Are We Born Knowing Anything? 我們生下來就知道什麼嗎？

🔊The first great argument for inborn knowledge is a demonstration. In Plato’s Meno, Socrates calls over a household slave, a boy who has never been taught geometry, draws a square in the sand, and asks him how long the side of a square twice as large would be. The boy answers confidently and wrongly, twice. Socrates then draws a few more lines and goes on asking questions, and the boy arrives at the correct answer, which is a hard one. Socrates insists that he told the boy nothing. “Without any one teaching him he will recover his knowledge for himself, if he is only asked questions.”

支持「天生知識」的第一個重要論證，是一場示範。在柏拉圖的《美諾篇》裡，蘇格拉底叫來一個家奴，一個從沒學過幾何的少年；他在沙地上畫了一個正方形，問少年：面積兩倍大的正方形，邊長是多少？少年很有把握地答錯了，而且錯了兩次。蘇格拉底接著又畫了幾條線，繼續提問；少年得出了正確答案，而那是個不容易的答案。蘇格拉底堅持，他什麼也沒有告訴少年。「沒有任何人教他，只要有人問他問題，他就會自己把知識找回來。」

🔊Plato’s explanation is that the soul existed before birth and learned everything then, so that “all enquiry and all learning is but recollection.” Few people have accepted the explanation. The demonstration is harder to dismiss. The boy did not learn the theorem by measuring squares, and once he sees it he sees that it must be so. Truths of that kind, known independently of experience, are called a priori, and they are the rationalist’s best evidence.

柏拉圖的解釋是：靈魂在出生之前就存在，並且在那時學會了一切，所以「一切探究、一切學習，都不過是回憶」。很少有人接受這個解釋。但那場示範比較難打發。少年並不是靠測量正方形學到這條定理的；而且他一旦看出來，就看出它「非如此不可」。這一類不依賴經驗而被知道的真理，稱為先驗的（a priori），是理性主義者最好的證據。

🔊The classic statement of the other side is John Locke’s, in An Essay Concerning Human Understanding (1690). “Let us then suppose the mind to be, as we say, white paper, void of all characters, without any ideas:—How comes it to be furnished?” His answer is one word: “from EXPERIENCE.” Experience has two channels. Sensation gives us ideas of yellow, hot, hard, and sweet. Reflection, the mind’s notice of its own operations, gives us ideas of thinking, doubting, and willing. Every other idea, however abstract, is built by combining and comparing these.

另一邊的經典陳述出自洛克的《人類理解論》（1690）。「那麼讓我們假設，心靈就像我們所說的那樣，是一張白紙，上面沒有任何記號，沒有任何觀念：它是怎麼被填滿的？」他的回答只有一個詞：「來自經驗。」經驗有兩個管道。感覺給我們黃、熱、硬、甜的觀念。反省，也就是心靈對自己運作的察覺，給我們思考、懷疑、意願的觀念。其他一切觀念，不管多抽象，都是把這些拿來組合、比較而造出來的。

🔊Locke had an argument as well as a picture. If any principles were stamped on the mind at birth, he said, everyone would be aware of them, and children plainly are not aware of the laws of logic. He also had a motive. Claims of innate truth had been used to put favored doctrines beyond question, and a mind that begins blank has to be given reasons.

洛克除了有一幅圖像，也有論證。他說，如果有任何原則在出生時就印在心靈上，那麼每個人都會察覺到它們；而小孩顯然並沒有察覺到邏輯定律。他也有動機。「天生真理」的說法，曾經被用來讓受偏愛的教條不容質疑；而一個從空白開始的心靈，別人必須給它理由。

🔊Leibniz read Locke’s Essay and wrote a book-length reply. He granted that nothing is in the intellect which was not first in the senses, and added three words: except the intellect itself. Locke had taken “innate” to mean “consciously present from birth,” which is easy to refute. The serious claim is that the mind has built-in tendencies. It is less like blank paper, Leibniz said, than like a block of marble with veins in it. The sculptor’s blows are needed to bring the figure out, and the veins make it easier to carve one figure than another. Experience is the occasion of our knowledge of necessary truths. It cannot be the source of their necessity, since no number of observed cases shows that a thing must be so.

萊布尼茲讀了洛克的《人類理解論》，寫了一整本書來回應。他承認「凡在理智中的，無不先在感官中」，然後加了幾個字：理智本身除外。洛克把「天生」理解成「從出生起就有意識地在場」，那很容易駁倒。嚴肅的主張是：心靈有內建的傾向。萊布尼茲說，與其說它像白紙，不如說它像一塊帶有紋路的大理石。要把雕像顯現出來，需要雕刻家的敲擊；而紋路使得雕出某個形象比雕出另一個容易。經驗是我們認識必然真理的機緣；它不可能是那些真理之必然性的來源，因為觀察到再多個案，也無法顯示一件事「非如此不可」。

🔊In China the same question was asked about morality. Mencius, in the fourth century BCE, held that the beginnings of goodness are part of our original equipment. “What people are able to do without having learned it is their innate ability; what they know without having to reflect is their innate knowledge (良知). There are no young children who do not know to love their parents.” Humaneness and rightness, he says elsewhere, “are not welded onto us from outside; we have them from the start.” He did not think that this made anyone good automatically. The beginnings are sprouts, and a sprout that is neglected dies. His opponent Xunzi argued that goodness is the product of deliberate effort and ritual training imposed on a nature that would otherwise run to conflict. Leibniz’s marble and Locke’s paper had been set against each other, on moral ground, two thousand years before either man was born.

在中國，同一個問題是針對道德問的。西元前四世紀的孟子主張，善的端倪是我們原初配備的一部分。「人之所不學而能者，其良能也；所不慮而知者，其良知也。孩提之童，無不知愛其親者。」他在別處說，仁義禮智「非由外鑠我也，我固有之也」。他並不認為這樣就讓任何人自動成為好人。那些端倪是芽，而芽被忽略就會死。他的對手荀子則論證說，善是刻意努力與禮的訓練的產物，是加在一個本來會走向爭奪的本性之上的。萊布尼茲的大理石與洛克的白紙，早在這兩個人出生的兩千年前，就已經在道德的領域裡對峙過了。

🔊A century after Locke, Immanuel Kant proposed terms of peace. “Though all our knowledge begins with experience,” he wrote, “it by no means follows that all arises out of experience.” The senses supply the material. The mind supplies the form in which any material must be arranged in order to be experienced at all: it places things in space and time and connects them as cause and effect. We are not born knowing any facts, on this view. We are born with the framework that makes facts available to us. Whether Kant identified the right framework is disputed. That some framework is needed is now close to common ground.

洛克之後一個世紀，康德提出了議和的條件。他寫道：「雖然我們的一切知識都始於經驗，卻絕不能因此說它全都出於經驗。」感官供應材料。心靈供應的是形式：任何材料要成為經驗，都必須被安排進這個形式裡；心靈把事物放在空間與時間之中，並且把它們連結成因與果。照這個看法，我們並不是生來就知道任何事實；我們生來就帶著讓事實得以向我們呈現的那個框架。康德認定的框架對不對，還有爭議。但「需要某種框架」，現在已經接近共識。

🔊Three lines of research have changed the debate. Infants only a few months old look longer at events that break the rules of solid objects, which suggests that they expect objects to persist and not to pass through one another. Children acquire grammar from a small and messy sample of speech, a fact Noam Chomsky called the poverty of the stimulus and took as proof of an inborn language faculty. And a question that the Irish scientist William Molyneux put to Locke in 1688 has been tested. Would a man born blind, who knew a cube and a sphere by touch, recognize them by sight alone if he were suddenly able to see? Locke said no. In 2011 researchers in India examined children just after surgery for congenital blindness. They could not match what they saw to what they felt, and they learned to do it within days.

有三條研究路線改變了這場辯論。才幾個月大的嬰兒，對違反固體規則的事件注視得比較久；這顯示他們預期物體會持續存在，而且不會彼此穿透。孩子從少量而雜亂的語言樣本就習得了文法；喬姆斯基把這個事實稱為「刺激的貧乏」，並且當作天生語言機能的證明。還有，愛爾蘭科學家莫利紐茲在 1688 年向洛克提出的一個問題，已經被檢驗了。一個生來失明、靠觸覺認得立方體與球體的人，如果突然看得見，單憑視覺認得出它們嗎？洛克說不能。2011 年，研究者在印度檢查了剛做完先天性失明手術的孩子。他們沒辦法把看到的跟摸到的配對起來；而他們在幾天之內就學會了。

🔊That result is a fair picture of where things stand. The newly sighted children had no ready-made knowledge linking sight to touch, as Locke predicted. They acquired it far faster than blank paper could, as Leibniz would have predicted. Neither side has been proved simply right. What has faded is the old either-or.

這個結果，相當公允地呈現了目前的局面。剛復明的孩子並沒有現成的、把視覺連到觸覺的知識，如洛克所預言。他們習得這種知識的速度，遠比白紙做得到的快，如萊布尼茲會預言的。沒有哪一邊被證明是單純地對。淡出的是舊日那個「非此即彼」。

🔊The question was never only academic. If the mind is white paper, education is everything, and differences among people are differences in what has been written on them. Locke drew that conclusion, and it has been a great engine of reform. If the mind has veins, a teacher’s task is to find them and work with them, which is what Socrates did in the sand. Each view has its danger. The first tempts us to think that children can be made into anything. The second tempts us to read our expectations into their nature. Mencius’s image may be the wisest of the three, since a sprout has a nature of its own and still has to be tended. He warns against the farmer who, impatient with his slow crop, went out and pulled on the shoots to help them grow.

這個問題從來不只是學術的。如果心靈是白紙，教育就是一切，人與人的差別就是寫在他們身上的東西的差別。洛克得出了這個結論，而它一直是改革的強大引擎。如果心靈有紋路，老師的任務就是找出紋路、順著它們工作；蘇格拉底在沙地上做的正是這件事。兩種看法各有危險。第一種誘使我們以為孩子可以被塑造成任何樣子。第二種誘使我們把自己的期待讀進他們的本性裡。孟子的意象也許是三者當中最有智慧的，因為芽有它自己的本性，卻仍然需要照料。他警告我們別學那個農夫：嫌莊稼長得慢，就跑去把苗一棵棵往上拔。