科學能否解釋人類意識 — 臭豆腐的疑惑

2019/5/7《立場新聞》

臭豆腐的化學成份

我很喜歡吃臭豆腐。以前香港有不少街邊舖或流動小販賣臭豆腐,逛街的時候未見臭豆腐先聞其香。可惜近年這股令人心曠神怡的氣味在市區已幾近絕跡。當然,臭豆腐不是人人能夠接受。據研究指出,臭豆腐的獨特氣味來自起碼數十種揮發性化合物,濃度較高的包括 [1] 

吲哚 (indole)

二甲基三硫醚 (dimethyl trisulfide)

二甲基二硫 (dimethyl disulfide)

二甲基四硫醚 (dimethyl tetrasulfide)

2,3,5-三硫雜己烷 (methyl methylthiomethyl disulfide)

苯酚 (phenol)

假使你從未品嚐過臭豆腐,你能否單憑以上的清單推斷出臭豆腐的氣味?當然,如果你懂化學,做實驗時嗅過這些化合物,你可能因此猜想到臭豆腐的氣味。不過,這是因為你的主觀經驗已經告訴你這些化合物是什麼氣味。如果你只是知道它們的份子結構和化學性質,但你有生以來從未接觸過這些化學成份,或任何帶有臭味的東西,那又如何?相信有很多人會認為,如果未曾經歷過近似的主觀經驗,那麼無論你的化學和生理知識如何豐富,你都永遠不能真正明白臭豆腐那一股獨特的濃烈氣味。

這個例子引伸出一個有趣而且重要的哲學問題。食物的色香味所帶來的主觀經驗,是人類心理意識的一部份,,但這些主觀經驗,能否完全得到客觀科學的解釋?如果不能,這又是否代表我們的意識永遠屬於科學領域以外的東西?

物理主義和知識論證

有些人可能覺得,這沒有什麼奇怪,因為意識是靈魂的一部份,靈魂不能透過科學方法解釋,所以意識也不可以。可是,我們又有什麼證據支持靈魂存在呢?大腦受到創傷可以影響認知能力,改變性情,令我們失去意識;科學家現在更可以透過腦部掃描,知道我們思考和做夢的一些比較簡單的內容,甚至預測我們某些行為和決定。如果心理現象不存在於大腦,而大腦的功能只是傳遞資訊給靈魂或者接收訊息,上述的現象應如何解釋 [2] 

到底靈魂或者其它靈界的事物是否存在,並非本文的焦點。不過,很多科學家和哲學家相信,雖然科學現在未能夠完全解釋人類的思想和意識等心理現象,這只是時間的問題。很多人類需要思考才可以做到的事情,人工智能可以通過電腦運算做得更快更好。我們也知道,人類的腦細胞網絡,也正正能夠作出複雜的運算;因此,人類的各種心理現象,有可能是由腦細胞的活動構成。腦細胞由化學物質組成,而這些化學物質,又是建基於更根本的粒子和能量等物理現象。換句話說,我們的心靈,以至整個大千世界,歸根究底都可能只是物理現象。這個立場通常稱為「物理主義 (physicalism) 」。

不過,臭豆腐的例子帶出一個問題:客觀的科學怎能容納主觀意識嗎?如果不能,這豈不是證明物理主義是錯的?分析哲學裡面的心靈哲學有一個有趣的「知識論證 (knowledge argument) 」,正正是提出這一個挑戰。這個論證來自澳洲哲學家傑克遜 (Frank Jackson) 的一個思想實驗 [3] ,我在這裡把論證修改了,應用在臭豆腐這個例子上。假設有一個女孩子嘉嘉不幸地患有先天性嗅覺缺失症 (congenital anosmia) ,出生以來便沒有嗅覺,嗅不到任何的氣味。不過,嘉嘉因此立志要成為一個研究大腦的科學家。嘉嘉冰雪聰明,記憶力強,很快便掌握了所有關於大腦神經系統以及有關的生理、化學和物理知識。天才橫溢的嘉嘉更因為卓越的研究而得到諾貝爾物理學獎、化學獎和醫學獎,比居禮夫人更厲害。我們假設嘉嘉對一切科學知識均瞭如指掌,無所不知。任何人吃臭豆腐時大腦的狀況,之後一系列的化學和生理反應以及行為,均在她的預測之內。

嘉嘉雖然擁有超乎常人的知識,但她從來沒有任何嗅覺的主觀經驗。問題是,她的科學知識是否足以令她明白臭豆腐的氣味呢?她會不會知道臭豆腐濃香撲鼻時那一種感覺是怎樣的呢?假設嘉嘉的嗅覺缺失症原來只是鼻子的神經線有毛病,一個小手術便可以解決問題,用不著打開腦袋 [4] 。試想想,手術後嘉嘉恢復了嗅覺,我們第一時間送上一磚臭豆腐,你認為嘉嘉會如何反應?相信很多人會同意,嘉嘉會發現一些她之前不知道的東西。嘉嘉可能會說:「哇!我之前雖然已經知道臭豆腐的化學成份和所有關於嗅覺以及大腦的科學知識,但到今天我才真正明白臭豆腐的氣味原來是這樣美妙的!太好味了!快多拿一碟來給我吃! 」

如果我們同意嘉嘉手術後才真正知道臭豆腐的味道,獲得新的知識,這便代表她以前的知識並不是所有關於嗅覺的知識。由於我們假設了嘉嘉一早已經掌握了所有相關的物理事實,所以她的新知識便肯定不是關於物理的事實。這似乎證明,我們的嗅覺意識其實涉及了一些物理知識以外的事實。換句話說,這個世界有些事實是關於科學不能解釋的非物理現象。因此,物理主義是錯的。

兩種知識

以上的知識論證,引起了很大的爭議。很多支持心物二元論的學者對論證表示贊同。他們認為物質與心靈是兩種截然不同的東西,兩者可以獨立存在,而科學只能解釋物質世界的運作。當然,也有很多哲學家和科學家反對這個知識論證。有趣的是,當初提出這個論證的哲學家傑克遜,現在卻不再接受自己的論證!然而,問題到底出在哪裏,到現在仍然眾說紛紜。

有一個講法認為,知識論證把兩種不同的知識混淆了 [5] 。知識可以分為資訊知識 (factual knowledge) 和技能知識 (ability) 兩大類。資訊知識是指對事實的認知,例如我們都知道 1+1=2 、鐵是一種金屬、月亮比地球小等等。這些資訊知識的內容都是一些事實,但技能知識卻不一樣;擁有技能並非純粹明白一些事實,而是懂得如何作出某些行為。例如一個曉游泳的成年人固然掌握了某些有關游泳的資訊,比如知道游泳時不應在水底呼吸,但知道這個事實,卻不代表做得到。初學者固然知道不應在水中呼吸,但下水之後卻可能心慌意亂,不自覺地把口張開而飲了一肚子水。所以習泳不能單在課堂聽講座,必須下水實習才行。

那麼這兩種知識與上述的知識論證又有何關係?簡單來說,支持物理主義的人可以這樣回答:這個世界所有的資訊知識都是關乎物理的知識,而嘉嘉在手術前也確實擁有所有關於臭豆腐的資訊知識。嘉嘉手術後第一次嗅到臭豆腐的香味,她也得到新的知識,但這其實只是新的技能而不是新資訊。套用之前的例子,一個科學家可能掌握了所有游泳的資訊,但依然不懂游泳。這個科學家欠缺的是技能而不是資訊,而我們也不可以因此認為游泳是一件超乎物理的現象。

這個回應可以稱為「技能論」。技能論是否正確,關鍵在於嘉嘉得到的新知識是否包括一些新的事實。贊同技能論的哲學家相信,嘉嘉現在終於明白臭豆腐的氣味,只是因為新的主觀經驗令她從此有能力辨認到臭豆腐的氣味,以及她可以想像和回憶這種氣味。這些新的技能並非一些事實,所以不能駁倒物理主義。

結語

有關知識論證的爭議,當然未曾因此完結。我自己也不接受知識論證,但亦不同意技能論的分析。技能論正確的地方,是指出了問題的關鍵在於釐清不同類型的知識,但我認為嘉嘉接觸臭豆腐後得到的新知識,並非純粹是一種技能,而是確實包括了一些資訊。這一類型的資訊告訴我們不同的主觀經驗是什麼感覺。

不過,要掌握這種資訊,我們必須運用一些感官概念,例如以「這一種臭味」來表達這一刻的感覺。這些概念透過主觀感覺來界定,與大部份的科學概念不一樣。科學知識運用的概念,通常是以一套理論來定義。科學概念雖然和感官概念有分別,但最重要的是,不同的概念可以是關於同一個現象,正如「我」和「這篇文章的作者」是指同一個人,卻表達了不同的概念。如果我失去了記憶,我依然知道我是我,但卻可能忘記了我是這篇文章的作者。所以,我們不能排除一個可能性,就是嘉嘉雖然手術後得到新的資訊知識,但這可能只是運用非科學性的感官概念來理解物理世界的事實,也就是說知識論證依然不能證明物理主義是錯的。

當然,這個回應是否真的合理,要仔細地分析和評估。此外,知識論證不能證明物理主義是錯,也不代表物理主義是對的。有興趣的讀者如果想進一步思考這個哲學問題,可以參考《史丹福哲學百科全書》的一篇相關文章 “Qualia: The Knowledge Argument” ,這篇文章有一定的難度,但很多哲學問題就是這樣:問題本身可能很容易理解,但要妥當地解答卻非常複雜和困難 [6] 。不過,這個世界本來就是複雜而微妙的。如果哲學能夠幫助我們認識這個世界,我們又怎能認為哲學理論一定要簡單易明呢?

註:

  1. Yuping Liu, Zhiwei Miao, Wei Guan and Baoguo Sun (2012). Analysis of Organic Volatile Flavor Compounds in Fermented Stinky Tofu Using SPME with Different Fiber Coatings. Molecules, 17, 3708- 3722.
  2. 有很多人認為瀕死經驗是證明靈魂存在的最佳證據。關於這方面的討論可以參考筆者這篇文章
  3. 見 Frank Jackson (1982). Epiphenomenal qualia. Philosophical Quarterly, 32, 127-136。 Jackson 原文的論證是關於一個在黑白世界生活、從來沒看過紅色的科學家。
  4. 當然,先天性嗅覺缺失症實際上並不是這樣簡單。
  5. David Lewis (1990). What experience teaches. 收錄在 William G. Lycan (ed.), Mind and Cognition. Blackwell.
  6. 比如「上帝是否存在」,「什麼是真理」,「道德是否客觀」等問題便是。
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Physician-assisted suicide

Physician-assisted suicide should be allowed in Hong Kong, out of compassion and respect for human dignity

Hon-lam Li and Y. F. Lau

7 Mar, 2019 in the SCMP

In 2017, an elderly Hong Kong man described by neighbours as a caring husband strangled his sick wife to end her suffering. Similar tragedies have taken place not just in Hong Kong but all over the world. Life is valuable, but should those who are terminally ill and in unbearable pain be made to prolong their life and excruciating suffering?

We believe that physician-assisted suicide should be legalised in Hong Kong. Autonomy is an important value. We ought to be able to choose our career, religion and lifestyle – and when the day comes, a peaceful and dignified death. We should respect a patient’s autonomous decision to end their life when faced with suffering that robs them of their dignity. However, to avoid abuse of medically assisted suicide, stringent conditions must be set.

First, the patient should be terminally ill. Second, there should be unbearable suffering, resulting in deterioration in quality of life. Third, it must be clear that death is not against the patient’s interests. Finally, the patient must be mentally competent and have persistently, desperately wanted to die because of their objective condition. Only then does the patient have the right to request physician-assisted suicide.

It is sometimes said that only God has the right to take life, and that medically assisted suicide is wrong. But we ought to remember that God is compassionate as well. Even the Catholic Church, which considers a fetus a human being, allows abortion in two cases: when the embryo is in the Fallopian tube, and when the mother has uterine cancer. Moreover, in a pluralist, secular society like Hong Kong, non-believers are not bound to any religious doctrine. In any case, the sanctity of life does not mean that it is always impermissible to take a human life. The law allows the use of deadly force in some cases of self-defence.

In assisted dying, the doctor helps the patient, who takes an active role in ending their life. For example, the doctor might prescribe a lethal dose of medication, and the patient can decide when and where to take it. One popular argument against medically assisted suicide is the slippery slope argument: if patients have the right to assisted dying, why not go further and allow doctors to kill dying patients who are too weak or paralysed to take their own lives?
What about patients who are not dying, but who still have to face years of intolerable physical or emotional pain? What if crippling paralysis causes patients to become dependent on others? Finally, why not extend assisted suicide to anyone who thinks life is suffering and who is determined to die, like a 17-year-old suffering unrequited love?

The slippery slope argument is a bad one. It assumes that because there is a continuum of suffering, the law cannot draw a line between cases where physician-assisted suicide is permissible and cases where it is not. But consider this analogy: just because there is no sharp line between safe and unsafe driving speeds does not mean we should impose just one speed limit for all roads. Instead of enforcing a blanket ban on physician-assisted dying, we should look at medical and policy factors in detail to identify a range of cases where the practice is permissible.

Some people worry that terminally ill patients, especially those from poor families, will be under pressure to opt for physician-assisted suicide. We should not assume beforehand that this will happen, just as people should not assume that the availability of medically assisted dying would cause hospitals to practise it before all palliative measures are taken. Certainly, this has not happened in the Netherlands or the state of Oregon, where the effects of assisted suicide have been studied.

On the contrary, after assisted dying became legal in Oregon, physicians have become more aware of patients’ need for palliative care, and patients have tended to receive better palliative care. But we agree that it is important for patients to know they have the right to reject assisted suicide. Hospitals and family members should also be prohibited from exerting pressure on patients.
According to the World Medical Association’s International Code of Medical Ethics, a physician shall “respect the rights and preferences of patients”, and act “with compassion and respect for human dignity”. The medical profession should uphold a patient’s interests – their well-being, autonomy and dignity – as its overriding priority.

Although no physician is under any obligation to help a patient die, the medical profession should not forbid its members from assisting suicide. It is time for Hong Kong to introduce the practice and put in place a set of regulations that exemplify compassion as well as respect for human dignity and autonomy.


Hon-lam Li is a professor in the Department of Philosophy, and deputy director of the Centre for Bioethics at the Chinese University of Hong Kong. Joe Y. F. Lau is an associate professor of philosophy at the University of Hong Kong. Joseph C.W. Chan, a professor in the Department of Politics and Public Administration, HKU, also contributed to this article

如何翻譯「critical thinking」?

劉彥方
香港大學哲學系
2015年5月28日

根據明報 2015年5月17日報導 [註1],葉劉淑儀於商台節目中批評香港教育局把「critical thinking」譯作「批判思考」。她認為這是錯誤的,容易令年輕人以為思考就是為了批判社會,使他們「先天與建制對立」。一個星期後,嶺大校長鄭國漢在培僑中學畢業禮致辭時,也提出類似的講法,並認為「critical thinking」的正確翻譯應該是「慎思明辨」。[註2]

葉劉淑儀不滿意「critical thinking」的翻譯,並非近期的事。早在 2007 年她已經有這樣的看法 [註3],2008年亦曾經在立法會要求政府把「critical thinking」的官方翻譯改為「明辨性思考」或「分辨性思考」[註4]。2014年12月,她再重提要求,並在立法會文件中引述相信是我在港大《思方網》的觀點,指出批判思考並非要我們刻意不停找別人錯處。[註5,6]

建制人士要為「critical thinking」改名,當然背後可能有政治動機。朗天便曾經在明報撰文 [註7],認為這只是「語言偽術」,目的是要打壓年輕人的獨立思考,製造「河蟹」氣氛。不過,我覺得改譯名的觀點並非全然沒有道理。而且不滿意「批判思考」這個翻譯的,大有人在。如果沒有弄錯,龍應台在2008年一場演講中也曾提議以「思辨能力」代替「批判思考」。

擱開政治動機不談,這個討論當中有幾個意見和論據值得留意。首先,葉劉淑儀在立法會 CB(2)222/08-09(01) 號文件說 critical thinking 最早是美國學者 Edward Glaser 於1941年提出的,鄭國漢也好像認同。不過這個顯然是錯了。其實 critical thinking 更早期的主要提倡者為美國哲學和教育學家杜威 (Dewey),即是胡適的老師。(Dewey之前有沒有我就不知道了。) 杜威 1910年的著作「How We Think」提倡「reflective thought」,很多人等同為「critical thinking」。但杜威在書中其實也有用過「critical thinking」一詞:

“The essence of critical thinking is suspended judgment; and the essence of this suspense is inquiry to determine the nature of the problem before proceeding to attempts at its solution.” (74頁)

以葉劉淑儀和鄭國漢倡議的「慎思明辨」來粗略形容 Dewey 和其他如 Glaser, Robert Ennis 等後來的學者對 critical thinking 的看法,我覺得問題不大,但這是否代表「critical thinking」不應譯作「批判思考」,而應該改為「思辨」或「明辨思考」呢?

有些支持「批判思考」譯法的人,會以歐陸哲學的批判傳統作為依據。朗天便以德國哲學家康德的《純粹理性批判》等三大巨著,以及其後歐陸哲學發展出來的批判理論 (critical theory) 為例子,指出「critical 」確實有批判社會及文化現象的意思。所以他覺得「critical thinking」用上「批判」一詞是恰當的。

不過,這個論據假設了「critical thinking」也是來自同一個思潮。這個我不太同意。教育哲學中有一套理論稱為「critical pedagogy」,確是源於批判理論,著眼點是反省和批判教育體制,理解意識型態和霸權對教育的操控,從而作出反抗而得到解放。「Critical pedagogy」翻譯為「批判教學論」,相信很少人會有異議。 但「critical thinking」和「critical pedagogy」並不一樣。杜威 1910年的「reflective thought」和「critical thinking」,大意是指審慎嚴謹的思考,當時批判理論尚未成形,而後來研究「critical thinking」的很多著名學者(例如Robert Ennis),也不是以批判理論或批判教學論的角度來界定這個概念的。他們的用法,與「critical analysis」裡面的「critical」較接近,和批評沒有必然的關係。當然,我認為 critical thinking 不單是可以,也是絕對應該用來批判建制,但這並不代表批判理論所指的批判是 critical thinking 的核心理念。

我自己對「critical thinking」應該如何翻譯,沒有強烈的意見。不過,「批判思考」由來已久,也在兩岸三地通行。這個翻譯可能不完美,但作為一個專用術語,大部份人現在都知道是指 critical thinking。教育局2014年回覆葉劉淑儀時說會以後採用「明辨(批判)性思考能力」作為「critical thinking」 的中譯,我覺得反而是多此一舉。

葉劉淑儀等人認為有些人會把「批判思考」誤解為批評別人。但他們好像沒有提供任何證據說明這個誤解到底有幾普遍。我自己覺得很多執於偏激批評的人,是性情或價值上出了問題,而非對「批判思考」有誤解。 而就算有,這個誤解稍加解釋便可以消除,不一定要修改既有的翻譯。況且,如眾人所言,「critical 」在英文起碼有兩個意思,所以「critical thinking」其實也有機會引致相同的誤解。而如果把中文「批判」二字拆開來看,「批」和「判」可以用於「批註」、「眉批」、「論批」、「判別」等詞語。這些詞語都帶有分析和評論的意思,不一定涉及負面的批評。

無論如何,即使「批判思考」使人聯想起批判,這也沒有什麼大不了。這個世代,荒謬恐怖的事情和混亂的思考多的是。思考方法在社會的一個主要功能,便是要指出這些不合理的現象。定義上「批判思考」當然不等同批判,但思考方法在實際運用上很難避免一定程度的批判。社會欠缺批判精神,何以進步?葉劉淑儀以為年輕人習慣批判社會是「先天與建制對立」,其實反映了她以為批判便是負面對立的誤解。葉劉淑儀在美國留學,照道理應該明白在西方的學術傳統中,批評不一定是負面的行為。學者最怕的便是沒有人批評自己的理論。著名的學者退休,最光榮的事情莫過於行內的學術巨頭和學生聚首一堂,討論和批評自己的論述,共同拓展知識的領域。而就算不講學術傳統,我不知道葉劉淑儀作為一個母親,有沒有曾經對女兒講過類似「我罵你是為你好」這樣的說話。市民對建制的批評,可以是沿於對社會的逼切關心和焦慮。建制派先天擁有強大的權力和資源,不應該把批評者看成敵人,而是應該虛心聆聽。然而,這恐怕只是空想。當批判思考的批判對象是既得利益和千絲萬縷的裙帶關係,批判者自然變成了對立的敵人,引來無數有形無形的打壓。教育局如何翻譯「critical thinking」都好,批判的思考和精神,絕對不可以放棄。

轉載 : 《立場新聞》 《評台》

The evolution of overconfidence : Nature : Nature Publishing Group

The evolution of overconfidence

Dominic D. P. Johnson & James H. Fowler

Nature 477, 317–320 (15 September 2011) doi:10.1038/nature10384

Confidence is an essential ingredient of success in a wide range of domains ranging from job performance and mental health to sports, business and combat1, 2, 3, 4. Some authors have suggested that not just confidence but overconfidence—believing you are better than you are in reality—is advantageous because it serves to increase ambition, morale, resolve, persistence or the credibility of bluffing, generating a self-fulfilling prophecy in which exaggerated confidence actually increases the probability of success3, 4, 5, 6, 7, 8. However, overconfidence also leads to faulty assessments, unrealistic expectations and hazardous decisions, so it remains a puzzle how such a false belief could evolve or remain stable in a population of competing strategies that include accurate, unbiased beliefs. Here we present an evolutionary model showing that, counterintuitively, overconfidence maximizes individual fitness and populations tend to become overconfident, as long as benefits from contested resources are sufficiently large compared with the cost of competition. In contrast, unbiased strategies are only stable under limited conditions. The fact that overconfident populations are evolutionarily stable in a wide range of environments may help to explain why overconfidence remains prevalent today, even if it contributes to hubris, market bubbles, financial collapses, policy failures, disasters and costly wars9, 10, 11, 12, 13.

via The evolution of overconfidence : Nature : Nature Publishing Group.

via The evolution of overconfidence : Nature : Nature Publishing Group.

The Pen Is Mightier Than the Keyboard

doi: 10.1177/0956797614524581

“Abstract

Taking notes on laptops rather than in longhand is increasingly common. Many researchers have suggested that laptop note taking is less effective than longhand note taking for learning. Prior studies have primarily focused on students’ capacity for multitasking and distraction when using laptops. The present research suggests that even when laptops are used solely to take notes, they may still be impairing learning because their use results in shallower processing. In three studies, we found that students who took notes on laptops performed worse on conceptual questions than students who took notes longhand. We show that whereas taking more notes can be beneficial, laptop note takers’ tendency to transcribe lectures verbatim rather than processing information and reframing it in their own words is detrimental to learning.”

via The Pen Is Mightier Than the Keyboard.

Self-deceived individuals deceive others better — ScienceDaily

Self-deceived individuals deceive others better — ScienceDaily.

via Self-deceived individuals deceive others better — ScienceDaily.

Over-confident people can fool others into believing they are more talented than they actually are, a study has found. These ‘self-deceived’ individuals could be more likely to get promotions and reach influential positions in banks and other organizations. And these people are more likely to overestimate other people’s abilities and take greater risks, possibly creating problems for their organizations.”