Critics say that his moral certainty is one of Singer's most significant flaws–that he is too demanding, too impersonal, and too dismissive of the way people actually relate to one another. In its rawest form, Singer's philosophy condemns people for caring more about their families than about strangers. "People do have special relationships with their families, their communities, and their countries,'' Alan Ryan, the warden of New College, Oxford, told me. Ryan has written extensively on John Stuart Mill and he taught for many years at Princeton. "This is the standard equipment of humanity, and most people, in all of human history, have seen nothing wrong with it. Singer is an interesting and important fellow, but I am afraid that human beings just aren't put together the way that he wishes they were." In Ryan's view, no moral philosophy that departs so fundamentally from such common sentiments could possibly make sense.
Other philosophers criticize Singer more for the logical consequences of his beliefs than for his refusal to acknowledge that emotion plays an essential role in the narrative of life. For example, if we could take an action today that would benefit many people in three thousand years, Singer would tell us to do it. It wouldn't matter that we would never see the benefits–or that the action might even cause us some harm. Yet predicting the long-term effects of something is like guessing how the winds passing over the Sahara this summer will affect the world's weather in fifty years. There will be an impact, but who could accurately assess it now? Often, acts that seem benevolent–such as providing aid to starving nations–can have unforeseen and disastrous results, causing warfare, corruption, and, ultimately, more starvation. Even Singer's laudable desire to reduce suffering in the present can be seen as a recipe for the ruin of the world economy. Colin McGinn, who is a professor of philosophy at Rutgers University, asks, "What if you took every penny you ever had and gave it to the poor of Africa, as he would have us do? What we would have is no economy, no ability to generate new wealth or help anybody.''
批判者たちは、シンガーの強い確信が、彼の最も重大な欠点の一つである、と言う。即ち、彼はあまりにも要求が高く、あまりにも個々人を無視しており、人々の他者との実際の関わり方をあまりにも否定し過ぎている、とのことである。最も荒削りな形態のシンガーの哲学は、他人よりも家族のことを気に掛けるとして人々を非難している。「実際のところ、人々は家族や共同体や国と特別な関係を持ちます」とオックスフォード・ニューカレッジ学長のアラン・ライアンは私に言った。ライアンはジョン・スチュアート・ミルに関する著作を数多く出しており、プリンストンで長らく教鞭を取っていた。「それは人間性の標準的な特性で、人類の歴史を通じて、ほとんどの人がそのことに問題があるとは考えてきませんでした。シンガーは興味深く重要な人物ですが、彼がそうあってほしいという形に人間というものは出来上がっていないのではないか、と私は思います。」 ライアンの見方では、そのような一般的な感情からこれほど根本的に乖離した倫理学は、まず意味を持つことはない。
他の哲学者は、人生において感情が重要な役割を演じることを認めない点よりも、彼の考え方の論理的帰結についてシンガーを批判する。例えば、今日取る行動によって3000年後に多くの人々が裨益するならば、シンガーは我々に対し、その行動を取るべきだ、と言うだろう。我々がその利益を目撃することは無い、もしくは、その行動で我々は幾らかの損害を蒙るかもしれない、というのは問題にならない。しかし、あることの長期的な影響を予測するのは、今夏にサハラに吹く風が50年後の世界の気候にどのような影響を与えるか、を推量するようなものである。影響はあるだろうが、誰が現時点でそれを正確に見積もることができようか? 飢餓に苦しむ国を援助するといった博愛的と思われる行動も、戦争や汚職、そして最終的にはさらなる飢餓をもたらす、という予期しない悲惨な結果を招くことがしばしばある。今日における苦痛を減らしたい、というシンガーの称賛に値する願いでさえ、世界経済の破滅への道筋となりかねない。ラトガーズ大学の哲学教授であるコリン・マッギンは、「彼が我々にそうさせたいと思っているように、人々が全財産をアフリカの貧しい人々に与えたらどうなるでしょうか? 経済は消滅し、新たな富を生み出したり誰かを助けたりする力は失われるでしょう」と言う。

Advocacy groups for the disabled say that one reason Singer writes them off is that he places too much trust in the prognoses of doctors. The medical profession does tend to rate the quality of life for children with disabilities less highly than their parents do. But parents almost always follow medical advice on what to do about an infant with suspected or known disabilities. If the doctors say that the kindest thing would be to let the child die, most parents acquiesce. If, on the other hand, they say, "Let's give the child a chance," that's what the parents will usually do.
Oddly, by arguing that disabled children should sometimes be killed, Singer seems, if anything, to be worrying too much about their pain. He is so devoted to the prevention of suffering–in a hen, a cow, or a human infant–that he dismisses the possibility that there might be more than that to many people's lives. "Most of us live through our own experiences," Rosemary Crossley told me. "So Peter assumes that people would be happy if they had the experiences that he had. For most of us, it is hard to live without reading, if you are a reader, or having sex, or jogging, or eating Chinese food. Whatever makes you happy, if you see people who cannot experience those things, you assume they cannot be happy. But that is not necessarily the case, and I don't think Peter has ever fully come to grips with that."
"Peter is a perfectly sincere man,'' McDonald told me. "But he thinks real life is not as important as intellectual life. So he can be very compelling when he talks about the intelligence and feelings of a pig. But he is somehow not as quick to understand what our problems and possibilities might be. He has all these big ideas, but he has never really gotten his hands dirty. Peter needs to get a little more involved in life if he wants to understand it."


*1:引用部の前段では、出生時の事故の後遺症により重度の知的障碍者と見做され病院に閉じ込められていたが、彼女に知性があることに気付いたクロスリーに助け出されて大学の学位を得るまでに至ったマクドナルドの経歴、および彼女とシンガーとの交流が描かれている。しかし、WikipediaのControversy欄にあるように、彼女が本当に知性と意思を疎通する能力を持っていたかについては今も議論が続いているらしい。クロスリーが開発した意思疎通の手段「facilitated communication」は実は疑似科学に過ぎず、介助者が障碍者の意見を代弁しているだけではないか、と主張する人もいるとの由。