Nature ought to have washed its hands of1) us by now, and if it hasnt yet, April 15s blasts in Boston should have persuaded it to. Its not just that were evil—though we are. We build bombs, we manufacture guns, we slaughter one another with an ugly lustiness that defies the powerful social impulses that are supposed to be coded into us.

The bigger problem for nature is that were also fools. If our genes have told us once, theyve told us a thousand times: stay out of harms way. When a madmans raging, when a bomb goes off, when a 110-story building is pancaking2) down and another one right next to it is about to do the same, run the hell away. Yes, yes, you hear a lot about fight or flight, but really, you want to live? Go for flight.

At the Boston Marathon on April 15 we saw it again. The bombs went off, the victims fell, the familiar footprint of flesh and blood and terror was stamped into the streets. And people did what they are hardwired3) to do, which is that they scattered—at first. And then an equally familiar gathering began. Police and servicemen swarmed the snow fences along the streets, pulling them down to allow medical personnel in. Doctors, paramedics4) and passersby knelt in the blood to administer aid to people they had never met before that moment and might never see after it. Perhaps there were more bombs that still could go off; perhaps the same madman who set off the first ones would show up with an assault weapon next. Never mind, the caregivers rushed in anyway.

There has always been this kind of opposing physics to good and evil. Evil begins from a point source—a cartridge5) of gunpowder, a nugget6) of uranium7), a knot of hate in a single dark mind—and then it blows outward. Good gathers from everywhere around the blast and then moves—foolishly, perilously, wonderfully—toward it.

“The police were trying to keep us back, but I told them I was a physician and they let me through,” Dr. Natalie Stevens, a participant in the race, told the New York Times. Stevens performed CPR8) on a woman whom she suspected was dead; she applied a tourniquet9) to the leg of a man who surely would have been had she not been here. And it would have made a lot more survival sense for her to have done nothing of the kind.

Ethicists, anthropologists and evolutionary biologists have tried for a long time to figure out why we do these things—why we put ourselves in mortal danger to save other people and, in so doing, defy our one great evolutionary imperative10), which is to stay alive ourselves. There are the reductionist11) explanations, of course. Its genetic mathematics, say the sociobiologists. Its not that youll help anyone at all, just the ones with whom you have some biological connection. Youre twice as likely to come to the aid of your parents, siblings and children, with whom you share 50% of your genes, than you are to help your grandparents, grandchildren, nieces and nephews, with whom you share 25%. You move on down this way in tidy arithmetical lockstep12) through your cousins and great half-aunts and great-great-great uncles, with their 12.5% and 6.25% and 3.13% relatedness and it all makes a perfect kind of crystalline13) sense, until you ask why then youd consider helping the bleeding stranger on the Boston streets, with whom you share no genes at all, and the sociobiologists start a lot of hand-waving about tribal relatedness and collective genetics and you pretty much stop listening.

Then there are the neurological explanations. Were sympathetic creatures, but not in the prettified way we usually use that word. Our brains are wired with mirror neurons14)—cells that make us mimic the behavior of the people around us, so that we laugh when they laugh and cry when they cry and yawn when they yawn. It feels like empathy, but its nothing of the kind. If you want to survive as a social creature, you have to behave like everyone else, and mirror neurons see to it that you do. Thats not empathy. Thats fitting in.

A similar mechanistic argument is made by scientists who scan the brain and actually see where goodness lives. Moral behavior is processed in the prefrontal15) cortex16) and the meso-limbic17) region. It follows a very mappable neuronal path that is no more complex than the one that allows you to throw a baseball or write your name, and thats no more lyrical either.

And yet, all these answers just smell wrong. You can deconstruct a painting by explaining the salts and sulfides18) and esters19) that make up its pigments; you can parse20) a symphony by measuring the frequency and wavelength of the final crashing chord, but youre missing the bigger picture.

Humans, instead, are guided by a sort of moral grammar—a primal ethical armature21) on which decency is built, just the way our language is built on syntax22) and tenses and conditional clauses. You know when a sentence is right and when it isnt even if you cant quite explain why, and you know the same thing about goodness too. Psychologist Michael Schulman of Columbia University likes to pose the thought experiment of the kindergarteners who are taught two rules: its not OK to eat in the classroom and its not OK to hit other children. Tell the kids that the teacher has lifted the no-eating rule and theyll happily eat. Tell them that the teacher has lifted the no-hitting rule and theyll uniformly balk23). “Theyll say, ‘Teacher shouldnt say that,” says Schulman. “That starts at a very young age.”

What starts young stays with us. Yes, were savage; yes, were brutal. It was a member of the home-team species, a homo sapiens24) like anyone else, who set the Boston bombs, and like it or not, that person is very close kin to you. But youre close kin to the first-responders too; youre close kin to the people who cried for the eight-year-old who died, not even knowing the childs gender or name, because an eight-year-old simply shouldnt die, and surely not the way this one did.

The very empathy that brings us to those tears need not be wasted on the person who committed the crime. Twelve years ago, when the rubble25) of the Sept. 11 attacks was still smoldering26), TIMEs Lance Morrow wrote, “Anyone who does not loathe the people who did these things, and the people who cheer them on, is too philosophical27) for decent company.” The same is true of the person or people responsible for the Boston slaughter.

But its equally true that the people who commit all of these crimes are, in many ways, the free radicals28) of our social organism—the atoms that go bouncing about, unbonded to anything, doing damage to whatever they touch. The bonds they lack are the ones the rest of us share—the ones that make us pull away the snow fences and kneel in the blood pools. “Morality,” says psychologist and ethicist Jonathan Haidt, “is a team sport.” Its far better to be part of that team than to be apart from it.

宇宙萬物的主宰如今應(yīng)該已不愿再管我們，如果還沒有，那么4月15日的波士頓爆炸案應(yīng)該足以說服它不再對人類抱有希望了。這不僅僅是因為人類邪惡——雖然人類的確邪惡。我們制造炸彈，生產(chǎn)槍支，相互屠殺，以丑陋的貪欲違抗本該像編碼那樣植入我們的強大的社會驅(qū)動。

但對萬物的主宰來說，更大的問題是我們?nèi)祟愅瑫r也是傻瓜。我們的基因曾上千遍地告訴我們：遇到災(zāi)禍躲著走。遇到瘋子發(fā)狂，炸彈爆炸，一幢110層的高樓轟然倒塌，旁邊另一幢也搖搖欲墜時，跑吧，拼命地跑。沒錯，沒錯，對于是留還是溜的問題，我們經(jīng)常爭論不休，但說到底，你想活命嗎？溜之大吉吧。

在4月15日的波士頓馬拉松比賽中，我們又看到了這一幕。炸彈爆炸了，受害者倒下了，街道上出現(xiàn)了熟悉的一幕——血肉橫飛，恐懼蔓延。人們出于本能做了該做的事：四處逃散。但這是在一開始。接著，同樣熟悉的另一幕出現(xiàn)了：人們開始聚集。警察和軍人紛紛涌向街道上的防雪柵欄邊，將柵欄拉倒，以方便醫(yī)護人員進入。醫(yī)生、護理人員和路人跪在血泊中，對那些他們此前從未見過、以后也可能永不再見的陌生人施以援手。也許還會有更多的炸彈爆炸，也許引爆這些炸彈的那個瘋子還會持攻擊性武器再次出現(xiàn)。但沒關(guān)系，救援人員依舊紛紛涌入。

正義與邪惡對立的現(xiàn)象自古有之。邪惡往往發(fā)自一個點，如一筒彈藥、一小塊鈾、一個陰暗心靈中埋藏的仇恨心結(jié)，然后向外爆發(fā)。正義則從爆炸點周圍的四面八方聚集過來，然后像傻瓜一樣不顧性命地沖向爆炸點，令人驚嘆。

“警察試圖將我們攔在外面，但我告訴他們我是醫(yī)生，他們就讓我進去了。”馬拉松參賽者納塔莉·史蒂文斯醫(yī)生對《紐約時報》說。史蒂文斯為一位她懷疑已經(jīng)死去的女性實施了心肺復(fù)蘇急救，還給一個男人的腿部綁上了止血帶——如果她不在場，這個男人肯定沒命了。從活命的角度來看，她不這樣做原本會更明智。

長期以來，倫理學(xué)家、人類學(xué)家和進化生物學(xué)家一直試圖解釋人們?yōu)槭裁匆@樣做，為什么我們會不顧生命危險去拯救他人，以此違抗進化論的一大法則——讓自己活著。當(dāng)然，還原主義者曾給出他們的解釋。社會生物學(xué)家就指出，這是基因運算的結(jié)果。人們并不會幫助所有人，只會幫助那些和他們有基因關(guān)系的人。比如，你和父母、兄弟姐妹、子女擁有50%的相同基因，而和祖父母、孫子孫女、侄子侄女只有25%的相同基因，因此你救助前者的可能性比你救助后者的可能性要高出一倍。以此類推，依照這種有規(guī)律的運算法則可以算到你堂表兄妹、半姨奶姑奶、曾曾舅老爺身上——你與他們分別有12.5%、6.25%、3.13%的親屬關(guān)系。至此這種解釋都看似無比清晰、完美，但你不禁要問，波士頓大街上那些流血的陌生人和你一點基因關(guān)系也沒有，你又為什么會考慮幫助他們呢？社會生物學(xué)家們又開始手舞足蹈地大談什么部落關(guān)系和集體遺傳學(xué)，你基本已經(jīng)聽不下去了。

此外還有神經(jīng)學(xué)上的解釋。人類是有同情心的物種，但這里所說的同情心并沒有我們通常所指的那種美化含義。我們的大腦中有一種叫鏡像神經(jīng)元的細胞，它使我們模仿周圍人的舉動。因此別人笑我們也笑，別人哭我們也哭，別人打哈欠我們也打哈欠。這聽起來像移情現(xiàn)象，但絕不是那么回事。如果你想作為一個社會動物而生存下去，你的舉止就必須像他人一樣，而鏡像神經(jīng)元的作用就是確保你這樣做。這不是移情，而是適應(yīng)環(huán)境。

有些科學(xué)家提出了另一種類似的機械論調(diào)，他們通過掃描人類大腦，確實發(fā)現(xiàn)了“善”存在的位置。前額葉皮質(zhì)和中腦邊緣區(qū)域就是處理道德行為的部位。道德行為遵循一種完全可以用圖表示的神經(jīng)元路徑，與那些可以使我們?nèi)影羟蚧驅(qū)懗鲎约好值穆窂揭粯?，它并無什么復(fù)雜之處，也沒有蘊藏什么豐富的感情。

然而，所有這些解釋都讓人感覺不對勁。你可以去解構(gòu)一幅油畫，說它的顏料中含有什么鹽、什么酯或者什么硫化物；你也可以去解析一首交響樂，測量它末尾那震撼人心的和弦有怎樣的頻率和波長。但這樣你就看不到更為宏觀的圖景了。

其實，人類是受某種道德規(guī)則支配的——那是一種原始的道德鎧甲，是正派、得體的基礎(chǔ)，正如我們的語言以句法、時態(tài)和條件從句為基礎(chǔ)一樣。你知道一個句子什么時候?qū)Γ裁磿r候錯，哪怕你無法給出明確的解釋。對于什么是善你也有同樣的感覺。哥倫比亞大學(xué)心理學(xué)家邁克爾·舒爾曼喜歡拿幼兒園兒童的一個思維實驗來說明問題。幼兒園教給孩子們兩條規(guī)則：不可以在教室里吃東西；不可以打其他孩子。如果告訴孩子們老師已經(jīng)取消了不許吃東西的規(guī)定，那么他們就會很開心地吃東西。但如果告訴他們老師已經(jīng)取消了不許打人的規(guī)定，他們卻會一致表現(xiàn)出畏縮?！八麄儠f：‘老師不應(yīng)該這樣說，”舒爾曼說，“這種觀念很小就有了。”

這種自小就有的觀念會一直伴隨我們。是的，我們很野蠻；是的，我們很殘忍。那個引爆波士頓炸彈的家伙和其他人一樣，都是那個以家庭為單位的物種的一員，是人類的一員。不管你喜不喜歡，那個人都和你十分相近。但和你相近的還有那些對爆炸案最早行動起來的人；和你相近的還有那些為那個死去的八歲孩童慟哭的人，他們甚至不知道孩子的性別和名字，他們哭只是因為一個八歲的孩子不應(yīng)該死去，更不應(yīng)該像這個孩子那樣死去。

對他人苦難的感同身受使我們流下眼淚，但這樣的淚水不需要浪費在罪犯身上。12年前，當(dāng)9·11恐怖襲擊的廢墟依然余燼未熄時，《時代周刊》的蘭斯·莫羅就曾經(jīng)寫道：“任何一個人，如果他不憎恨那些做出此事的人，或是為之喝彩，其心態(tài)之淡定都令有良知的人難以與之為伍?！边@話同樣適用于制造了波士頓殺戮事件的那個人，或者那些人。

但同時，從許多方面來說，那些犯下如此罪行的人是我們社會有機體中的自由基——那些游離不定的原子，不受任何約束，所到之處無不造成破壞。他們所缺乏的約束正是我們所共有的凝聚力——這種力量使我們將防雪柵欄推開，讓我們跪在血泊中救助他人?！暗赖率且环N團隊運動?！毙睦韺W(xué)家、倫理學(xué)家喬納森·海德特如是說。成為這個團隊的一員要遠遠好過脫離這個團隊。