Editing Peter Singer (section)

== Applied ethics ==
His most comprehensive work, ''Practical Ethics'',<ref>''Practical Ethics'', Cambridge: Cambridge University Press, 1979, ISBN 0-521-22920-0; second edition, 1993, ISBN 0-521-43363-0.</ref> analyzes in detail why and how beings' interests should be weighed. His principle of equality encompasses all beings with interests, and it requires equal consideration of those interests, whatever the species. The principle of equal consideration of interests does not dictate equal treatment of all those with interests, since different interests warrant different treatment. All have an interest in avoiding pain, for instance, but relatively few have an interest in cultivating their abilities. Not only does his principle justify different treatment for different interests, but it allows different treatment for the same interest when diminishing marginal utility is a factor, favoring, for instance, a starving person's interest in food over the same interest of someone who is only slightly hungry. 

Among the more important human interests are those in avoiding pain, in developing one's abilities, in satisfying basic needs for food and shelter, in enjoying warm personal relationships, in being free to pursue one's projects without interference, "and many others". The fundamental interest that entitles a being to equal consideration is the capacity for "suffering and/or enjoyment or happiness"; mice as well as human beings have this interest, but stones and trees do not. He holds that a being's interests should always be weighed according to that being's concrete properties, and not according to its belonging to some abstract group such as a species, or a set of possible beings, or an early stage of something with an as yet unactualized potential. He favors a 'journey' model of life, which measures the wrongness of taking a life by the degree to which doing so frustrates a life journey's goals. So taking a life is less wrong at the beginning, when no goals have been set, and at the end, when the goals have either been met or are unlikely to be accomplished. The journey model is tolerant of some frustrated desire, explains why persons who have embarked on their journeys are not replaceable, and accounts for why it is wrong to bring a miserable life into existence. Although sentience puts a being within the sphere of equal consideration of interests, only a personal interest in continuing to live brings the journey model into play. This model also explains the priority that Singer attaches to  ''interests'' over trivial desires and pleasures. For instance, one has an interest in food, but not in the pleasures of the palate that might distinguish eating steak from eating tofu, because nutrition is instrumental to many goals in one's life journey, whereas the desire for meat is not and is therefore trumped by the interest of animals in avoiding the miseries of factory farming. 

In order to avoid bias towards human interests, he requires the idea of an impartial standpoint from which to compare interests. This is an elaboration of the familiar idea of putting oneself in the other's shoes, adjusted for beings with paws or flippers. He has wavered about whether the precise aim is the total amount of satisfied interests, or instead the most satisfied interests among those beings who already exist prior to the decision one is making. Both have liabilities. The total view, for instance, seems to lead to Derek Parfit's Repugnant Conclusion<ref>See Derek Parfit, ''Reasons and Persons'', Oxford: Clarendon Press, 1984.</ref> — that is, it seems to imply that it's morally better to have an enormous population with lives barely worth living rather than a smaller population with much happier lives.  The prior-existence view, on the other hand, seems questionably indifferent to the harm or benefit one can do to those who are brought into existence by one's decisions. The second edition of ''Practical Ethics'' disavows the first edition's suggestion that the total and prior-existence views should be combined in such a way that the total view applies to sentient beings who are not self-conscious and the prior-existence view applies to those who are. This would mean that rats and human infants are replaceable — their painless death is permissible as long as they are replaced — whereas human adults and other persons in Singer's expanded sense, including great apes, are not replaceable. The second edition dispenses with the requirement of replacement and the consequent high population numbers for sentient beings. It asserts that preference-satisfaction utilitarianism, incorporating the 'journey' model, applies without invoking the first edition's suggestion about the total view. But the details are fuzzy and Singer admits that he is "not entirely satisfied" with his treatment of choices that involve bringing beings into existence.

Ethical conduct is justifiable by reasons that go beyond prudence to "something bigger than the individual," addressing a larger audience. Singer thinks  this going-beyond identifies moral reasons as "somehow universal", specifically in the injunction to 'love thy neighbor as thyself', interpreted by him as demanding that one give the same weight to the interests of others as one gives to one's own interests. This universalizing step, which Singer traces from Kant to Hare, is crucial and sets him apart from moral theorists from Hobbes to David Gauthier, who regard that step as flatly irrational. Universalization leads directly to utilitarianism, Singer argues, on the strength of the thought that my own interests cannot count for more than the interests of others. Taking these into account, one must weigh them up and adopt the course of action that is most likely to maximize the interests of those affected; utilitarianism has been arrived at. Singer's universalizing step applies to interests without reference to who has them, whereas a Kantian's applies to the judgments of rational agents (in Kant's kingdom of ends, or Rawls's Original Position, etc.). Singer regards Kantian universalization as unjust to animals. It's their capacity for suffering/happiness that matters morally, not their deficiency with respect to rational judgment. As for the Hobbesians, Singer attempts a response in the final chapter of ''Practical Ethics'', arguing that self-interested reasons support adoption of the moral point of view, such as 'the paradox of hedonism', which counsels that happiness is best found by not looking for it, and the need most people feel to relate to something larger than their own concerns.

=== Abortion, euthanasia and infanticide ===
Consistent with his general ethical theory, Singer holds that the right to physical integrity is grounded in a being's ability to suffer, and the right to life is grounded in, among other things, the ability to plan and anticipate one's future. Since the unborn, infants and severely disabled people lack the latter (but not the former) ability, he states that abortion, painless infanticide and euthanasia can be justified in certain special circumstances, for instance in the case of severely disabled infants whose life would cause suffering both to themselves and to their parents. 

In his view the central argument against abortion is ''It is wrong to kill an innocent human being; a human fetus is an innocent human being; therefore it is wrong to kill a human fetus''. He challenges the second premise, on the grounds that its reference to human beings is ambiguous as between human beings in the zoological sense and persons as rational and self-conscious. There is no sanctity of human life that confers moral protection on human beings in the zoological sense. Until the capacity for pain develops after "18 weeks of gestation", abortion terminates an existence that has no intrinsic value (as opposed to the value it might have in virtue of being valued by the parents or others). As it develops the features of a person, it has moral protections that are comparable to those that should be extended to nonhuman life as well. He also rejects a backup argument against abortion that appeals to potential: ''It is wrong to kill a potential human being; a human fetus is a potential human being; therefore it is wrong to kill a human fetus.'' The second premise is more plausible, but its first premise is less plausible, and Singer denies that what is potentially an X should have the same value or moral rights as what is already an X. Against those who stress the continuity of our existence from conception to adulthood, he poses the example of an embryo in a dish on a laboratory bench, which he calls Mary. Now if it divides into two identical embryos, there is no way to answer the question whether Mary dies, or continues to exist, or is replaced by Jane and Susan. These are absurd questions, he thinks, and their absurdity casts doubt on the view that the embryo is a human being in the morally significant sense.

Singer classifies euthanasia as voluntary, involuntary, or non-voluntary. (For possible similar historical definitions of euthanasia see Karl Binding, Alfred Hoche and Werner Catel.) Given his consequentialist approach, the difference between active and passive euthanasia is not morally significant, for the required act/omission doctrine is untenable; killing and letting die are on a moral par when their consequences are the same. Voluntary euthanasia, undertaken with the consent of the subject, is supported by the autonomy of persons and their freedom to waive their rights, especially against a legal background such as the guidelines developed by the courts in the Netherlands. Non-voluntary euthanasia at the beginning or end of life's journey, when the capacity to reason about what is at stake is undeveloped or lost, is justified when swift and painless killing is the only alternative to suffering for the subject.

=== World poverty ===
In "Famine, Affluence, and Morality",<ref>"[http://www.utilitarian.net/singer/by/1972----.htm Famine, Affluence, and Morality]", ''Philosophy and Public Affairs'', vol. 1, no. 1 (Spring 1972), pp. 229-243.</ref> one of Singer's best-known philosophical essays, he argues that the injustice of some people living in abundance while others starve is morally indefensible. Singer proposes that anyone able to help the poor should donate part of their income to aid poverty and similar efforts. Singer reasons that, when one is already living comfortably, a further purchase to increase comfort will lack the same moral importance as saving another person's life. Singer himself donates 20% of his salary to Oxfam and UNICEF. In "Rich and Poor", the version of the aforementioned article that appears in the second edition of ''Practical Ethics'',<ref>''Op. cit.'', pp. 218-246.</ref> his main argument is presented as follows: ''If we can prevent something bad without sacrificing anything of comparable significance, we ought to do it; absolute poverty is bad; there is some poverty we can prevent without sacrificing anything of comparable moral significance; therefore we ought to prevent some absolute poverty.''

=== Other views ===
====Zoophilia====
In a 2001 review of Midas Dekkers's ''[[Dearest Pet: On Bestiality]]'',<ref name="heavy">"[http://www.nerve.com/Opinions/Singer/heavyPetting/main.asp Heavy Petting]", ''Nerve'', March 2001.</ref> Singer stated that "mutually satisfying activities" of a sexual nature may sometimes occur between humans and animals and that writer Otto Soyka would condone such activities. Singer states that Dekkers believes that zoophilia should remain illegal if it involves what he sees as "cruelty", but otherwise is no cause for shock or horror. Singer believes that although sex between species is not normal or natural,<ref>In one decidedly non-academic interview, Singer said that he is "not in favor" of having sex with animals, and that having sex with other people is "more fun." (''The Colbert Report'', Comedy Central, December 11, 2006.)</ref> it does not constitute a transgression of our status as human beings, because human beings are animals or, more specifically, we are great apes.<ref name="heavy"/> Religious groups, animal rights groups, and others (such as the Christian Vegetarian Association{{Fact|date=February 2007}}) have condemned this view, while the animal rights organization PETA has supported them.<ref>Sarah Boxer, "[http://www.nytimes.com/2001/06/09/arts/09TANK.html?ex=1152504000&en=f35bfd2b6dbe11f7&ei=5070 Yes, but Did Anyone Ask the Animals' Opinion?]", ''The New York Times'', June 9, 2001.</ref>

====Immigration====
Singer holds that affluent nations have a duty to increase their refugee intake greatly. He suggests that such nations begin a yearly doubling of refugee quotas until immigration has reached a level where it is clear that further immigration will, on the whole, do more harm than good.

====The natural environment====
As the natural world is not sentient, Singer claims it has no intrinsic value. However, he says that the value to present and future sentient beings of maintaining the environment is so high that people and their governments should make drastic changes to their way of life to ensure the world's preservation.

====Evolutionary biology and liberal politics====
In ''A Darwinian Left'',<ref>''A Darwinian Left: Politics, Evolution, and Cooperation'', New Haven : Yale University Press, 2000, ISBN 0-300-08323-8.</ref> Singer outlines a plan for the political left to adapt to the lessons of Darwinism and evolutionary biology.  He says that evolutionary psychology suggests that humans naturally tend to be self-interested, and that leftists can't ignore scientific fact simply because it's unpleasant or inconvenient for achieving their political goals.  He further argues that the evidence that selfish tendencies are natural must not be taken as evidence that selfishness is right.  He concludes that game theory (the mathematical study of strategy) and experiments in psychology offer hope that self-interested people will make short-term sacrifices for the good of others, if society provides the right conditions. Essentially Singer claims that although humans possess selfish, competitive tendencies naturally, they have a substantial capacity for cooperation that has also been selected for by evolution. It is the job of the Left, he says, to create those conditions which foster cooperation amongst members of society.

=== Criticism ===
Singer's positions have been attacked by many different groups concerned with what they see as an attack upon human dignity, from advocates for disabled people to right-to-life supporters. He is also criticized by Roman Catholics and other Christians who think that Singer is immoral. 

Critics argue that Singer is in no position to judge the quality of life of disabled people. In Germany, his position has been compared to the Nazi practice of murdering "unworthy life", and his lectures have been repeatedly disrupted. Some claim that Singer's utilitarian ideas lead to eugenics. Nazi-hunter Simon Wiesenthal wrote to organizers of a Swedish book fair to which Singer was invited that "A professor of morals ... who justifies the right to kill handicapped newborns ... is in my opinion unacceptable for representation at your level."<ref>Don Felder, "[http://www.jewishworldreview.com/cols/feder102898.asp Professor Death will fit right in at Princeton], ''Jewish World Review'', October 28, 1998.</ref> Marc Maurer, President of the National Federation of the Blind, the leading organization for blind people in the United States, strongly criticized Singer's appointment to the Princeton Faculty in a banquet speech at the organization's national convention in July 2001, claiming that Singer's support for euthanizing disabled babies could lead to disabled older children and adults being valued less as well.<ref>http://www.nfb.org/Images/nfb/Publications/convent/banque01.htm</ref> Singer's conclusions in controversial areas such as abortion, infanticide and euthanasia may help explain why his works have attracted particular attention.

Some commentators expressed their disapproval at the publication of Singer's review essay in which he discusses bestiality as a logical conclusion to some of the arguments he has made with respect to the relationship of humans to animals.<ref>"[http://opinionjournal.com/editorial/feature.html?id=85000772 Animal Crackers]", ''The Wall Street Journal'', March 30, 2001.</ref>

Proponents of other ethical systems like deontology or virtue ethics have found in Singer's work ammunition against utilitarianism and its consequentialism (that is, its assumption that the morality of an act is to be evaluated according to its consequences). They claim that his conclusions show that utilitarianism may lead to eugenics, infanticide, or even justification of torture{{Fact|date=February 2007}} in certain circumstances.

Singer has replied that many people judge him based on secondhand summaries and short quotations taken out of context, not his books or articles.  For example, when people hear that Singer thinks that a dog has the same moral importance as a newborn baby, they might interpret the statement as dehumanising, because of the low value traditionally placed on the interests of animals.  However, although Singer does not regard the newborn child as deserving the same degree of consideration as an adult, he regards animals as deserving a much higher degree of consideration than they have traditionally been given.<ref>"[T]he aim of my argument is to elevate the status of animals rather than to lower the status of any humans" (''Practical Ethics'', p. 77).</ref>

Singer experienced the complexities of some of these questions in his own life. Singer's mother had Alzheimer's disease, which rendered her, in Singer's system, a "nonperson".  He did not have her euthanised, saying, "I think this has made me see how the issues of someone with these kinds of problems are really very difficult".<ref>Quoted in Michael Specter, "[http://www.michaelspecter.com/ny/1999/1999_09_06_philosopher.html The Dangerous Philosopher]", ''The New Yorker'', September 6, 1999.</ref> In an interview with Ronald Bailey published in December 2000 he explained that he is not the only person who is involved in making decisions about his mother (he has a sister). He did say that if he were solely responsible, his mother might not be alive today.<ref>Ronald Bailey, "[http://www.reason.com/0012/rb.the.shtml The Pursuit of Happiness]", ''Reason (magazine)'', December 2000.</ref> (Singer's mother died shortly thereafter.) This incident has led to accusations of hypocrisy. However,  Singer has never argued that a non-person who is not suffering ''has'' to be euthanised — only that it could be ''morally acceptable'' to do so.