing at all about the underlying tenets of veganism. And in any case, the claim appears to be quite untrue. According to Robert Payne, who wrote what is considered by many, the definitive biography of Adolf Hitler, the Fuhrer had a well-attested fondness for Bavarian sausage, caviar, cream, eggs, and stuffed squab. In no sense of the word “vegetarian” (to say nothing of “vegan”) are sausage, caviar, and squab permissible.

The notion that Hitler was a vegetarian was a gross fabrication conceived and promulgated by his minister of propaganda, Joseph Goebbels, who wanted Hitler to be seen as an ascetic, a paragon of self-restraint, a man invulnerable to the myriad temptations of the flesh, who did not drink alcohol, smoke cigarettes, consort with women, or eat meat. While there is apparently no evidence to suggest that Hitler ever smoked, there is also no question that he drank alcohol, kept the company of women, and regularly ate meat and other animal by-products.

From Payne's book, The Life and Death of Adolf Hitler:

Hitler's asceticism played an important part in the image he projected over Germany. According to the widely believed legend, he neither smoked nor drank, nor did he eat meat or have anything to do with women. Only the first was true. He drank beer and diluted wine frequently, had a special fondness for Bavarian sausages and kept a mistress, Eva Braun, who lived with him quietly in the Berghof. There had been other discreet affairs with women. His asceticism was fiction invented by Goebbels to emphasize his total dedication, his self-control, the distance that separated him from other men. By this outward show of asceticism, he could claim that he was dedicated to the service of his people.

The fact that over six decades after his death, many people still believe the fictitious details of Hitler's public persona testifies to the effectiveness of Goebbels' propagandizing. But the mere persistence of a lie does not bestow any measure of truth upon it. Even less does it undermine the ethical or moral justification of the philosophy around which the lie is centered.

Your argument is invalid.

Sources:

http://www.vegsource.com/berry/hitler.html

http://www.vegsource.com/berry/hitler_book.htm

Robert Payne, The Life and Death of Adolf Hitler (New York: Praeger, 1973), pp. 346-7.

As difficult as it sometimes is to give the benefit of the doubt to those who argue against veganism, it becomes almost impossible to do so when they marshal this ludicrous argument in defense of eating animals. The underlying assumption seems to be that eating meat is either, a) a type of preemptive strike against the animals, a self-defense tactic of sorts, or, b) an act of retribution for the horrible crimes that these vicious and blood-thirsty lambs, chickens, goats, and cows would have committed against H. sapiens, had they only been given the chance. Of course, nothing could be more absurd. Let's first examine the claim being made and then consider its moral implications.

The vast majority of the tens of billions of nonhuman animals who are bred into existence for the sole purpose of being slaughtered and eaten by humans every year are gentle, docile creatures who pose no threat whatsoever to people. Cows, for instance, are indeed large and powerful enough to harm a person, but they show no interest in doing so, except when provoked or threatened, and even then, they very often exhibit tremendous restraint. Additionally, cows are herbivores, which means they couldn't eat a human being even if they wanted to. Nothing about the physiology of cows would enable them to metabolize human flesh, and they seem to know it. This helps explain why, after thousands of years of co-existing with humans and literally billions of opportunities to attack and devour them, there is no reliable or credible record of any cow anywhere ever killing and eating a human being. They've been patiently munching away on grass and other forage for eons, and nothing about their behavior suggests that they are interested in making the change to a carnivorous or omnivorous diet.

And the same applies to lambs and sheep, but with the added consideration that these gentle, herbivorous animals are much smaller than cows, making them even less dangerous still. Anyone who believes that a lamb or sheep could not only kill and eat a human, but also would do so if given the chance, has clearly not spent any time around these incredibly gentle and affectionate animals. A single afternoon at any reputable farmed animal sanctuary will completely dispel this ridiculous and unsupported notion.

But what about the notoriously ravenous Gallus gallus domesticus, or, as this savage beast is more commonly known, the chicken? Surely, this dangerous and formidable creature, with his legendary thirst for human blood and insatiable appetite for human flesh is an urgent threat to human beings, right? Actually, not so much. Seldom weighing more than seven pounds and possessing no anatomical features, such as fangs or claws, that could possibly be lethal to a human being, these animals could not conceivably kill and eat a person. Unlike their herbivorous brothers and sisters, cows, sheep, and lambs, chickens do include meat in their diets, in the form of small snakes, lizards, mice, and insects; but this habit does not render them a threat to humans. And in point of fact, their gentle disposition, inquisitive nature, and relative intelligence make chickens excellent animal companions, as many people have discovered by adopting them, and as many sanctuary workers and visitors can attest.

Ignoring all of the evidence to the contrary, however, let's assume for the sake of argument that farmed animals would kill and eat human beings if given the chance. Would that justify our killing and eating them? Hardly. If you had the opportunity to steal money from someone who you knew would do the same to you if given the chance, would that make the act of stealing ethically defensible? Of course not. It makes no sense to punish someone for the things that you think they would do, or would have done, if given the chance. There's a reason that the Golden Rule is “Do unto others as you would have others do unto you,” and not, “Do unto others before they do unto you.” And the same applies to our treatment of animals. In fact, it applies even more, because the animals we breed into existence for food do not represent a legitimate threat to us. And even if they did represent a threat to us, the obvious solution would be to stop breeding them into existence in the first place.

And finally, if you're the type of person who disparages vegans for being weak, but you're frightened that a rabbit, turkey, or chicken could literally kill you, then you need to do some serious reflecting on the meaning of the word “weakness”.

Your argument is invalid.

See also But If We Don't Kill And Eat Them, They'll Eat All The Food We Need To Survive! and But Lions Eat Meat!

This feckless bit of casuistry combines the classic Non Sequitur with a textbook False Dichotomy. The Non Sequitur aspect of the argument is the baseless insinuation that anyone who chooses to spend his or her time doing anything for the benefit of non-human animals must therefore be indifferent to the needs and suffering of his or her fellow human beings. The False Dichotomy element of the argument is the equally baseless assumption that helping animals and helping humans are, in some unspecified way, two mutually exclusive activities.

The notion that an act of kindness toward an animal (such as not eating her) must necessarily occur at the expense of, say, the homeless or the world's hungry is a logically untenable claim, but what makes this argument so completely laughable is not the rhetorical double-whammy of combining two logical fallacies into one irrelevant assertion, but the inescapable fact that going vegan does more for the environment and for the cause of social justice than any single action a person can take.

For instance, there appears to be no disagreement that world hunger is a grave and terrible problem. Every day on this planet, 100,000 people –16,000 of them children– die from starvation. An additional one billion people suffer from malnutrition. Who could fail to be outraged by such a horrible tragedy? This is relevant to veganism because according to the American Journal of Clinical Nutrition, the amount of grain fed to livestock in the U.S. every year could feed about 840 million people, roughly eleven times the number of people who annually die of starvation worldwide. By refusing to support the practice of industrial or any other kind of animal agriculture and the gratuitous misappropriation of resources involved with it, vegans do a great deal to combat world hunger.

And consider the following statistics about the global animal by-product industry and its effect on people and the environment:

• According to scientists at the World Bank, animal agriculture is responsible for over 50 percent of anthropogenic greenhouse gases (AGHG) produced world-wide, making animal agriculture responsible for more AGHG than all forms of transportation combined and tripled.
• Animal agriculture is responsible for more deforestation that any other industry in the world.
• Animal agriculture uses more fresh water than any other industry in the world, which contributes to water scarcity.
• Animal agriculture is the world's largest polluter of fresh water.
• In the United States, on-the-job injuries among slaughterhouse workers are three times higher than in other factory jobs.
• And, according to a recent report by the United Nations, 70 percent of all diseases in humans are linked to animal agriculture.

So, if you want to be upset about the infuriating tendency of vegans to extend our compassion beyond our own species, that is of course your prerogative, but the simple and incontrovertible fact is that we are doing more to fight world hunger, water scarcity, deforestation, climate change, water pollution, and a host of other environmental calamities and social injustices than just about anyone else

Your argument is invalid.

Sources:

http://www-wds.worldbank.org/servlet/WDSContentServer/WDSP/IB/2004/02/02/000090341_20040202130625/Rendered/PDF/277150PAPER0wbwp0no1022.pdf

http://www.fao.org/docrep/019/i3440e/i3440e.pdf

See also: The Fallacy of Relative Privation

Of all the objections that otherwise rational people sometimes marshal against veganism, the But If We Don't Kill and Eat Them, They'll Eat All of The Food We Need to Survive! argument is the one that reflects the greatest disconnect with reality. That is of course not to say that all of those who make this ridiculous claim are themselves delusional, but the notion that human beings as a species are somehow competing with farmed animals for the means to survive is as far from reality as it could conceivably be.

I can't help wondering if the proponents of this argument actually believe that if not for the diligence of the global factory farming industry, the world would be immediately overrun by the ravenous cows, pigs, turkeys, and chickens who they believe are pushing at the gates of their CAFOs in a sinister effort to escape from their confines, overpopulate the globe, and ruthlessly drive Homo sapiens to extinction. Do the proponents of this argument feel indebted to the selfless and heroic employees of the world's multinational agribusiness corporations who they believe are the only thing that stands between the human race and a calamitous rebellion of the world's farm animals? Perhaps they believe that it's "us against them" and if we fail to slaughter and eat them by the billions, it's only a matter of time before they are at our doorsteps and devouring every morsel of food they can get their insatiable mouths (and beaks) on.

The fallaciousness of this argument is anything but subtle. The world's tens of billions of chickens, cows, pigs, geese, goats, ducks, and turkeys are almost entirely the products of human efforts. They exist in such enormous numbers for no other reason than that they have been produced by human beings in a system of large-scale exploitation. These animals are forcibly bred by artificial insemination and are brought into the world, generation after generation, for the sole purpose of placating the gastronomic preferences of human beings.

Yes, they consume enormous quantities of grain, forage, and water in the course of their brief and miserable lives, but they consume only what they are fed by human beings; and the fact that 70 percent of all fresh water and an equal percentage of all the arable land on the planet are dedicated to animal agriculture is not to be blamed on the animals, but on the human beings who continue to misappropriate and mismanage the world's dwindling natural resources in such an unconscionable and unsustainable way.

Your argument is invalid (and actually quite stupid).

One afternoon a couple of years ago, I was walking down the sidewalk in Manhattan, wearing a t-shirt with the words “For The Animals” printed across the front. A short, surly man stopped me and asked if I thought it was wrong to use horses for carriage rides. I replied that of course I think it's wrong and that no animal should be forced to pull a heavy carriage around the busy and dangerous streets of New York City, or for that matter, any city. He responded belligerently that he himself was a carriage driver and if what he was doing were wrong, then how do I explain the fact that he hasn't been arrested and thrown in jail?

This man was attempting to perpetrate the Legalistic Fallacy: a logical fallacy that occurs when one assumes that A) If a particular practice is legal, then it must therefore be moral, and the corollary, that B) Any practice that is not illegal is therefore not immoral.

This absurd fallacy can be refuted by the simple act of citing historical examples of moral atrocities that have been not merely sanctioned by the state, but perpetrated by it: The Holocaust, the African slave trade, the genocide of indigenous peoples on the North American, South American, and Australian continents, and refusing women the right to vote are just a few examples from a veritable litany of moral obscenities that were not only completely legal, but also perpetrated by the very governments who made the laws permitting them.

The simple fact is that legislative bodies such as those found in governments are not legitimate arbiters of right and wrong and their laws frequently do not reflect what is moral for society, but merely what is advantageous and expedient for the ruling class.

Your argument is invalid.

A common tactic among those who find themselves losing an argument with a vegan is to attempt to undermine their opponent's moral authority by asking, "Who are you to judge?!" In this way, they hope to put an abrupt end to what may be an uncomfortable conversation, or, failing that, at least to change the subject. And though the tactic itself generally amounts to nothing more than a facile and transparent diversion, the question is worth treating seriously and should begin by defining the key term, “to judge”. Thankfully, that work has already been done for us! As it happens, there's an entire industry devoted to defining words. The Oxford Dictionary of American English defines “to judge” simply as, “to form an opinion or conclusion about”. So, the original question could be re-stated as, “Who are you to form an opinion?!” to which one reply might be, “Who are you to decide who gets to form an opinion?” But, as is often the case, taking the question at face value can be a more effective means of exposing the vacuousness of your interlocutor's position.

Who am I to judge, you ask? In short, I am a moral agent and a rational human-being capable of making the important distinction between right and wrong, good and bad, selfish and benevolent. Judgement forms the basis of all legal systems and all codes of morality and yet, the words "Don't judge me!" have become the first resort of many people who don't want their behavior questioned by others. But certainly, the majority of people wouldn't hesitate to "judge" a person who, for instance, abused puppies or poisoned children. It is nothing if not judgmental to say that abusing puppies and poisoning children are bad and if any person guilty of such behavior had nothing to say in his own defense but "Don't judge me!" we would rightly dismiss his insistence that we are not entitled to assign a moral value to his actions. Of course we are. And the same applies to those who support the exploitation, oppression, and slaughter of animals. I have as much right to assign a moral value to that abominable practice as you have to assign a moral value to abusing puppies and poisoning children, or, for that matter, that anyone has to assign a moral value to feeding the poor and aiding the sick. (It's funny how no one ever objects to being “judged” when the “judgement” is favorable.)

Starting from first principles, if we accept as axiomatic (as I think we must) that oppression, exploitation, and cruelty are bad, then it naturally and inevitably follows that we shouldn't support or perpetuate these practices. And if we allow the words “Don't judge me!” and "Who are you to judge?" to provide a moral safe haven for those who choose to support the oppression and exploitation of, and cruelty to the world's billions of non-human animals used for food, clothing, experimentation, and entertainment, then we must grant the same impunity to those who abuse puppies, poison children, or for that matter, commit any other atrocity whatsoever. To grant this impunity would be to surrender to the worst kind of anarchy and moral cowardice. We could establish and enforce no laws and impose no standard of behavior on society. That is not a world in which I care to live, regardless of who feels "judged" as a result. There are many things much more important than not upsetting other people and two of those things are speaking on behalf of the innocent and defenseless and calling things by their true names.

Your argument (in my judgment) is invalid.

This is an argument against veganism that, thankfully, seems to have waned in popularity in recent decades, but is still sometimes advanced by those dogmatically speciesist and vehemently anti-vegan types who are not afraid to sacrifice accuracy or forfeit respectability in order to defend their ideology. What lies at the root of this line of reasoning is the absurd assumption that someone's intelligence is somehow a legitimate criterion for moral consideration and that those who fall below a certain intelligence threshold are ipso facto unworthy to be included in the moral universe of those who have declared by fiat that they are smarter than the rest of the animal kingdom.

Despite my best efforts to comprehend this position, I have never understood why anyone would think that intelligence is a legitimate criterion for moral consideration. It strikes me as a complete non sequitur. Where the right to avoid unnecessary suffering is concerned, one's degree of intelligence is almost as irrelevant and arbitrary a criterion as one's means of locomotion, sleeping habits, or lung capacity. If intelligence is the sine quo non for moral consideration, then what status should we confer upon those millions of developmentally disabled Homo sapiens whose intelligence will never surpass that of a full-grown elephant, chimpanzee, or dolphin? If one accepts that intelligence is the magic ticket into the world of moral consideration, then cognitively impaired human beings should be fair game for anyone who is inclined to objectify, commodify, exploit, or enslave them. And yet, this obvious implication of the “dumb animals” argument is never conceded by those who claim that an animal's intelligence should determine his or her legitimacy as an object of moral consideration.

Another obvious flaw in this assertion is the inarguable fact that many non-human animals are not dumb at all. Ravens and crows are remarkably clever creatures, as are many parrots, cephalopods, cetaceous mammals, and great apes. And with respect to intelligence, most people don't give so-called "farm" animals nearly enough credit either. A common myth concerning domesticated turkeys is that when it rains, they will look up in utter fascination, beaks agape, and drown as a result. There's not a shred of truth to this filthy slander against turkeys and the myth is thoroughly debunked by the sensible folks at Snopes.

And the intelligence of pigs and chickens is also greatly under-rated. An adult pig is smarter than a three year-old human child and some chickens have displayed the ability to perform arithmetic. So, the "dumb animals" argument fails on at least two fronts: first, by establishing intelligence as an arbitrary and irrelevant criterion for moral consideration, and second, by failing to recognize (or simply ignoring the fact) that human beings do not have a monopoly on intelligence.

I will give the last word on this subject to the late British philosopher Jeremy Bentham, who exposed the callowness of the “dumb animals” argument exquisitely in his 1789 treatise, Introduction to the Principles of Morals and Legislation:

The French have already discovered that the blackness of the skin is no reason a human being should be abandoned without redress to the caprice of a tormentor. It may one day come to be recognised that the number of the 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 of discourse? But a full-grown horse or dog, is beyond comparison a more rational, as well as a more conversable animal, than an infant of a day or a week or even a month, old. But suppose the case were otherwise, what would it avail? The question is not, Can they reason? nor, Can they talk? but, Can they suffer?

Correction: Bentham gets the penultimate word. For the sake of consistency, the final word goes to me: Your argument is invalid.

See also Animals Were Put Here To Be Eaten! and The Bible Says We Should Eat Meat!

Like so many logical fallacies, this line of attack against veganism has a charming Latin name: "Tu Quoque", which means “You also” or “You're another (person who does awful things)”. And although field mice are a favorite object of concern among the opponents of veganism, these delightful creatures by no means have a monopoly on their affections. In fact, no life-form is too small to elicit the feverish concern of those who marshal this argument and whose compassion is so far-reaching that it often extends even to bacteria, which–they are eager to point out–vegans callously exterminate en masse whenever they eat.

As with the I Once Saw A Vegan Wearing Leather Shoes! (non)argument against veganism, the intention of the Tu Quoque response is to undermine the moral authority of the person making the case, while completely and conveniently side-stepping the position he or she is actually advancing. After all, if one's opponent can be exposed as a callow hypocrite, then what more needs to be discussed, right? Well, kind of a lot, as it turns out.

It is the intention of most vegans to cause as little harm and as little suffering as possible to all sentient beings, including field mice. That some measure of harm will result from some of our choices is practically unavoidable. What the vegan concerns herself with, however, is minimizing that harm as much as she can by making choices that don't require that animals be enslaved, exploited, and slaughtered. If those choices do involve harm to or the suffering of other beings, such harm or suffering is incidental, and not intentional. That is vastly different from making choices in which the suffering of and harm to non-human animals are intrinsic elements, as they are in the production of meat. One cannot eat the muscles and organs of non-human animals without first removing them from that animal's body, a process that obviously and invariably requires the slaughter and dismemberment of that animal.

Contrariwise, there is nothing in the harvesting of potatoes or other edible plants that requires the sacrifice of field mice, or boll weevils, or aphids, and any harm done to them in the process of cultivation (although regrettable) is not an intrinsic or necessary element of the process itself. Such is demonstrably not the case with the killing and eating of animals, and any attempt to represent the two practices as morally equivalent is therefore wholly unjustified. And it is unjustified not just on the grounds of the vast difference of intentionality of the vegan versus that of the non-vegan, but also on the purely practical grounds that the production of meat, eggs, and dairy requires enormous quantities of grain and forage.

The production of just one pound of beef, for instance, requires sixteen pounds of grain. Producing one pound of pork requires six pounds of grain. If we accept the premise of the Tu Quoque argument against veganism, then it follows that the person who consumes an animal must also assume the additional moral responsibility of any animals harmed or killed in the harvesting of the plants required to feed that animal. It is therefore inarguable that whatever minimal harm might be done as an indirect result of a human diet that consists entirely of plants amounts to a tiny fraction of the harm done by a diet that includes animals, who must themselves be fed quantities of plants far greater than what even the most ravenous vegan could be expected to consume.

Your argument is invalid.

See also Plants Have Feelings, Too! and Who Are You To Judge?!

"What about these?" says the mighty Homo sapien, pointing triumphantly to the tiny canine teeth inside his mouth, “Don't these prove that humans are supposed to eat meat?” I call this the Argument Ad Caninum, a defense of meat-eating that is as tiresome as it is irrelevant. The logic implicit in this assertion seems to be the following: Animals who are unambiguously carnivorous, such as lions, wolves, and cheetahs, have canine teeth and they eat meat. The mouth of the Homo sapien is also equipped with canine teeth. Therefore, humans should eat meat!

The Ad Caninum argument is a logical fallacy based on a fundamental misunderstanding of both physiology and evolution. For starters, the canine teeth of lions and other carnivores are nothing like the so-called canine teeth of humans. I say "so-called" because the canine teeth of Homo sapiens are so unlike the true canine teeth of carnivores that ours are Canines In Name Only (CINOs).

The canine teeth of true carnivores are long, sharp, and curved. They are formidable blades inside the mouth exquisitely evolved for killing and eating prey. The CINOs of humans, on the other hand, are short, blunted, and are thoroughly unimpressive as evolutionary adaptations for killing and eating animals, but are remarkably well-adapted for breaking apart and eating all manner of fruits, nuts, seeds, roots, tubers, and the like. Our CINOs render us no more equipped for hunting, killing, and eating prey than our equally unimpressive fingernails, our comparatively weak jaw muscles, and our broad, flat incisors, all of which reflect our anatomical kinship to other frugivores.

And even if our CINOs were identical to those of true carnivores, it would not necessarily imply that we should eat animals, as the same anatomical trait can evolve in different species as an adaptation to different conditions. Our fellow frugivore, the Silverback gorilla, for instance, has evolved an impressive set of canine teeth which are used as a threat display to intimidate competitors and enemies, rather than as an aid to killing prey. Similarly, a bird's feathers can serve as either an aid to flying (as in the case of the eagle, heron, and other birds who fly), or as thermo-regulating devises among flightless birds, such as penguins.    

The best response I have yet read to the Argument Ad Caninum is from the American physician and author John A. McDougal, M.D., who sums up the matter thus:

Our dentition evolved for processing starches, fruits, and vegetables, not tearing and masticating flesh. Our oft-cited "canine" teeth are not at all comparable to the sharp teeth of true carnivores. I lecture to over 10,000 dentists, dental hygienists, and oral specialists every year, and I always ask them to show me the "canine" teeth in a person’s mouth – those that resemble a cat’s or dog’s teeth – I am still waiting to be shown the first example of a sharply pointed canine tooth.

Your argument is invalid.

Sources:

http://www.scribd.com/doc/94656/The-Comparative-Anatomy-of-Eating

http://www.nealhendrickson.com/mcdougall/030700pumeatinthehumandiet.htm

http://michaelbluejay.com/veg/natural.html

https://en.wikipedia.org/wiki/Canine_tooth

https://en.wikipedia.org/wiki/Flightless_bird

Protein deficiency in developed nations is very much like voter fraud in the United States. Some people love to fret about it endlessly and in the most strident fashion, but when pressed to give an instance of it actually happening, they are embarrassingly short on details. The simple fact is that if you're getting enough calories, then you are almost certainly getting enough protein. And with vegans making up seven percent of the U.S. population, if there were any correlation between a plant-based diet and protein deficiency, we would certainly know about it by now.

According to the Institute of Medicine, the daily protein requirement for an average adult is 0.8 grams for every kilogram of body weight. That amounts to fifty-six grams of protein a day for men and forty-six grams for women. The average daily consumption of protein for both men and women, however, is considerably higher than the recommended daily intake: on average, U.S. men over the age of twenty consume over ninety-eight grams of protein, while women over twenty average sixty-eight grams of protein per day. So, there is not a deficiency, but a positive surplus of protein in the American diet and that excess protein doesn't do the human body any favors. Too much protein in the diet can lead to kidney damage, dehydration, and weight gain and when the protein is in the form of meat, eggs, and dairy, the health consequences are often far more severe, numerous, and frequent and include diabetes, cardiovascular disease, obesity, and cancer.

So the next time a non-vegan asks you the inevitable question “Where do you get your protein?” consider responding with something other than the standard and rote list of protein-rich plant foods and reply instead with a question of your own. “You mean, how do I manage not to get too much protein and avoid the health risks associated with it? You'd be surprised at how easy it is when you don't eat animals. And because you seem to have an interest in nutrition, perhaps you won't mind my asking where you get your fiber, anti-oxidants, and micro-nutrients.”

It is at that point in the conversation that you can expect your opponent to speculate aloud on the ability of asparagus to feel pain.

Your argument is invalid.

Sources and further reading:

http://www.huffingtonpost.com/2014/06/12/eating-too-much-protein_n_5481307.html?utm_hp_ref=mostpopular

The China Study by T. Colin Campbell

Diet for a New America by John Robbins

http://advance.uconn.edu/2002/020429/02042904.htm

http://www.webmd.com/diet/news/20020422/high-protein-diets-cause-dehydration

http://www.iom.edu/Activities/Nutrition/SummaryDRIs/~/media/Files/Activity%20Files/Nutrition/DRIs/5_Summary%20Table%20Tables%201-4.pdf

http://www.eatright.org/about/content.aspx?id=8357

http://www.publicpolicypolling.com/main/2013/02/food-issues-polarizing-america.html

The Desert Island argument is a ubiquitous late-game strategy for those who have exhausted or nearly exhausted their case against veganism and it generally goes like this, “Okay, vegan. I get that eating animals is bad for the environment, bad for people's health, and bad for the animals, but are you telling me that if you were stranded on a desert island and you had nothing to eat but pigs-in-a-blanket and wild grouse, you would rather starve?” The intention of this argument is to call into question the strength of the vegan's moral convictions by suggesting that if she were given the choice between starvation and eating animals or animal by-products, she would abandon her vegan convictions and eat whatever or whomever she could get her protein-deprived hands on.

What underpins this argument is the ludicrous assumption that any ideal for which someone else is unwilling to die is somehow not worth taking seriously. And never mind that many vegans would rather die than take the life of another animal. What this argument also fails to acknowledge is the difference between killing as matter of pure necessity and killing as matter of convenience or pleasure, which are by no means morally equivalent. Killing as matter of survival (as only a small handful of subsistence hunters do) is a vastly different thing from killing for the sake of sensory pleasure or out of convenience.

A much more pertinent question (and one, incidentally, for which we can take no credit) is the following: Let's say that you, eater of meat, eggs, and dairy, were given a choice between two life-style alternatives. On the one hand, you could get all the nutrients and calories you need from a healthy, cruelty-free, vegan diet consisting of fruits, vegetables, and grains, all of which are readily available at almost any supermarket. On the other hand, you could subsist on a diet that necessitates cruelty, exploitation, and slaughter and which contributes significantly to climate change, deforestation, water scarcity, water pollution, ocean “dead zones”, habitat loss, species extinction, and world hunger.

Given these alternatives, which would you choose? Answer the latter question honestly and then try to ask the former with a straight face.

Your argument is invalid.

It is a near certainty that at some point in any discussion of the vegan life-style with a meat-eater, the word "Bacon!" will be invoked, as if the momentary sensory experience of eating bacon somehow constitutes a legitimate moral defense of or justification for the torment and slaughter of the pigs from whose bodies bacon is produced.

Of course "Bacon!" is no defense at all and amounts to nothing more than a transparent and futile attempt to justify cruelty, oppression, injustice, and exploitation of sentient beings on the morally untenable grounds that one derives a certain degree of sensory pleasure from the corpses of those who have been exploited, oppressed, and slaughtered and the cruelty is therefore justified. After all, doesn't the momentary gratification of a person's sense of taste matter more than the life of a pig? Of course it doesn't.

The assumption that a moment's sensory pleasure on the part of a human being somehow provides legitimate moral grounds for tormenting and slaughtering an innocent and defenseless non-human animal is best challenged by substituting the sense of taste with either the auditory or olfactory sense and replacing the pig with a puppy or kitten. Re-framing the argument in this way will expose the moral absurdity implicit in it.

For instance, if one were to defend the barbaric practice of killing kittens or puppies on the grounds that the sound or smell of such deplorable activity provided one with a terrific (albeit, brief) sense of gratification, one would rightly be considered a monster. But apply the exact same logic to the sense of taste, and substitute pigs for kittens and puppies, and all of a sudden, people are expected to treat the mere assertion as if it were in any sense an argument and not merely childish nonsense. The ability to recognize that some (indeed, most) things are more important than sensory pleasure, which is, in any case, always subject to diminishing returns, is indispensable for anyone who aspires to live a life that is not merely hedonistic. In other words, an important part of being a responsible and well-rounded person is recognizing that just because you enjoy something doesn't make it right.

Your argument is invalid.

Further reading:

http://www.amazon.com/Eating-Animals-Jonathan-Safran-Foer-ebook/dp/B002SSBD6W/ref=sr_1_fkmr1_3?s=books&ie=UTF8&qid=1401736712&sr=1-3-fkmr1&keywords=veganism+ethics+books+eating+meat

http://www.amazon.com/Love-Dogs-Pigs-Wear-Cows-ebook/dp/B005FFTEQQ/ref=pd_sim_b_2?ie=UTF8&refRID=06Z7PTBN2YKGMX92YRNR

http://www.amazon.com/Main-Street-Vegan-Healthfully-Compassionately-ebook/dp/B0072O01FQ/ref=pd_sim_b_4?ie=UTF8&refRID=06Z7PTBN2YKGMX92YRNR