『추상적인 善을 실현하려고 하지 말고, 구체적인 惡을 제거하기 위해 노력하라』

● 유복한 유대인 가정에서 출생, 젊은 시절 공산주의에 심취했으나 인간을 혁명의 도구로 여기는 데 실망하여 轉向
●『자유의 값은 영원한 不寢番』
●『열린 사회의 적, 그 뿌리는 마르크시즘과 파시즘』
●『합리적 인간이라면 마르크스에 대한 포퍼의 비판을 읽고 나서도 어떻게 마르크스주의자가 될 수 있을까』(英 옥스포드大 브라이언 매기 교수)
● 사회주의를「似而非 과학」,「似而非 神學」이라고 비판, 사회주의권內 反체제 세력에게 이론적 근거 제공, 사회주의의 몰락 지켜본 뒤 1994년 92세로 사망

全體主義의 희생자들을 위한 獻辭

「野人時代」라는 TV 드라마가 최고의 시청률을 기록한 적이 있다. 이 드라마의 주인공 金斗漢(김두한)은 日帝에 맞서는 當代의 영웅으로 묘사된다. 드라마 「野人時代」의 인기와 함께 건달에 대한 막연한 동경이 위험수위를 넘고 있다고 한다.

폭력조직을 담당했던 어떤 檢事(검사)는 폭력세계야말로 가장 의리 없고 야비한 곳 이라고 말한 적이 있다. 협객 金斗漢은 소설이나 드라마에서는 존재할 수 있어도 현실에서는 존재할 수 없다. 「野人時代」가 폭력을 미화하고 사실을 왜곡함으로써 시청자들, 특히 청소년들에게 좋지 못한 영향을 미치고 있다는 비판이 제기되는 것은 당연한 일이라고 할 것이다.

폭력에 대한 향수와 비뚤어진 민족주의가 드라마의 시청률에 영향을 미치는 정도라면 한때의 해프닝으로 넘어갈 수도 있을 것이다. 그러나 똑같은 심리상태가 全세계적인 전쟁과 학살을 가져온다면 어떻게 되겠는가.

바로 그런 일이 20세기에 일어났으며, 마르크스주의와 파시즘이 그 典型이라는 것을 밝힌 철학자가 있었다. 마르크스가「공산사회는 역사의 필연」이라는 소설을 썼을 때 수많은 사람들이 그것을 眞理로 받아들였다. 「아리안 민족의 위대한 전쟁」이라는 소설이 나치에 의해 쓰였을 때 많은 독일인들이 그것을 虛構(허구)로 생각하지 않았다. 이렇게 허구를 진리로 착각한 결과는 엄청난 재앙이었다.

20세기가 시작될 무렵에 태어나 끝날 무렵까지 살면서 體驗(체험)과 思惟(사유)를 통해 전체주의적 敎條(교조)가 얼마나 많은 사람들을 희생시켰는가를 고발한 사람, 그가 바로 칼 포퍼였다. 그는 다음과 같은 獻辭(헌사)를 올렸다.

『역사적 운명의 냉혹한 법칙을 믿는 파시스트와 코뮤니스트의 신념에 의해 희생된, 온갖 이념과 국가와 인종의 수많은 남녀들을 추모하면서 …』

칼 라이문트 포퍼(Karl Raimund Popper)는 1902년 7월28일 오스트리아의 빈(Vienna)에서 1男2女의 막내로 태어났다.

그의 아버지 지몬 지그문트 포퍼(Simon Sigmund Karl Popper)는 빈 대학에서 법학박사 학위를 받은 변호사로서 매우 학구적인 사람이었으며 사회개혁가로 활동했다. 포퍼의 아버지는 유대인이었지만 편협한 유대 민족주의를 비판하면서 개신교(루터교)로 개종했고, 유명한 법률회사의 首席 변호사로 일했다.

그의 집에는 큰 서재가 있었는데 1만 권이 넘는 藏書(장서)로 채워 있었으며, 주방을 제외하고는 집 안 어디에나 책이 있었다고 한다. 포퍼의 외가는 음악가 집안이었다. 포퍼의 가족은 교양 있고 부유했으며 다양한 사회지도층 인사들과 친분을 맺고 있었다. 유년 시절의 포퍼는 유복한 환경에서 책 속에 파묻혀서 성장했다.

1914년 포퍼의 열두 번째 생일잔치가 있던 바로 그날 제1차 세계대전이 일어났다. 1918년 3월 독일과 소련의 講和(강화)조약이 체결되었다. 강화조약이 체결될 때 트로츠키를 비롯한 러시아 공산주의자들은 非폭력 평화주의를 강조하는 一連의 연설을 통해 조약의 명분을 쌓았다. 포퍼는 그 연설문을 들으면서 그 속에 들어 있는 平和主義(평화주의)와 理想主義(이상주의)에 매료되었다.

1918년 11월 독일과 오스트리아의 항복으로 전쟁이 끝나면서 포퍼 가족의 행복도 날아가 버렸다. 극심한 인플레이션으로 인해 그들이 누리던 富는 한순간에 사라져 버렸다. 굶주린 시민들이 暴動을 일으키고, 때때로 銃擊戰(총격전)까지 벌이는 불안한 상황이 이어졌다. 경제적 곤궁과 사회적 혼란을 겪으면서 열여섯 살의 포퍼는 현실에 대한 반항심과 공산주의에 대한 기대감을 가지고 家出을 해버렸다.

그는 「사회주의 중등학생 연맹」의 열성적인 회원이 되었다. 공산주의의 가르침을 따라 육체노동자가 되기 위해 캐비닛 제조공장의 見習工(견습공)으로 일하기도 했고, 사회민주당 黨員이 되어 공산주의 활동에 동참했다.

한편으로는 생계를 위해 美國人 학생에게 수학과 물리학을 가르치며 돈을 벌기도 했다. 친구들과 함께 알프스 산맥을 누비는가 하면, 독서와 음악에 심취하기도 했다.

젊은 시절에 경험했던 이러한 방황과 자유는 그에게 山과 음악, 「열린 자세」에 대한 사랑을 심어 주었고 예민한 道德感을 남겨 주었다. 특히 도덕에 관한 청교도적 자세는 모든 자극제(stimulants)를 혐오하는 것으로 이어졌는데, 술에 취해서 마차 바퀴옆에 쓰러져 있는 사람을 본 이후 평생토록 술을 가까이 하지 않았을 정도였다.

인간을 혁명의 수단으로 여기는 공산주의에 실망

1919년 포퍼는 공산당 사무실에서 자원봉사자로 활동했는데, 여기서 공산주의의 實狀(실상)을 체험하게 된다. 공산당이 모스크바의 명령에 절대적으로 服從(복종)하면서 矛盾的(모순적)인 일을 서슴지 않는다는 사실을 알게 된 것이다.

특히 빈(Vienna) 경찰청 앞에서 발생했던 사건은 그에게 큰 충격을 주었다. 1919년 공산주의자들은 투옥된 동료들을 석방시키기 위해 경찰청 앞에서 示威(시위)를 벌였는데, 이때 경찰이 發砲(발포)하여 여섯 명의 젊은이가 목숨을 잃고 말았다. 포퍼는 당시의 사건을 이렇게 회고했다.

『나는 그 광경을 보았습니다. 그때 나도 그곳에 있었거든요. 공산당 지도자들은 그것이 혁명을 위해서 필요한 정도의 분노를 자극하는 데 도움이 된다고 보았습니다. … 그들은 벌어진 참사에 대해 반성하지 않았습니다. … 공산당은 다른 사람들이 위험을 무릅쓰도록 고무했고 결국 그들이 총에 맞도록 내버려 두었습니다』

이 사건을 계기로 포퍼는 공산주의에 대해 철저히 공부해 보기로 마음먹고 마르크스의 「자본론」을 숙독했다. 그 결과 오스트리아 공산당의 행동이 「천박한 마르크스주의」에 해당된다는 것을 깨달았다. 더 큰 문제는 공산당이 자신들의 행동을 革命을 위한다는 명분으로 正當化하고 있다는 점이었다.

공산주의에 실망하고 있던 포퍼는 아인슈타인(A. Einstein)의 一般相對性理論(일반상대성이론)을 접하고 흥미를 느꼈다. 그러나 막상 아인슈타인의 강의를 들었을 때 그는 현기증을 느낄 만큼 그것이 어렵다는 것을 깨달았다고 한다. 그 후 포퍼는 정신분석학자 아들러(A. Adler)를 도와 孤兒(고아)들을 위한 자선활동에 참여하기도 하였다. 이곳 저곳을 방황하던 포퍼는 이번에는 音樂家가 되기 위해 빈(Vienna) 음악대학에 등록하였다. 그곳에서 1년간 수업을 받으면서 작곡의 기초를 배우고 실제로 오르간 음악을 작곡하기도 했다.

1922년 포퍼는 방황을 마치고 빈 대학에 입학했다. 대학에 입학한 후 포퍼는 심리학에 관심을 가졌으나, 뷜러(K. Bu..ler)와 곰퍼츠(H. Gomperz) 두 교수를 만나면서 철학, 특히 과학철학에 관심을 갖게 되었다. 빈 대학에서 數學과 哲學, 物理學을 공부한 포퍼는 1928년 철학박사 학위를 취득했다.

포퍼의 가능성을 인정한 곰퍼츠 교수는 빈 學團(Logical Positivism of the Vienna Circle)의 회원이었던 크라프트(V. Kraft)에게 포퍼를 소개해 주었다. 빈 학단은 당시 철학계에서 한참 대두되고 있던 논리실증주의자들의 모임이었다. 포퍼는 빈 학단의 세미나에 참석하면서 카르납(R. Carnap), 파이글(H. Feigl), 슐릭(M. Schlick), 바이스만(R. Weismann) 등과 토론하면서 친교를 나누었다. 그러나 포퍼는 논리실증주의에 반대하는 입장을 취했기 때문에 빈 학단으로부터 「공식적인 반대자(Official Opposition)」라는 별명을 얻었다.

대학교를 졸업한 후 그는 中學校 敎師로서 학생들에게 수학과 물리학을 가르치는 한편, 철학 세미나에 참여하면서 철학자로서의 도약을 준비하고 있었다. 1934년 포퍼는 자신의 첫번째 저서인 「탐구의 논리」를 발간하게 되는데, 이 책을 통해 그는 학계의 주목을 받게 된다.

「우리 모두는 틀릴 수 있다」

영국의 經驗主義(경험주의) 哲學者 베이컨은 『우리가 순수한 마음으로 자연이라는 책을 대하면 결코 잘못 읽는 일이 없을 것』이라고 말했다. 觀察(관찰)과 經驗을 통해 참된 知識(지식)을 얻을 수 있다는 주장이다. 경험주의 철학에서는 구체적인 사례를 관찰하여 모아 놓은 다음 그것에 기초하여 보편적인 진술을 만드는 방법, 즉 歸納法(귀납법)을 과학적 방법으로 생각하였다.

빈 학단의 論理實證主義者들은 이러한 경험주의 전통에 입각해서 경험에 의해서 檢證(검증)될 수 있는 것만이 有意味(유의미)하고 科學的이라고 주장했다. 이들에 의하면 「영혼은 불멸한다」와 같은 形而上學的(형이상학적) 言明들은 검증될 수 없기 때문에 과학적일 수 없다.

그런데 과연 관찰을 통해서 발견한 사실이 정말로 과학적이라고 할 수 있을까? 例를 들어 보자. 하루가 지나면 다음날 아침 다시 해가 떠오른다는 것은 인류가 있어 온 이래 계속 관찰되었던 사실이다. 그래서 우리는 내일 아침에도 해가 뜰 것이라고 기대한다. 하지만 이것은 엄밀히 말해 심리적 기대이지, 논리적 귀결은 아니다. 미래의 언젠가 해가 뜨지 않는 날이 있는지 없는지를 지금 관찰할 수는 없기 때문이다.

포퍼는 논리실증주의자들이 형이상학과 윤리학을 非과학적인 것으로 몰아붙였지만 정작 그 자신도 非과학적이기는 마찬가지라고 비판하면서, 과학을 과학으로 만드는 것은 檢證이 아니라 「反證(반증) 가능성(Falsification)」이라고 주장한다.

과학은 檢證된 경험을 하나하나 쌓아 올리는 작업이 아니라 대담한 추측과 상상력의 所産(소산)이다. 이러한 상상과 통찰력을 과학적인 것으로 만드는 것은 바로 反證 가능성, 반박 가능성이다.

만약 어떤 과학이론이 경험에 의해서 반박된다면, 그 이론은 지금까지 지켜왔던 科學으로서의 자리를 내놓고 새롭고 더 나은 이론이 그 자리를 차지하게 된다. 만약 어떤 이론이 오랜 기간 동안 反證과 반박을 이겨낸다면 그 이론은 좋은 이론이라 할 수 있지만, 그것 역시 「잠정적인 진리」라는 데는 변함이 없다. 요컨대 과학을 과학으로 만드는 것은 反證 가능성이 열려 있느냐의 與否이며, 진리는 언제나 잠정적이라는 것이다.

포퍼의 이러한 科學觀은 토론과 비판을 허용하는 분위기를 요청한다. 우리 인간은 항상 틀릴 수 있는 가능성을 가진 불완전한 존재이다. 그렇기 때문에 누구도, 어떤 의견도 비판받아야 한다. 이렇게 인간의 有限함에 대한 자각적 인식, 즉 「우리 모두는 틀릴 수 있다」는 사실을 사회적, 정치적, 제도적으로 승인하는 사회가 바로 「열린 사회」이다. 이런 사회에서 인간은 비판과 토론과 민주적 의사결정을 통해 誤謬(오류)를 줄여 나갈 수 있는 것이다.

나치의 탄압을 피해 뉴질랜드로 망명

「탐구의 논리」는 학계의 다양한 분야로부터 好評을 받았다. 그 책은 당시 프린스턴 대학에 재직하고 있었던 아인슈타인에게 전달되었는데, 그는 포퍼에게 「당신의 책은 여러 가지 면에서 나를 기쁘게 하였습니다」라고 칭찬하는 편지를 보냈다. 아인슈타인은 포퍼가 귀납적 방법론을 비판하고 반증주의를 내세운 것이 과학철학에서 결정적인 위치를 차지하게 될 것이라고 평가했다.

런던경제대학에 在職하고 있던 하이에크(F. A. Hayek)도 포퍼의 책을 높이 평가했다. 그는 포퍼의 이론이 자신의 경험주의적 접근방법을 가다듬고, 實證(실증)경제학의 假定(가정)들을 비판하는 데 도움이 될 것이라고 생각하면서 영국에서 열리고 있었던 자신의 세미나에 포퍼를 演士로 초청했다.

논리실증주의자들은 포퍼의 책을 달가워하지 않았다. 특히 논리실증주의의 巨頭이자 케임브리지 대학의 교수였던 비트겐슈타인은 포퍼와 매우 불편한 관계가 되었다. 後日 포퍼가 런던경제대학의 강사가 되었을 때 비트겐슈타인의 세미나에 초청받은 일이 있었는데, 이때 비트겐슈타인은 포퍼에 대한 反感을 감추지 않아서 두 사람은 몸싸움을 벌이기 直前까지 이를 정도였다(비트겐슈타인과의 불편한 관계는 後日 포퍼가 케임브리지 대학의 교수가 되지 못하고 런던경제대학의 교수로 남게 되는 한 원인이 되었다).

學界에서는 포퍼의 이름이 聲價(성가)를 올리고 있었지만, 정작 故鄕 오스트리아에서는 중학교 선생 자리도 지키기 어려워지고 있었다. 1930년대에 접어들면서 파시스트들이 점점 더 우세하게 되면서, 反유대주의 감정이 점점 더 노골적으로 표출되고 있었던 것이다.

포퍼는 개신교도였기 때문에 스스로를 유대인이라고 생각하지 않았지만, 그건 포퍼의 생각일 뿐이었다. 그의 부모가 모두 유대인이었기 때문에 포퍼는 당연히 유대인으로 취급받았고, 그로 인해 여러가지 不利益을 겪었다.

영국에서 순회강연을 마치고 돌아왔을 때 포퍼는 오스트리아가 곧 히틀러에 의해 장악될 것이라고 예감했다. 때마침 그에게 반가운 소식이 찾아왔다. 뉴질랜드의 캔터베리 대학에서 강사職 제안이 들어온 것이다. 1937년 3월 뉴질랜드로 떠난 포퍼는 그 후 9년 동안 그곳에서 생활하게 된다.

「열린 사회와 그 敵들」

포퍼는 뉴질랜드 캔터베리 대학에서 유일한 철학자였기 때문에 논리학, 철학史, 윤리학과 정치학 등 철학 분야에서 개설된 모든 강의를 도맡아서 해야 했다.

제2차 세계대전이 벌어지자 포퍼는 오스트리아 출신이라는 이유로 황당한 일을 겪기도 했다. 포퍼를 매우 못마땅하게 생각하던 서덜랜드(I. Sutherland)라는 교수는 포퍼가 영국에 충성하지 않는다는 소문을 퍼뜨리더니, 급기야 경찰에 포퍼를 申告해 버린 것이다. 이 사건은 학장의 보증으로 수습되었다. 하지만 유대인이라는 이유로 오스트리아에서 불이익을 받았던 포퍼로서는 뉴질랜드에서 오스트리아人이라는 이유로 불이익을 받게 되자 매우 불쾌한 감정을 느끼지 않을 수 없었다.

뿐만 아니라 포퍼는 다른 동료 교수에 비해 월등히 많은 강의를 하고 있었지만, 급료에 있어서 심한 차별을 받았다. 포퍼가 뉴질랜드에서 지낸 9년 동안 동료들의 월급은 최소한 네 차례 이상 오른 반면, 그의 월급은 단 한 번도 인상되지 않았다. 포퍼는 이런 처우에 대해 불만을 가졌으며, 그를 지지하는 몇몇 교수들은 대학 당국에 항의했다. 그럴 때마다 대학 당국의 답변은 이런 식이었다.

『지금 이 자리가 포퍼에게 가장 좋은 곳이라는 것을 우리는 알고 있습니다. 그가 다른 곳으로 가고 싶다면 우리는 붙잡지 않을 것입니다』

오스트리아 亡命客이 전쟁 중에 갈 곳이 어디 있겠느냐는 것이었다.

포퍼가 뉴질랜드에 온 지 얼마 후 히틀러는 오스트리아를 합병했다. 곧이어 1939년 제2차 세계대전이 발발했다. 포퍼는 오스트리아 출신의 학자로서 세계를 비극으로 몰아넣은 파시즘에 대해서, 그리고 마르크스주의에 대해서 무엇인가를 해야 한다는 의무감을 느끼지 않을 수 없었다.

1938년 히틀러가 오스트리아를 합병한 직후부터 포퍼는 책을 하나 저술해야겠다고 마음먹었는데, 그로부터 6년여의 시간이 지난 뒤에 결실을 볼 수 있었다. 여건이 좋았다면 그렇게 오랜 시간이 걸리지 않을 수도 있었겠지만 그가 처한 조건은 너무나 劣惡(열악)했다. 언어 문제를 극복해야 했고, 종이도 스스로 구해야 했으며, 자신이 손으로 원고를 쓰고 아내가 타이핑을 해야만 했다.

「역사주의의 빈곤」(1944)과 「열린 사회와 그 敵들」(1945)이라는 위대한 저작은 이렇게 해서 세상에 나오게 되었다. 이를 통해 포퍼는 마르크스주의와 파시즘을 통렬하게 비판하면서, 바람직한 사회의 모델로서 「열린 사회」를 主唱(주창)하였다.

마르크스주의는 似而非 과학이자, 似而非 神學

마르크스주의의 중심을 이루는 주장은 자기의 이론이 「科學的」이라는 것이다. 마르크스는 인간 사회의 발전이 科學的 法則(법칙)에 따라 이루진다고 하면서, 그가 하고 있는 작업은 바로 그 과학적 법칙을 발견하는 것이라고 확신했다. 그는 「자본론」에서 자본주의의 「法則과 傾向性(경향성)」은 피할 수 없는 결과를 향하여 「必然的으로 움직인다고 하면서, 先進 산업국가는 後進 산업국가에 대하여 그 자신의 미래의 이미지를 보여 줄 뿐이라고 주장했다.

포퍼의 과학이론에 따르면 어떤 이론이 과학적 진리이기 위해서는 反證에 견딜 수 있어야 한다. 마르크스의 이론이 확실한 과학적 진리라면 무수한 반증을 견뎌낼 수 있어야 한다. 마르크스주의가 반증에 견뎌 냈을까? 결코 그렇지 않다. 오히려 마르크스주의만큼 反證에 脆弱(취약)한 理論이 없을 정도이다.

마르크스의 이론에 따르면, 成熟(성숙)한 자본주의 사회만이 공산주의로 移行(이행)하며 모든 사회는 먼저 자본주의 단계를 거쳐야 한다. 그러나 체코슬로바키아를 제외 하고는 공산화된 모든 나라가 산업사회를 거치지 않은 상태의 나라였다.

또 마르크스 이론은 혁명이 산업 프롤레타리아(無産階級)에 기반을 두게 마련이라고 했다. 그러나 毛澤東, 胡志明, 피델 카스트로는 그것을 명백히 배격하여 農民에 기초하여 혁명을 일으켰다. 그리고 그의 이론에 의하면 산업 프롤레타리아는 필연적으로 점점 더 빈곤해지고 그 수가 漸增하게 되어 있으며, 그에 따라 이들의 계급의식이 高揚(고양)되고 혁명의 열기가 높아진다고 했다. 그러나 마르크스 이후 모든 산업국가에서 프롤레타리아는 점점 더 부유해졌으며 그 수가 줄어들었고 계급의식이 감소되었으며 혁명의 열기가 식어갔다.

뿐만 아니라 공산주의는 노동자 대중에 의해서만 초래된다고 했지만 실제로 공산당이 권력을 장악한 곳에서는 군대, 그것도 주로 外國 군대의 힘에 의해 국민에게 공산주의를 덮어씌웠다. 그리고 자본주의의 생산수단이 점점 더 극소수의 손에 장악되어 간다고 했지만, 시간이 흐름에 따라 주식회사가 확대되어서 생산수단의 소유가 점점 더 널리 분산되고 전문경영인까지 나타나게 되었다. 이렇듯 마르크스주의의 무수한 言明들이 反證에 여지없이 허물어지고 말았다. 따라서 마르크스 이론은 과학의 자리에서 내려와서 무덤 속으로 들어가는 것이 마땅하다.

그런데 마르크스를 추종하는 이들은 결코 그것을 포기하려 하지 않았다. 그들은 反證을 교묘하게 피할 수 있도록 그 이론을 再구성하고자 했다.

이에 대해 포퍼는 『반박되고 거짓으로 판명되어도 補助假說(보조가설) 등을 동원하여 그 反證에서 면제되려고 하는 것이야말로 似而非(사이비) 과학의 특징』이라고 했다. 그리고 마르크스주의에는 종교적 신앙과 같은 反證 불가능한 확신이 있으므로 그것은 분명히 似而非 神學임에 틀림없다고 하였다(예를 들면 東歐 사회주의가 붕괴하는 것을 보고 난 뒤 舊소련을 비롯한 현실 사회주의가 실상은 국가독점자본주의였다는 궤변을 늘어 놓는 미국의 左派 이론가 이매뉴얼 월러스틴 등이 似而非 과학자의 전형이라고 할 수 있을 것이다).

『역사주의와 유토피아주의의 신성치 못한 동맹』

마르크스주의자들이 자신의 이론에 대해 종교적 신앙과 같은 것을 갖는 이유는 그 안에 내재해 있는 歷史主義(역사주의) 때문이다. 역사주의란 「역사란 불가피한 방향과 불변하는 궁극적 목적을 가지고 있으며, 그것은 운명적인 것으로 변경될 수도 없고 변경되어서도 안 된다는 歷史觀」이다.

마르크스는 역사주의에 입각해서 자신이 역사의 필연적 방향을 파악했다고 주장했다. 이것은 마치 물리학에서 日蝕(일식)과 月蝕(월식)이 일어나는 날짜와 시간을 정확하게 예측할 수 있는 것과 마찬가지로 마르크스주의가 자본주의의 운명을 정확하게 예측할 수 있다는 의미이다. 따라서 마르크스의 추종자들은 그 이론으로부터 자연과학에서 얻을 수 있는 확신과 같은 종류의 확신, 더 나가서는 종교와 같은 신념을 갖게 되는 것이다.

그렇다면 과연 역사의 미래를 과학적으로 인식하는 것이 가능한 일일까?

포퍼는 명백히 불가능하다고 말한다. 자연현상에는 「法則」이 존재하지만 사회현상에는 법칙이 아니라 「趨勢(추세)」가 존재할 뿐이다. 「법칙」이 존재하는 경우 일정한 因果(인과)관계가 성립되기 때문에 과학적 예측이 가능하다. 그러나 「추세」가 존재하는 경우에는 전제 조건이 변함에 따라 전혀 다른 결과가 나올 수 있기 때문에 과학적 예측이 불가능하다. 포퍼는 『역사주의자들이 「법칙」과 「추세」를 구분하지 못하는 치명적인 실수를 범했다』고 하면서 다음과 같이 말한다.

『역사주의자들은 자기의 마음에 드는 추세를 굳게 믿고 있으며, 이 추세를 사라지게 할 조건이 나타나리라고는 꿈에도 생각하지 않는다. 역사주의자들은 자기가 살고 있는 세계에서 일어날 변화를 상상하지 못하는 사람들을 끊임없이 나무란다. 그러나 정작 상상력이 빈곤한 사람은 역사주의자 자신이다. 그들은 변화의 조건이 변화한다는 것을 생각하지 못하기 때문이다』

역사주의가 과학적으로 似而非라는 사실보다 더 심각한 문제가 있다. 이것이 필연적으로 유토피아적 社會工學으로 연결되어서 독재와 폭력을 초래한다는 점이다. 포퍼는 이러한 현상을 『역사주의와 유토피아주의의 신성치 못한 동맹』이라고 불렀다.

역사주의자들은 자신이 미래의 역사를 알고 있다고 생각하고 그것을 앞당기기 위한 실천적 프로그램을 추진하게 된다. 이들은 필연적으로 실현될 미래에 관한 「理想的設計圖(설계도)」를 그려 놓고 그것에 따라서 「사회 전체」를 개혁하고자 한다.

그런데 미래의 역사를 실현하기 위한 사회계획은 탁월한 능력을 가진 사람이 수행해야만 한다. 따라서 독재자의 등장은 자연스럽고 정당한 것이며 대중은 그에게 복종할 의무를 갖는다. 지도자의 領導(영도)를 따라 미래를 실현하는 과정에서 장애물이 없을 수 없다. 특히 역사를 모르거나 또는 알고 있으면서도 방해하려는 의도를 가진 자들이 문제다. 이들을 어떻게 할 것인가? 평화적으로 설득할 수 없다는 것은 자명하다. 유일한 방법은 폭력적인 수단을 통해 消滅(소멸)시키는 것이다.

마르크스주의를 받아들인 나라들이 하나같이 一黨(個人) 獨裁로 치달으면서 피로 얼룩진 虐殺(학살)과 肅淸(숙청)을 일삼았던 이유가 바로 여기에 있다. 마르크스주의와 마찬가지로 역사주의에 입각하고 있었던 파시즘 역시 같은 이유에서 독재자가 등장하고 전쟁을 일으켰으며 人種淸掃(인종청소)를 자행했던 것이다.

「역사주의의 빈곤」과 「열린 사회와 그 敵들」이 영국에서 출판되면서 포퍼는 영국 철학계의 스타가 되었다. 당대의 철학자 러셀(B. Russell)은 포퍼의 책을 最上의 가치를 갖는 작품이라고 평가했다. 정치가들도 左派와 右派를 막론하고 그 책의 가치를 높이 평가했다. 1950년대에 이르면서 그 책은 사회주의圈 학자들에게까지 영향을 미쳐서 소련에서 地下출판(Samizdat)되기까지 했다.

하이에크, 포퍼를 런던경제대학으로 불러들이다

런던경제대학의 경제학 교수로 재직하고 있었던 하이에크는 「탐구의 논리」(1934)를 읽은 이후 포퍼와 절친한 사이가 되어 전쟁 중에도 꾸준히 연락을 주고 받았다. 하이에크도 「열린 사회와 그 敵들」을 읽고 깊은 감명을 받아 포퍼를 런던경제대학으로 불러들여야겠다고 마음먹었다. 마침 런던경제대학의 「논리학 및 과학방법론」 강사 자리가 비게 되었고 하이에크는 포퍼로 하여금 지원하도록 했다.

1945년 末 런던경제대학의 강사채용위원회가 열렸을 때 포퍼의 채용여부는 불투명했다. 하이에크나 러셀과 같은 지지자들은 그를 강하게 추천했지만 반대자들은 그에게 거부감을 느끼고 있었다.

그 이유는 포퍼가 플라톤과 헤겔을 「全體主義의 아버지」라는 이유로 강하게 비판했기 때문이었다. 포퍼는 헤겔에 대해 다음과 같은 毒舌을 퍼부었다.

『그의 글은 독창성이 없기로는 최상급이다. … 탁월한 점이 전혀 없는 그의 사상과 방법은 하나의 목적에 바쳐졌다. … 「열린 사회」에 대항하여 투쟁하는 것과 그의 고용주인 프러시아王에게 봉사하는 것이다』

우여곡절을 겪은 끝에 포퍼는 런던경제대학의 강사로 채용되어 1946년 1월 런던으로 왔다. 런던경제대학에서 그가 개설한 강의는 학생들로부터 선풍적인 인기를 끌었다.

런던경제대학의 강사가 된 지 얼마 지나지 않아서 다른 대학에서 포퍼를 정식 교수로 채용하겠다는 제안이 들어오기 시작했다. 먼저 오스트리아의 빈 대학으로부터 제안이 들어왔다. 포퍼는 이 제안을 단호하게 거절했다. 그의 가족은 나치로부터 피해를 입지 않았지만, 친척 중에는 16명이나 나치에 의해 희생되었고, 오스트리아에 여전히 反유대주의가 남아 있었기 때문이었다. 이어서 케임브리지대학에서 비트겐슈타인의 후임 교수를 채용한다는 소식이 들려왔고, 포퍼에게 지원해 보라는 제안이 들어왔다. 하지만 비트겐슈타인을 비롯해 몇몇 교수들이 포퍼의 공격적인 성격을 문제 삼았기 때문에 그는 지원하지 않았다. 그리고 이어서 뉴질랜드로부터 이전보다 더 좋은 조건으로 그를
채용하겠다는 제안이 들어왔다.

이처럼 포퍼의 聲價가 높아지자 런던경제대학에서는 1949년 포퍼를 정식 교수로 임용했다. 이후 그는 1969년 은퇴할 때까지 런던경제대학의 교수로 재직하게 된다.

「열린 사회」는 인간이 인간으로 살아남기 위한 유일한 길

포퍼는 마르크스주의와 파시즘, 그리고 그것의 始祖가 되는 플라톤과 헤겔을 묶어서 「열린 사회의 敵」으로 규정했다. 그렇다면 敵들로부터 마땅히 지켜야 할 「열린 사회」는 과연 어떤 사회를 말하는 것일까?

첫째, 「열린 사회」는 批判(비판)을 受容(수용)하는 사회이다. 이것은 포퍼의 科學觀으로부터 나오는 개념이다. 즉 反證 가능한 것만이 과학이라고 할 수 있는 것과 마찬가지로 자유로운 비판이 허용되는 사회만이 「열린 사회」이다.

이런 사회에서는 어떤 것도 독단적인 권리를 가질 수 없다. 사회규범도 인간이 만든 것으로서 비판의 대상이 되며 그러한 비판이 타당한 것으로 합의될 경우 언제라도 바뀔 수 있다. 정부의 정책도 마찬가지로 비판의 대상이 된다. 정부의 정책은 이성과 경험의 테스트를 받아야 하며, 그렇게 될 때 정책이 실패할 가능성이 그만큼 낮아진다. 비판을 허용하는 「열린 사회」는 서로 상충하는 의견이 자유롭게 표출되고 엇갈리는 목표들이 다양하게 추구될 수 있는 多元的인 사회이다.

둘째, 「열린 사회」는 個人主義 사회이다. 「열린 사회」에서 사회는 독립적이고 자유로운 개인들의 집합으로 파악한다.

사회를 구성하는 개인은 전체의 일부가 아니라 개체로서 자유와 권리를 갖는다. 개인은 독자적으로 판단을 내리고 결과에 책임을 진다. 내가 어려운 상황에 처하게 된 것은 어느 누구의 탓도 아니다. 부모의 잘못도 아니고 사회의 잘못도 아니다. 설사 그들의 잘못이라고 해도 그들이 내 인생에 대해 책임 질 수는 없다. 내 인생은 내가 살아가야 한다. 이러한 태도는 운명이 정해져 있지 않기 때문에 스스로 운명을 만들어 갈 수 있다는 믿음에서 나온다.

셋째, 「열린 사회」는 弱者(약자)를 보호하는 사회이다. 「열린 사회」에서 개인은 자신의 운명을 개척해 나가는 평등한 존재이다.

그런데 어떤 개인이 극단적인 빈곤에 처하게 되면 불가피하게 평등한 존재로서의 개인의 位相이 위축된다. 따라서 사회의 구성원은 굶어 죽는 것이나 경제적 파멸의 두려움으로 인해 불평등한 관계 속으로 빠져들어가지 않도록 보호받아야 한다. 이러한 역할을 하는 것이 바로 국가이다. 그런데 국가는 언제나 權力을 濫用할 가능성을 가지고 있기 때문에 「열린 사회」에서 국가는 「必要惡」으로 규정된다.

넷째, 「열린 사회」는 自由民主主義 사회이다. 국가는 권력을 남용할 가능성을 가지고 있기 때문에 被지배자(시민)는 지배자(정부)를 통제할 수 있는 권리를 가져야 한다.

이러한 권리는 지배자를 교체할 수 있는 권리를 포함하는데, 다만 그 과정에서 폭력이 사용되어서는 안 된다. 이것은 多數의 지배(이것은 多數決에 의한 폭력을 정당화한다) 로서의 민주주의가 아니라, 정부에 대한 자유로운 비판을 허용하고 평화적 방법을 통한 정권교체를 가능하게 하는 자유민주주의이다.

포퍼는 항상 틀릴 가능성을 가지고 있는 인간의 「有限性」을 보완해 주는 사회가 바로 「열린 사회」이며, 오직 「열린 사회」만이 인간의 誤謬(오류)를 최소한으로 줄여 줄 수 있다고 하면서 이렇게 말한다.

『우리는 禽獸(금수)로 돌아갈 수도 있다. 그러나 우리가 인간으로 살아남고자 한다 면 오직 하나의 길이 있을 뿐이다. 그 길은 「열린 사회」의 길이다』

『구체적인 惡을 제거하기 위해 노력하라』

그렇다면 「열린 사회」로 나가는 방법은 무엇일까?

물론 「열린 사회」의 敵들에 대한 경계를 늦추지 말아야 할 것이다. 자유의 값은 영원한 不寢番(불침번)이기 때문이다. 그렇다면 불침번만 잘 서면 「열린 사회」가 저절로 오는 것일까? 포퍼는 이 세상을 좀더 좋은 세계로 만들기 위한 의식적인 노력이 있어야 한다고 강조한다.

그런데 여기서 주의해야 할 것은 좋은 사회를 만들기 위한 노력은 「사회 전체」를 再구성하려는 노력이 아니라는 점이다. 포퍼는 그런 식의 노력을 유토피아적 사회공학이라고 부르면서, 그것이 필연적으로 폭력을 수반한다고 하였다.

그렇다면 「열린 사회」를 만들어 가기 위한 노력은 무엇일까? 포퍼는 유토피아적 사회공학에 대비하여 「漸進的 社會工學」을 제시한다.

점진적 사회공학의 핵심은『직접적인 수단을 이용하여 惡을 제거하라』는 것이다. 다시 말해 목적은 「惡의 제거」이고 수단은 「직접적인 방법」이다. 포퍼의 말을 직접 들어보자.

『추상적인 善을 실현하려고 하지 말고, 구체적인 惡을 제거하기 위해 노력하라. 정치적 수단을 사용하여 행복을 이룩하려고 하지 마라. 구체적인 비참함을 없애는 것을 목적으로 삼아야 한다. 좀더 구체적으로 말하면 직접적인 수단을 사용하여 가난을 없애려고 노력해야 한다』

포퍼가 理想的인 사회에 대한 청사진이 아니라 구체적인 社會惡의 제거를 사회공학의 목표로 삼아야 한다고 생각한 이유는 목표설정이 용이하기 때문이다. 이상적인 善에 대한 합의는 어렵지만, 구체적인 惡에 대한 합의는 쉽고 명백하다. 어떤 사회가 이상적인지에 대해서는 사람마다 생각이 다르기 때문에 모든 사람이 동의할 수 있는 이상적인 목표를 정하는 일은 거의 불가능하다. 설사 그런 목표를 정할 수 있다고 하더라도 사회는 대단히 복잡하기 때문에 그 목표를 달성할 수 있는 수단이 무엇인지를 찾는 일은 대단히 어렵다.

그리고 포퍼는 『정치적인 手段에 의해 인간을 幸福하게 하려고 해서는 안 된다』고 주장한다. 왜냐하면 「행복의 성취는 개인적인 노력에 달린 문제」이기 때문이다. 公共정책의 가장 긴급한 문제는 인간의 고통이며, 행복은 긴급한 문제가 아니다. 인간의 고통을 해소하려는 公共정책은 失業보험, 불경기에 대한 대책, 교육개혁 등과 같이 단일한 문제에 관한 것이기 때문에 실천방법이 복잡하지 않고, 만약 실패하더라도 재앙으로 연결되지는 않는다.

또한 포퍼는 惡을 제거하기 위해 「구체적인 방법」을 선택해야 한다고 주장한다. 이러한 주장이 의미하는 바는 『理想鄕(이상향)을 달성함으로써 간접적으로 惡을 제거하려고 해서는 안 된다』는 것이다. 지금의 가난, 실업, 질병 등과 같은 惡을 먼 장래의 유토피아 건설에 의해 간접적으로 제거하려고 하면 지금 당장 고통받는 사람들을 외면하게 되고, 미래의 꿈을 실현하기 위해 現 세대의 희생을 강요하게 된다. 가난한 사람을 구제하는 수단은 직접적인 방법(쌀을 주든지, 돈을 주든지)이지, 미래의 꿈이 아니라는 것이다.

이렇듯 포퍼가 제시하는 점진적 사회공학은 「사회 전체」를 개혁하려는 유토피아적 사회공학에 반대하면서, 계속적인 小규모의 조정과 再조정을 통해 인간의 고통을 줄여 나감으로써 좀더 나은 사회로 조금씩 전진해 나가는 방법이다.

사회주의권內 反체제 세력에게 이론적 근거 제공

포퍼의 사회철학은 공산주의에 대한 가장 강력한 무기였다. 「열린 사회와 그 敵들」이 세상에 나왔을 때 이미 파시즘은 무덤 속으로 들어가고 있었지만, 공산주의는 「역사적 필연」을 내세우며 冷戰의 한 軸을 이루고 있었다.

하지만 그의 철학 앞에서 공산주의는 속수무책이었다. 사회주의圈 지식인들조차 禁書(금서)로 지정된 포퍼의 책들을 비밀리에 출판하여 읽고 있었다. 「열린 사회와 그敵들」은 사회주의권內에서 형성된 反체제 세력의 중요한 이론적 근거가 되었다. 이런 점에서 옥스포드대학 교수 브라이언 매기의 다음과 같은 지적은 매우 타당한 것이라고 생각된다.

『합리적 인간이라면 마르크스에 대한 포퍼의 비판을 읽고 나서도 어떻게 마르크스 주의자가 될 수 있을까 하는 것을 나는 아무리 생각해 봐도 알 수가 없다』

영국 여왕 엘리자베스 2세는 1965년 포퍼에게 騎士(기사) 爵位(작위)를, 1982년에는 大英제국 명예훈위를 수여했다. 그리고 토크빌賞, 교토賞, 괴테 메달 등 많은 상을 수상했다. 그의 저서는 40여 개국 語로 번역되어 출판되었으며, 10여 개의 대학에서 그에 게 명예학위를 수여했다.

그의 晩年에는 독일의 바이츠체커 대통령, 슈미트 수상, 콜 수상, 일본 국왕, 달라이 라마, 체코의 하벨 대통령 등이 그를 방문하여 환담을 나누었다. 하지만 포퍼가 누린 가장 큰 영광은 그가 사이비 과학이라고 통렬하게 비판했던 사회주의가 무너지는 것을 지켜본 것이었다.

소련·東歐의 사회주의가 무너진 지 3년 후인 1994년 9월17일, 포퍼 는 영국 런던에서 편안하게 눈을 감았다.

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열린사회와그적들

칼 포퍼 | 이한구 | 민음사 |

책소개 전체주의 혐오…플라톤, 헤겔, 마르크스 비판『열린사회와 그 적들』은 전체주의 정치체제의 이념적 허구성과 비도덕성에 대한 치밀하고 통렬한 비판서이며, 동시에 열린사회로 인도하는 가장 확실한 실천철학적 안내서이다. 이 책이 처음 출간...

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추측과 논박(1 (과학적 지식의 성장)

칼 포퍼 | 이한구 | 민음사 |

책소개 '반증가능성'이란 개념으로 현대 과학철학사에 큰 획을 그은 칼 포퍼의 주저.『추측과 논박』은 포퍼가 자신의 사상의 근간이 되었던 주요 논문과 강연문 21편을 묶은 책이다. 이 글들은 과학 철학, 고대 철학, 칸트 철학과 자연과학, 변증법 등...

Life

Karl Raimund Popper was born on 28 July 1902 in Vienna, which at that time could make some claim to be the cultural epicentre of the western world. His parents, who were of Jewish origin, brought him up in an atmosphere which he was later to describe as 'decidedly bookish'.

His father was a lawyer by profession, but he also took a keen interest in the classics and in philosophy, and communicated to his son an interest in social and political issues which he was to never lose. His mother inculcated in him such a passion for music that for a time he seriously contemplated taking it up as a career, and indeed he initially chose the history of music as a second subject for his Ph.D examination. Subsequently, his love for music became one of the inspirational forces in the development of his thought, and manifested itself in his highly original interpretation of the relationship between dogmatic and critical thinking, in his account of the distinction between objectivity and subjectivity, and, most importantly, in the growth of his hostility towards all forms of historicism, including historicist ideas about the nature of the 'progressive' in music.

The young Karl attended the local Realgymnasium, where he was unhappy with the standards of the teaching, and, after an illness which kept him at home for a number of months, he left to attend the University of Vienna in 1918. However, he did not formally enrol at the University by taking the matriculation examination for another four years. 1919 was in many respects the most important formative year of his intellectual life. In that year he became heavily involved in left-wing politics, joined the Association of Socialist School Students, and became for a time a Marxist.

However, he was quickly disillusioned with the doctrinaire character of the latter, and soon abandoned it entirely. He also discovered the psychoanalytic theories of Freud and Adler (under whose aegis he engaged briefly in social work with deprived children), and listened entranced to a lecture which Einstein gave in Vienna on relativity theory. The dominance of the critical spirit in Einstein, and its total absence in Marx, Freud and Adler, struck Popper as being of fundamental importance: the latter, he came to think, couched their theories in terms which made them amenable only to confirmation, while Einstein's theory, crucially, had testable implications which, if false, would have falsified the theory itself.

Popper obtained a primary school teaching diploma in 1925, took a Ph.D. in philosophy in 1928, and qualified to teach mathematics and physics in secondary school in 1929. The dominant philosophical group in Vienna from its inception in 1928 was the Wiener Kreis, the circle of 'scientifically-minded' intellectuals who gathered around the figure of Moritz Schlick. This included Rudolf Carnap, Otto Neurath, Viktor Kraft, Hans Hahn, and Herbert Feigl. The principal objective of the members of the Circle was to unify the sciences, which carried with it, in their view, the need to eliminate metaphysics once and for all by showing that metaphysical propositions are meaningless.

Thus was born the movement in philosophy known as logical positivism, and its chief tool became the verification principle. Although he was friendly with some of the Circle's members - especially Feigl, who encouraged him to write his first book - and shared their esteem for science, Popper was heavily critical of the main tenets of logical positivism, especially of what he considered to be its misplaced focus on the theory of meaning in philosophy and upon verification in scientific methodology.

He articulated his own view of science, and his criticisms of the positivists, in his first work, published under the title Logik der Forschung in 1934. The book - which he was later to claim rang the death knell for logical positivism - attracted more attention than Popper had anticipated, and he was invited to lecture in England in 1935. He spent the next few years working productively on science and philosophy, but storm clouds were gathering - the growth of Nazism in Germany and Austria compelled him, like many other intellectuals who shared his Jewish origins, to leave his native country.

In 1937 Popper took up a position teaching philosophy at the University of Canterbury in New Zealand, where he was to remain for the duration of the Second World War. The annexation of Austria in 1938 became the catalyst which prompted him to refocus his writings on social and political philosophy. In 1946 he moved to England to teach at the London School of Economics, and became professor of logic and scientific method at the University of London in 1949. From this point on Popper's reputation and stature as a philosopher of science and social thinker grew enormously, and he continued to write prolifically - a number of his works, particularly The Logic of Scientific Discovery (1959), are now universally recognised as classics in the field. He was knighted in 1965, and retired from the University of London in 1969, though he remained active as a writer, broadcaster and lecturer until his death in 1994 (For more detail on Popper's life, cf. his Unended Quest).

Backdrop to his Thought

A number of biographical features may be identified as having a particular influence upon Popper's thought. In the first place, his teenage flirtation with Marxism left him thoroughly familiar with the Marxist view of economics, class-war, and history. Secondly, he was appalled by the failure of the democratic parties to stem the rising tide of fascism in his native Austria in the 1920s and 1930s, and the effective welcome extended to it by the Marxists.

The latter acted on the ideological grounds that it constituted what they believed to be a necessary dialectical step towards the implosion of capitalism and the ultimate revolutionary victory of communism. This was one factor which led to the much feared Anschluss, the annexation of Austria by the German Reich, the anticipation of which forced Popper into permanent exile from his native country. The Poverty of Historicism (1944) and The Open Society and Its Enemies (1945), his most impassioned and brilliant social works, are as a consequence a powerful defence of democratic liberalism as a social and political philosophy, and a devastating critique of the principal philosophical presuppositions underpinning all forms of totalitarianism.

Thirdly, as we have seen, Popper was profoundly impressed by the differences between the allegedly 'scientific' theories of Freud and Adler and the revolution effected by Einstein's theory of relativity in physics in the first two decades of this century. The main difference between them, as Popper saw it, was that while Einstein's theory was highly 'risky', in the sense that it was possible to deduce consequences from it which were, in the light of the then dominant Newtonian physics, highly improbable (e.g. that light is deflected towards solid bodies - confirmed by Eddington's experiments in 1919), and which would, if they turned out to be false, falsify the whole theory, nothing could, even in principle, falsify psychoanalytic theories.

These latter, Popper came to feel, have more in common with primitive myths than with genuine science. That is to say, he saw that what is apparently the chief source of strength of psychoanalysis, and the principal basis on which its claim to scientific status is grounded, viz. its capability to accommodate, and explain, every possible form of human behaviour, is in fact a critical weakness, for it entails that it is not, and could not be, genuinely predictive. Psychoanalytic theories by their nature are insufficiently precise to have negative implications, and so are immunised from experiential falsification.

The Marxist account of history too, Popper held, is not scientific, although it differs in certain crucial respects from psychoanalysis. For Marxism, Popper believed, had been initially scientific, in that Marx had postulated a theory which was genuinely predictive. However, when these predictions were not in fact borne out, the theory was saved from falsification by the addition of ad hoc hypotheses which made it compatible with the facts. By this means, Popper asserted, a theory which was initially genuinely scientific degenerated into pseudo-scientific dogma.

These factors combined to make Popper take falsifiability as his criterion for demarcating science from non-science: if a theory is incompatible with possible empirical observations it is scientific; conversely, a theory which is compatible with all such observations, either because, as in the case of Marxism, it has been modified solely to accommodate such observations, or because, as in the case of psychoanalytic theories, it is consistent with all possible observations, is unscientific.

For Popper, however, to assert that a theory is unscientific, is not necessarily to hold that it is unenlightening, still less that it is meaningless, for it sometimes happens that a theory which is unscientific (because it is unfalsifiable) at a given time may become falsifiable, and thus scientific, with the development of technology, or with the further articulation and refinement of the theory. Further, even purely mythogenic explanations have performed a valuable function in the past in expediting our understanding of the nature of reality.

The Problem of Demarcation

As Popper represents it, the central problem in the philosophy of science is that of demarcation, i.e. of distinguishing between science and what he terms 'non-science', under which heading he ranks, amongst others, logic, metaphysics, psychoanalysis, and Adler's individual psychology.

Popper is unusual amongst contemporary philosophers in that he accepts the validity of the Humean critique of induction, and indeed, goes beyond it in arguing that induction is never actually used by the scientist. However, he does not concede that this entails the scepticism which is associated with Hume, and argues that the Baconian/Newtonian insistence on the primacy of 'pure' observation, as the initial step in the formation of theories, is completely misguided: all observation is selective and theory-laden - there are no pure or theory-free observations. In this way he destabilises the traditional view that science can be distinguished from non-science on the basis of its inductive methodology; in contradistinction to this, Popper holds that there is no unique methodology specific to science.

Science, like virtually every other human, and indeed organic, activity, Popper believes, consists largely of problem-solving.
Popper, then, repudiates induction, and rejects the view that it is the characteristic method of scientific investigation and inference, and substitutes falsifiability in its place.

It is easy, he argues, to obtain evidence in favour of virtually any theory, and he consequently holds that such 'corroboration', as he terms it, should count scientifically only if it is the positive result of a genuinely 'risky' prediction, which might conceivably have been false. For Popper, a theory is scientific only if it is refutable by a conceivable event. Every genuine test of a scientific theory, then, is logically an attempt to refute or to falsify it, and one genuine counter-instance falsifies the whole theory.

In a critical sense, Popper's theory of demarcation is based upon his perception of the logical asymmetry which holds between verification and falsification: it is logically impossible to conclusively verify a universal proposition by reference to experience (as Hume saw clearly), but a single counter-instance conclusively falsifies the corresponding universal law. In a word, an exception, far from 'proving' a rule, conclusively refutes it.

Every genuine scientific theory then, in Popper's view, is prohibitive, in the sense that it forbids, by implication, particular events or occurrences. As such it can be tested and falsified, but never logically verified. Thus Popper stresses that it should not be inferred from the fact that a theory has withstood the most rigorous testing, for however long a period of time, that it has been verified; rather we should recognise that such a theory has received a high measure of corroboration. and may be provisionally retained as the best available theory until it is finally falsified (if indeed it is ever falsified), and/or is superseded by a better theory.

Popper has always drawn a clear distinction between the logic of falsifiability and its applied methodology. The logic of his theory is utterly simple: if a single ferrous metal is unaffected by a magnetic field it cannot be the case that all ferrous metals are affected by magnetic fields. Logically speaking, a scientific law is conclusively falsifiable although it is not conclusively verifiable. Methodologically, however, the situation is much more complex: no observation is free from the possibility of error - consequently we may question whether our experimental result was what it appeared to be.

Thus, while advocating falsifiability as the criterion of demarcation for science, Popper explicitly allows for the fact that in practice a single conflicting or counter-instance is never sufficient methodologically to falsify a theory, and that scientific theories are often retained even though much of the available evidence conflicts with them, or is anomalous with respect to them. Scientific theories may, and do, arise genetically in many different ways, and the manner in which a particular scientist comes to formulate a particular theory may be of biographical interest, but it is of no consequence as far as the philosophy of science is concerned.

Popper stresses in particular that there is no unique way, no single method such as induction, which functions as the route to scientific theory, a view which Einstein personally endorsed with his affirmation that 'There is no logical path leading to [the highly universal laws of science]. They can only be reached by intuition, based upon something like an intellectual love of the objects of experience'. Science, in Popper's view, starts with problems rather than with observations - it is, indeed, precisely in the context of grappling with a problems that the scientist makes observations in the first instance: his observations are selectively designed to test the extent to which a given theory functions as a satisfactory solution to a given problem.

On this criterion of demarcation physics, chemistry, and (non-introspective) psychology, amongst others, are sciences, psychoanalysis is a pre-science (i.e. it undoubtedly contains useful and informative truths, but until such time as psychoanalytical theories can be formulated in such a manner as to be falsifiable, they will not attain the status of scientific theories), and astrology and phrenology are pseudo-sciences. Formally, then, Popper's theory of demarcation may be articulated as follows: where a 'basic statement' is to be understood as a particular observation-report, then we may say that a theory is scientific if and only if the class of basic statements relating to it can be divided into the following two non-empty sub-classes: (a) the class of all those basic statements with which it is inconsistent, or which it prohibits - this is the class of its potential falsifiers (i.e. those statements which, if true, falsify the whole theory), and (b) the class of those basic statements with which it is consistent, or which it permits (i.e. those statements which, if true, corroborate it, or bear it out).

The Growth of Human Knowledge

For Popper accordingly, the growth of human knowledge proceeds from our problems and from our attempts to solve them. These attempts involve the formulation of theories which, if they are to explain anomalies which exist with respect to earlier theories, must go beyond existing knowledge and therefore require a leap of the imagination. For this reason, Popper places special emphasis on the role played by the independent creative imagination in the formulation of theory.

The centrality and priority of problems in Popper's account of science is paramount, and it is this which leads him to characterise scientists as 'problem-solvers'. Further, since the scientist begins with problems rather than with observations or 'bare facts', Popper argues that the only logical technique which is an integral part of scientific method is that of the deductive testing of theories which are not themselves the product of any logical operation. In this deductive procedure conclusions are inferred from a tentative hypothesis.

These conclusions are then compared with one another and with other relevant statements to determine whether they falsify or corroborate the hypothesis. Such conclusions are not directly compared with the facts, Popper stresses, simply because there are no 'pure' facts available; all observation-statements are theory-laden, and are as much a function of purely subjective factors (interests, expectations, wishes, etc.) as they are a function of what is objectively real.

How then does the deductive procedure work? Popper specifies four steps:

(a) The first is formal, a testing of the internal consistency of the theoretical system to see if it involves any contradictions.

(b) The second step is semi-formal, the axiomatising of the theory to distinguish between its empirical and its logical elements. In performing this step the scientist makes the logical form of the theory explicit. Failure to do this can lead to category-mistakes - the scientist ends up asking the wrong questions, and searches for empirical data where none are available. Most scientific theories contain analytic (i.e. a priori) and synthetic elements, and it is necessary to axiomatise them in order to distinguish the two clearly.

(c) The third step is the comparing of the new theory with existing ones to determine whether it constitutes an advance upon them. If it does not constitute such an advance, it will not be adopted. If, on the other hand, its explanatory success matches that of the existing theories, and additionally, it explains some hitherto anomalous phenomenon, or solves some hitherto unsolvable problems, it will be deemed to constitute an advance upon the existing theories, and will be adopted.

Thus science involves theoretical progress. However, Popper stresses that we ascertain whether one theory is better than another by deductively testing both theories, rather than by induction. For this reason, he argues that a theory is deemed to be better than another if (while unfalsified) it has greater empirical content, and therefore greater predictive power than its rival. The classic illustration of this in physics was the replacement of Newton's theory of universal gravitation by Einstein's theory of relativity. This elucidates the nature of science as Popper sees it: at any given time there will be a number of conflicting theories or conjecture, some of which will explain more than others. The latter will consequently be provisionally adopted. In short, for Popper any theory X is better than a 'rival' theory Y if X has greater empirical content, and hence greater predictive power, than Y.

(d) The fourth and final step is the testing of a theory by the empirical application of the conclusions derived from it. If such conclusions are shown to be true, the theory is corroborated (but never verified). If the conclusion is shown to be false, then this is taken as a signal that the theory cannot be completely correct (logically the theory is falsified), and the scientist begins his quest for a better theory. He does not, however, abandon the present theory until such time as he has a better one to substitute for it. More precisely, the method of theory-testing is as follows: certain singular propositions are deduced from the new theory - these are predictions, and of special interest are those predictions which are 'risky' (in the sense of being intuitively implausible or of being startlingly novel) and experimentally testable.

From amongst the latter the scientist next selects those which are not derivable from the current or existing theory - of particular importance are those which contradict the current or existing theory. He then seeks a decision as regards these and other derived statements by comparing them with the results of practical applications and experimentation.

If the new predictions are borne out, then the new theory is corroborated (and the old one falsified), and is adopted as a working hypothesis. If the predictions are not borne out, then they falsify the theory from which they are derived.

Thus Popper retains an element of empiricism: for him scientific method does involve making an appeal to experience. But unlike traditional empiricists, Popper holds that experience cannot determine theory (i.e. we do not argue or infer from observation to theory), it rather delimits it: it shows which theories are false, not which theories are true. Moreover, Popper also rejects the empiricist doctrine that empirical observations are, or can be, infallible, in view of the fact that they are themselves theory-laden.

The general picture of Popper's philosophy of science, then is this: Hume's philosophy demonstrates that there is a contradiction implicit in traditional empiricism, which holds both that all knowledge is derived from experience and that universal propositions (including scientific laws) are verifiable by reference to experience. The contradiction, which Hume himself saw clearly, derives from the attempt to show that, notwithstanding the open-ended nature of experience, scientific laws may be construed as empirical generalisations which are in some way finally confirmable by a 'positive' experience.

Popper eliminates the contradiction by rejecting the first of these principles and removing the demand for empirical verification in favour of empirical falsification in the second. Scientific theories, for him, are not inductively inferred from experience, nor is scientific experimentation carried out with a view to verifying or finally establishing the truth of theories; rather, all knowledge is provisional, conjectural, hypothetical - we can never finally prove our scientific theories, we can merely (provisionally) confirm or (conclusively) refute them; hence at any given time we have to choose between the potentially infinite number of theories which will explain the set of phenomena under investigation.

Faced with this choice, we can only eliminate those theories which are demonstrably false, and rationally choose between the remaining, unfalsified theories. Hence Popper's emphasis on the importance of the critical spirit to science - for him critical thinking is the very essence of rationality. For it is only by critical thought that we can eliminate false theories, and determine which of the remaining theories is the best available one, in the sense of possessing the highest level of explanatory force and predictive power. It is precisely this kind of critical thinking which is conspicuous by its absence in contemporary Marxism and in psychoanalysis

Probability, Knowledge and Verisimilitude

In the view of many social scientists, the more probable a theory is, the better it is, and if we have to choose between two theories which are equally strong in terms of their explanatory power, and differ only in that one is probable and the other is improbable, then we should choose the former. Popper rejects this. Science, or to be precise, the working scientist, is interested, in Popper's view, in theories with a high informative content, because such theories possess a high predictive power and are consequently highly testable.

But if this is true, Popper argues, then, paradoxical as it may sound, the more improbable a theory is the better it is scientifically, because the probability and informative content of a theory vary inversely - the higher the informative content of a theory the lower will be its probability, for the more information a statement contains, the greater will be the number of ways in which it may turn out to be false. Thus the statements which are of special interest to the scientist are those with a high informative content and (consequentially) a low probability, which nevertheless come close to the truth. Informative content, which is in inverse proportion to probability, is in direct proportion to testability. Consequently the severity of the test to which a theory can be subjected, and by means of which it is falsified or corroborated, is all-important.

For Popper, all scientific criticism must be piecemeal, i.e. he holds that it is not possible to question every aspect of a theory at once. More precisely, while attempting to resolve a particular problem a scientist of necessity accepts all kinds of things as unproblematic. These things constitute what Popper terms the 'background knowledge'. However, he stresses that the background knowledge is not knowledge in the sense of being conclusively established; it may be challenged at any time, especially if it is suspected that its uncritical acceptance may be responsible difficulties which are subsequently encountered. Nevertheless, it is clearly not possible to question both the theory and the background knowledge at the same time (e.g. in conducting an experiment the scientist of necessity assumes that the apparatus used is in working order).

How then can one be certain that one is questioning the right thing? The Popperian answer is that we cannot have absolute certainty here, but repeated tests usually show where the trouble lies. Even observation statements, Popper maintains, are fallible, and science in his view is not a quest for certain knowledge, but an evolutionary process in which hypotheses or conjectures are imaginatively proposed and tested in order to explain facts or to solve problems. Popper emphasises both the importance of questioning the background knowledge when the need arises, and the significance of the fact that observation-statements are theory-laden, and hence fallible. For while falsifiability is simple as a logical principle, in practice it is exceedingly complicated - no single observation can ever be taken to falsify a theory, for there is always the possibility (a) that the observation itself is mistaken, or (b) that the assumed background knowledge is faulty or defective.

Popper was initially uneasy with the concept of truth, and in his earliest writings he avoided asserting that a theory which is corroborated is true - for clearly if every theory is an open-ended hypothesis, as he maintains, then ipso facto it has to be at least potentially false. For this reason Popper restricted himself to the contention that a theory which is falsified is false and is known to be such, and that a theory which replaces a falsified theory (because it has a higher empirical content than the latter, and explains what has falsified it) is a 'better theory' than its predecessor.

However, he came to accept Tarski's reformulation of the correspondence theory of truth, and in Conjectures and Refutations (1963) he integrated the concepts of truth and content to frame the metalogical concept of 'truthlikeness' or 'verisimilitude'. A 'good' scientific theory, Popper thus argued, has a higher level of verisimilitude than its rivals, and he explicated this concept by reference to the logical consequences of theories. A theory's content is the totality of its logical consequences, which can be divided into two classes: there is the 'truth-content' of a theory, which is the class of true propositions which may be derived from it, on the one hand, and the 'falsity-content' of a theory, on the other hand, which is the class of the theory's false consequences (this latter class may of course be empty, and in the case of a theory which is true is necessarily empty).

Popper offered two methods of comparing theories in terms of verisimilitude, the qualitative and quantitative definitions. On the qualitative account, Popper asserted:

Assuming that the truth-content and the falsity-content of two theories t1 and t2 are comparable, we can say that t2 is more closely similar to the truth, or corresponds better to the facts, than t1, if and only if either

(a) the truth-content but not the falsity-content of t2 exceeds that of t1,
(b) the falsity-content of t1, but not its truth-content, exceeds that of t2.
(Conjectures and Refutations, 233).
Here, verisimilitude is defined in terms of subclass relationships: t2 has a higher level of verisimilitude than t1 if and only if their truth- and falsity-contents are comparable through subclass relationships, and either (a) t2's truth-content includes t1's and t2's falsity-content, if it exists, is included in, or is the same as, t1's, or (b) t2's truth-content includes or is the same as t1's and t2's falsity-content, if it exists, is included in t1's.

On the quantitative account, verisimilitude is defined by assigning quantities to contents, where the index of the content of a given theory is it logical improbability (given again that content and probability vary inversely). Formally, then, Popper defines the quantitative verisimilitude which a statement 'a' possesses by means of a formula:

Vs(a) = CtT(a) - CtF(a),

where Vs(a) represents the verisimilitude of 'a', CtT(a) is a measure of the truth-content of 'a', and CtF(a) is a measure of its falsity-content.

The utilisation of either method of computing verisimilitude shows, Popper held, that even if a theory t2 with a higher content than a rival theory t1 is subsequently falsified, it can still legitimately be regarded as a better theory than t1, and 'better' is here now understood to mean t2 is closer to the truth than t1.

Thus scientific progress involves, on this view, the abandonment of partially true, but falsified, theories, for theories with a higher level of verisimilitude, i.e., which approach more closely to the truth. I

n this way, verisimilitude allowed Popper to mitigate what many saw as the pessimism of an anti-inductivist philosophy of science which held that most, if not all scientific theories are false, and that a true theory, even if discovered, could not be known to be such. With the introduction of the new concept, Popper was able to represent this as an essentially optimistic position in terms of which we can legitimately be said to have reason to believe that science makes progress towards the truth through the falsification and corroboration of theories. Scientific progress, in other words, could now be represented as progress towards the truth, and experimental corroboration could be seen an indicator of verisimilitude.

However, in the 1970's a series of papers published by researchers such as Miller, Tichý, and Grünbaum in particular revealed fundamental defects in Popper's formal definitions of verisimilitude. The significance of this work was that verisimilitude is largely important in Popper's system because of its application to theories which are known to be false. In this connection, Popper had written:

Ultimately, the idea of verisimilitude is most important in cases where we know that we have to work with theories which are at best approximations—that is to say, theories of which we know that they cannot be true. (This is often the case in the social sciences). In these cases we can still speak of better or worse approximations to the truth (and we therefore do not need to interpret these cases in an instrumentalist sense).
(Conjectures and Refutations, 235).

For these reasons, the deficiencies discovered by the critics in Popper's formal definitions were seen by many as devastating, precisely because the most significant of these related to the levels of verisimilitude of false theories. In 1974, Miller and Tichý, working independently of each other, demonstrated that the conditions specified by Popper in his accounts of both qualitative and quantitative verisimilitude for comparing the truth- and falsity-contents of theories can be satisfied only when the theories are true. In the crucially important case of false theories, however, Popper's definitions are formally defective.

For while Popper had believed that verisimilitude intersected positively with his account of corroboration, in the sense that he viewed an improbable theory which had withstood critical testing as one the truth-content of which is great relative to rival theories, while its falsity-content (if it exists) would be relatively low, Miller and Tichý proved, on the contrary, that in the case of a false theory t2 which has excess content over a rival theory false t1 both the truth-content and the falsity-content of t2 will exceed that of t1. With respect to theories which are false, therefore, Popper's conditions for comparing levels of verisimilitude, whether in quantitative and qualitative terms, can never be met.

Commentators on Popper, with few exceptions, had initially attached little importance to his theory of verisimilitude. However, after the failure of Popper's definitions in 1974, some critics came to see it as central to his philosophy of science, and consequentially held that whole edifice of the latter had been subverted. For his part, Popper's response was two-fold.

In the first place, while acknowledging the deficiencies in his own formal account ('my main mistake was my failure to see at once that … if the content of a false statement a exceeds that of a statement b, then the truth-content of a exceeds the truth-content of b, and the same holds of their falsity-contents', Objective Knowledge, 371), Popper argued that 'I do think that we should not conclude from the failure of my attempts to solve the problem [of defining verisimilitude] that the problem cannot be solved' (Objective Knowledge, 372), a point of view which was to precipitate more than two decades of important technical research in this field.

At another, more fundamental level, he moved the task of formally defining the concept from centre-stage in his philosophy of science, by protesting that he had never intended to imply 'that degrees of verisimilitude ... can ever be numerically determined, except in certain limiting cases' (Objective Knowledge, 59), and arguing instead that the chief value of the concept is heuristic and intuitive, in which the absence of an adequate formal definition is not an insuperable impediment to its utilisation in the actual appraisal of theories relativised to problems in which we have an interest. The thrust of the latter strategy seems to many to genuinely reflect the significance of the concept of verisimilitude in Popper's system, but it has not satisfied all of his critic

Social and Political Thought - The Critique of Historicism and Holism

Given Popper's personal history and background, it is hardly surprising that he developed a deep and abiding interest in social and political philosophy. However, it is worth emphasising that his angle of approach to these fields is through a consideration of the nature of the social sciences which seek to describe and explicate them systematically, particularly history. It is it this context that he offers an account of the nature of scientific prediction, which in turn allows him a point of departure for his attack upon totalitarianism and all its intellectual supports, especially holism and historicism.

In this context holism is to be understood as the view that human social groupings are greater than the sum of their members, that such groupings are 'organic' entities in their own right, that they act on their human members and shape their destinies, and that they are subject to their own independent laws of development. Historicism, which is closely associated with holism, is the belief that history develops inexorably and necessarily according to certain principles or rules towards a determinate end (as for example in the dialectic of Hegel, which was adopted and implemented by Marx). The link between holism and historicism is that the holist believes that individuals are essentially formed by the social groupings to which they belong, while the historicist - who is usually also a holist - holds that we can understand such a social grouping only in terms of the internal principles which determine its development.

These beliefs lead to what Popper calls 'The Historicist Doctrine of the Social Sciences', the views (a) that the principal task of the social sciences is to make predictions about the social and political development of man, and (b) that the task of politics, once the key predictions have been made, is, in Marx's words, to lessen the 'birth pangs' of future social and political developments. Popper thinks that this view of the social sciences is both theoretically misconceived (in the sense of being based upon a view of natural science and its methodology which is totally wrong), and socially dangerous, as it leads inevitably to totalitarianism and authoritarianism - to centralised governmental control of the individual and the attempted imposition of large-scale social planning.

Against this Popper strongly advances the view that any human social grouping is no more (or less) than the sum of its individual members, that what happens in history is the (largely unplanned and unforeseeable) result of the actions of such individuals, and that large scale social planning to an antecedently conceived blueprint is inherently misconceived - and inevitably disastrous - precisely because human actions have consequences which cannot be foreseen. Popper, then, is an historical indeterminist, insofar as he holds that history does not evolve in accordance with intrinsic laws or principles, that in the absence of such laws and principles unconditional prediction in the social sciences is an impossibility, and that there is no such thing as historical necessity.

The link between Popper's theory of knowledge and his social philosophy is his fallibilism - just as we make theoretical progress in science by deliberately subjecting our theories to critical scrutiny, and abandoning those which have been falsified, so too, Popper holds, the critical spirit can and should be sustained at the social level. More specifically, the open society can be brought about only if it is possible for the individual citizen to evaluate critically the consequences of the implementation of government policies, which can then be abandoned or modified in the light of such critical scrutiny - in such a society, the rights of the individual to criticise administrative policies will be formally safeguarded and upheld, undesirable policies will be eliminated in a manner analogous to the elimination of falsified scientific theories, and differences between people on social policy will be resolved by critical discussion and argument rather than by force.

The open society as thus conceived of by Popper may be defined as 'an association of free individuals respecting each other's rights within the framework of mutual protection supplied by the state, and achieving, through the making of responsible, rational decisions, a growing measure of humane and enlightened life' (Levinson, R.B. In Defense of Plato, 17). As such, Popper holds, it is not a utopian ideal, but an empirically realised form of social organisation which, he argues, is in every respect superior to its (real or potential) totalitarian rivals. But he does not engage in a moral defence of the ideology of liberalism; rather his strategy is the much deeper one of showing that totalitarianism is typically based upon historicist and holist presuppositions, and of demonstrating that these presuppositions are fundamentally incoherent.

Scientific Knowledge, History, and Prediction

At a very general level, Popper argues that historicism and holism have their origins in what he terms 'one of the oldest dreams of mankind - the dream of prophecy, the idea that we can know what the future has in store for us, and that we can profit from such knowledge by adjusting our policy to it.' (Conjectures and Refutations, 338). This dream was given further impetus, he speculates, by the emergence of a genuine predictive capability regarding such events as solar and lunar eclipses at an early stage in human civilisation, which has of course become increasingly refined with the development of the natural sciences and their concomitant technologies.

The kind of reasoning which has made, and continues to make, historicism plausible may, on this account, be reconstructed as follows: if the application of the laws of the natural sciences can lead to the successful prediction of such future events as eclipses, then surely it is reasonable to infer that knowledge of the laws of history as yielded by a social science or sciences (assuming that such laws exist) would lead to the successful prediction of such future social phenomena as revolutions? Why should it be possible to predict an eclipse, but not a revolution? Why can we not conceive of a social science which could and would function as the theoretical natural sciences function, and yield precise unconditional predictions in the appropriate sphere of application? These are amongst the questions which Popper seeks to answer, and in doing so, to show that they are based upon a series of misconceptions about the nature of science, and about the relationship between scientific laws and scientific prediction.

His first argument may be summarised as follows: in relation to the critically important concept of prediction, Popper makes a distinction between what he terms 'conditional scientific predictions', which have the form 'If X takes place, then Y will take place', and 'unconditional scientific prophecies', which have the form 'Y will take place'. Contrary to popular belief, it is the former rather than the latter which are typical of the natural sciences, which means that typically prediction in natural science is conditional and limited in scope - it takes form of hypothetical assertions stating that certain specified changes will come about if particular specified events antecedently take place.

This is not to deny that 'unconditional scientific prophecies', such as the prediction of eclipses, for example, do take place in science, and that the theoretical natural sciences make them possible. However, Popper argues that (a) these unconditional prophecies are not characteristic of the natural sciences, and (b) that the mechanism whereby they occur, in the very limited way in which they do, is not understood by the historicist.

What is the mechanism which makes unconditional scientific prophecies possible? The answer is that such prophecies can sometimes be derived from a combination of conditional predictions (themselves derived from scientific laws) and existential statements specifying that the conditions in relation to the system being investigated are fulfilled. Schematically, this can be represented as follows:

[C.P. + E.S.] = U.P.
where C.P. = Conditional Prediction; E.S. = Existential Statement; U.P. = Unconditional Prophecy. The most common examples of unconditional scientific prophecies in science relate to the prediction of such phenomena as lunar and solar eclipses and comets.
Given, then, that this is the mechanism which generates unconditional scientific prophecies, Popper makes two related claims about historicism: (a) That the historicist does not in fact derive his unconditional scientific prophecies in this manner from conditional predictions, and (b) the historicist cannot do so because long-term unconditional scientific prophecies can be derived from conditional predictions only if they apply to systems which are well-isolated, stationary, and recurrent (like our solar system). Such systems are quite rare in nature, and human society is most emphatically not one of them.

This, then, Popper argues, is the reason why it is a fundamental mistake for the historicist to take the unconditional scientific prophecies of eclipses as being typical and characteristic of the predictions of natural science - in fact such predictions are possible only because our solar system is a stationary and repetitive system which is isolated from other such systems by immense expanses of empty space. The solar system aside, there are very few such systems around for scientific investigation - most of the others are confined to the field of biology, where unconditional prophecies about the life-cycles of organisms are made possible by the existence of precisely the same factors. Thus one of the fallacies committed by the historicist is to take the (relatively rare) instances of unconditional prophecies in the natural science as constituting the essence of what scientific prediction is, to fail to see that such prophecies apply only to systems which are isolated, stationary, and repetitive, and to seek to apply the method of scientific prophecy to human society and human history.

The latter, of course, is not an isolated system (in fact it's not a system at all), it is constantly changing, and it continually undergoes rapid, non-repetitive development. In the most fundamental sense possible, every event in human history is discrete, novel, quite unique, and ontologically distinct from every other historical event. For this reason, it is impossible in principle that unconditional scientific prophecies could be made in relation to human history - the idea that the successful unconditional prediction of eclipses provides us with reasonable grounds for the hope of successful unconditional prediction regarding the evolution of human history turns out to be based upon a gross misconception, and is quite false. As Popper himself concludes, 'The fact that we predict eclipses does not, therefore, provide a valid reason for expecting that we can predict revolutions.' (Conjectures and Refutations, 340).

Immutable Laws and Contingent Trends

This argument is one of the strongest that has ever been brought against historicism, cutting, as it does, right to the heart of one of its main theoretical presuppositions. However, it is not Popper's only argument against it. An additional mistake which he detects in historicism is the failure of the historicist to distinguish between scientific laws and trends, which is also frequently accompanied by a simple logical fallacy.

The fallacy is that of inferring from the fact that our understanding of any (past) historical event - such as, for example, the French Revolution - is in direct proportion to our knowledge of the antecedent conditions which led to that event, that knowledge of all the antecedent conditions of some future event is possible, and that such knowledge would make that future event precisely predictable.

For the truth is that the number of factors which predate and lead to the occurrence of any event, past, present, or future, is indefinitely large, and therefore knowledge of all of these factors is impossible, even in principle. What gives rise to the fallacy is the manner in which the historian (necessarily) selectively isolates a finite number of the antecedent conditions of some past event as being of particular importance, which are then somewhat misleadingly termed 'the causes' of that event, when in fact what this means is that they are the specific conditions which a particular historian or group of historians take to be more relevant than any other of the indefinitely large number of such conditions (for this reason, most historical debates range over the question as to whether the conditions thus specified are the right ones).

While this kind of selectivity may be justifiable in relation to the treatment of any past event, it has no basis whatsoever in relation to the future - if we now select, as Marx did, the 'relevant' antecedent conditions for some future event, the likelihood is that we will select wrongly.

The historicist's failure to distinguish between scientific laws and trends is equally destructive of his cause. This failure makes him think it possible to explain change by discovering trends running through past history, and to anticipate and predict future occurrences on the basis of such observations. Here Popper points out that there is a critical difference between a trend and a scientific law, failure to observe which is fatal.

For a scientific law is universal in form, while a trend can be expressed only as a singular existential statement. This logical difference is crucial because unconditional predictions, as we have already seen, can be based only upon conditional ones, which themselves must be derived from scientific laws. Neither conditional nor unconditional predictions can be based upon trends, because these may change or be reversed with a change in the conditions which gave rise to them in the first instance.

As Popper puts it, there can be no doubt that 'the habit of confusing trends with laws, together with the intuitive observation of trends such as technical progress, inspired the central doctrines of ... historicism.' (The Poverty of Historicism, 116). Popper does not, of course, dispute the existence of trends, nor does he deny that the observation of trends can be of practical utility value - but the essential point is that a trend is something which itself ultimately stands in need of scientific explanation, and it cannot therefore function as the frame of reference in terms of which anything else can be scientifically explained or predicted.

A point which connects with this has to do with the role which the evolution of human knowledge has played in the historical development of human society. It is incontestable that, as Marx himself observed, there has been a causal link between the two, in the sense that advances in scientific and technological knowledge have given rise to widespread global changes in patterns of human social organisation and social interaction, which in turn have led to social structures (e.g. educational systems) which further growth in human knowledge.

In short, the evolution of human history has been strongly influenced by the growth of human knowledge, and it is extremely likely that this will continue to be the case - all the empirical evidence suggests that the link between the two is progressively consolidating. However, this gives rise to further problems for the historicist. In the first place, the statement that 'if there is such a thing as growing human knowledge, then we cannot anticipate today what we shall know only tomorrow' is, Popper holds, intuitively highly plausible. Moreover, he argues, it is logically demonstrable by a consideration of the implications of the fact that no scientific predictor, human or otherwise, can possibly predict, by scientific methods, its own future results. From this it follows, he holds, that 'no society can predict, scientifically, its own future states of knowledge' (The Poverty of Historicism, vii).

Thus, while the future evolution of human history is extremely likely to be influenced by new developments in human knowledge, as it always has in the past, we cannot now scientifically determine what such knowledge will be. From this it follows that if the future holds any new discoveries or any new developments in the growth of our knowledge (and given the fallible nature of the latter, it is inconceivable that it does not), then it is impossible for us to predict them now, and it is therefore impossible for us to predict the future development of human history now, given that the latter will, at least in part, be determined by the future growth of our knowledge. Thus once again historicism collapses - the dream of a theoretical, predictive science of history is unrealisable, because it is an impossible dream.

Popper's arguments against holism, and in particular his arguments against the propriety of large-scale planning of social structures, are interconnected with his demonstration of the logical shortcomings of the presuppositions of historicism. Such planning (which actually took place, of course, in the USSR, in China, and in Cambodia, for example, under totalitarian regimes which accepted forms of historicism and holism), Popper points out, is necessarily structured in the light of the predictions which have been made about future history on the basis of the so-called 'laws' which historicists such as Marx and Mao claimed to have discovered in relation to human history.

Accordingly, recognition that there are no such laws, and that unconditional predictions about future history are based, at best, upon nothing more substantial than the observation of contingent trends, shows that, from a purely theoretical as well as a practical point of view, large-scale social planning is indeed a recipe for disaster. In summary, unconditional large-scale planning for the future is theoretically as well as practically misguided, because, again, part of what we are planning for is our future knowledge, and our future knowledge is not something which we can in principle now possess - we cannot adequately plan for unexpected advances in our future knowledge, or for the effects which such advances will have upon society as a whole.

The acceptance of historical indeterminism, then, as the only philosophy of history which is commensurate with a proper understanding of the nature of scientific knowledge, fatally undermines both historicism and holism.

Popper's critique of both historicism and holism is balanced, on the positive side, by his strong defence of the open society, the view, again, that a society is equivalent to the sum of its members, that the actions of the members of society serve to fashion and to shape it, not conversely, and that the social consequences of intentional actions are very often, and very largely, unintentional.

This is why Popper himself advocates what he (rather unfortunately) terms 'piecemeal social engineering' as the central mechanism for social planning - for in utilising this mechanism intentional actions are directed to the achievement of one specific goal at a time, which makes it possible to monitor the situation to determine whether adverse unintended effects of intentional actions occur, in order to correct and readjust when this proves necessary. This, of course parallels precisely the critical testing of theories in scientific investigation.

This approach to social planning (which is explicitly based upon the premise that we do not, because we cannot, know what the future will be like) encourages attempts to put right what is problematic in society - generally-acknowledged social ills - rather than attempts to impose some preconceived idea of the 'good' upon society as a whole. For this reason, in a genuinely open society piecemeal social engineering goes hand-in-hand for Popper with negative utilitarianism (the attempt to minimise the amount of misery, rather than, as with positive utilitarianism, to attempt to maximise the amount of happiness).

The state, he holds, should concern itself with the task of progressively formulating and implementing policies designed to deal with the social problems which actually confront it, with the goal of eliminating human misery and suffering to the highest possible degree. The positive task of increasing social and personal happiness, by contrast, can and should be should be left to individual citizens (who may, of course, act collectively to this end), who, unlike the state, have at least a chance of achieving this goal, but who in a free society are rarely in a position to systematically subvert the rights of others in the pursuit of idealised objectives. Thus in the final analysis for Popper the activity of problem-solving is as definitive of our humanity at the level of social and political organisation as it is at the level of science, and it is this key insight which unifies and integrates the broad spectrum of his thought.

Critical Evaluation

While it cannot be said that Popper was a modest man, he took criticism of his theories very seriously, and spent much of his time in his later years endeavouring to show that such criticisms were either based upon misunderstandings, or that his theories could, without loss of integrity, be made compatible with new and important insights (such as Kuhn's distinction between normal and revolutionary science). The following is a summary of some of the main criticisms which he has had to address.

1. Popper professes to be anti-conventionalist, and his commitment to the correspondence theory of truth places him firmly within the realist's camp. Yet, following Kant, he strongly repudiates the positivist/empiricist view that basic statements (i.e. present-tense observation statements about sense-data) are infallible, and argues convincingly that such basic statements are not mere 'reports' of passively registered sensations.

Rather they are descriptions of what is observed as interpreted by the observer with reference to a determinate theoretical framework. This is why Popper repeatedly emphasises that basic statements are not infallible, and it indicates what he means when he says that they are 'theory laden' - perception itself is an active process, in which the mind assimilates data by reference to an assumed theoretical backdrop. He accordingly asserts that basic statements themselves are open-ended hypotheses: they have a certain causal relationship with experience, but they are not determined by experience, and they cannot be verified or confirmed by experience.

However, this poses a difficulty regarding the consistency of Popper's theory: if a theory X is to be genuinely testable (and so scientific) it must be possible to determine whether or not the basic propositions which would, if true, falsify it, are actually true or false (i.e. whether its potential falsifiers are actual falsifiers). But how can this be known, if such basic statements cannot be verified by experience? Popper's answer is that 'basic statements are not justifiable by our immediate experiences, but are .... accepted by an act, a free decision' (Logic of Scientific Discovery, 109).

However, and notwithstanding Popper's claims to the contrary, this itself seems to be a refined form of conventionalism - it implies that it is almost entirely an arbitrary matter whether it is accepted that a potential falsifier is an actual one, and consequently that the falsification of a theory is itself the function of a 'free' and arbitrary act. It also seems very difficult to reconcile this with Popper's view that science progressively moves closer to the truth, conceived of in terms of the correspondence theory, for this kind of conventionalism is inimical to this (classical) conception of truth.

2. As Lakatos has pointed out, Popper's theory of demarcation hinges quite fundamentally on the assumption that there are such things as critical tests, which either conclusively falsify a theory, or give it a strong measure of corroboration. Popper himself is fond of citing, as an example of such a critical test, the resolution, by Adams and Leverrier, of the problem which the anomalous orbit of Uranus posed for nineteenth century astronomers. Both men independently came to the conclusion that, assuming Newtonian mechanics to be precisely correct, the observed divergence in the elliptical orbit of Uranus could be explained if the existence of a seventh, as yet unobserved outer planet was posited.

Further, they were able, again within the framework of Newtonian mechanics, to calculate the precise position of the 'new' planet. Thus when subsequent research by Galle at the Berlin observatory revealed that such a planet (Neptune) did in fact exist, and was situated precisely where Adams and Leverrier had calculated, this was hailed as by all and sundry as magnificent triumph for Newtonian physics: in Popperian terms, Newton's theory had been subjected to a critical test, and had passed with flying colours. Popper himself refers to this strong corroboration of Newtonian physics as 'the most startling and convincing success of any human intellectual achievement'.

Yet Lakatos flatly denies that there are critical tests, in the Popperian sense, in science, and argues the point convincingly by turning the above example of an alleged critical test on its head. What, he asks, would have happened if Galle had not found the planet Neptune? Would Newtonian physics have been abandoned, or would Newton's theory have been falsified?

The answer is clearly not, for Galle's failure could have been attributed to any number of causes other than the falsity of Newtonian physics (e.g. the interference of the earth's atmosphere with the telescope, the existence of an asteroid belt which hides the new planet from the earth, etc). The point here is that the 'falsification/corroboration' disjunction offered by Popper is far too logically neat: non-corroboration is not necessarily falsification, and falsification of a high-level scientific theory is never brought about by an isolated observation or set of observations. Such theories are, it is now generally accepted, highly resistant to falsification. They are falsified, if at all, Lakatos argues, not by Popperian critical tests, but rather within the elaborate context of the research programmes associated with them gradually grinding to a halt, with the result that an ever-widening gap opens up between the facts to be explained, and the research programmes themselves (Lakatos, I. The Methodology of Scientific Research Programmes, passim).

Popper's distinction between the logic of falsifiability and its applied methodology does not in the end do full justice to the fact that all high-level theories grow and live despite the existence of anomalies (i.e. events/phenomena which are incompatible with the theories). The existence of such anomalies is not usually taken by the working scientist as an indication that the theory in question is false; on the contrary, he will usually, and necessarily, assume that the auxiliary hypotheses which are associated with the theory can modified to incorporate, and explain, existing anomalies.

3. Scientific laws are expressed by universal statements (i.e. they take the logical form 'All A's are X', or some equivalent) which are therefore concealed conditionals - they have to be understood as hypothetical statements asserting what would be the case under certain ideal conditions. In themselves they are not existential in nature. Thus 'All A's are X' means 'If anything is an A, then it is X'. Since scientific laws are non-existential in nature, they logically cannot imply any basic statements, since the latter are explicitly existential.

The question arises, then, as to how any basic statement can falsify a scientific law, given that basic statements are not deducible from scientific laws in themselves? Popper answers that scientific laws are always taken in conjunction with statements outlining the 'initial conditions' of the system under investigation; these latter, which are singular existential statements, do, when combined with the scientific law, yield hard and fast implications. Thus, the law 'All A's are X', together with the initial condition statement 'There is an A at Y', yields the implication 'The A at Y is X', which, if false, falsifies the original law.

This reply is adequate only if it true, as Popper assumes, that singular existential statements will always do the work of bridging the gap between a universal theory and a prediction. Hilary Putnam in particular has argued that this assumption is false, in that in some cases at least the statements required to bridge this gap (which he calls 'auxiliary hypotheses') are general rather than particular, and consequently that when the prediction turns out to be false we have no way of knowing whether this is due to the falsity of the scientific law or the falsity of the auxiliary hypotheses. The working scientist, Putnam argues, always initially assumes that it is the latter, which shows not only that scientific laws are, contra Popper, highly resistant to falsification, but also why they are so highly resistant to falsification.

Popper's final position is that he acknowledges that it is impossible to discriminate science from non-science on the basis of the falsifiability of the scientific statements alone; he recognizes that scientific theories are predictive, and consequently prohibitive, only when taken in conjunction with auxiliary hypotheses, and he also recognizes that readjustment or modification of the latter is an integral part of scientific practice. Hence his final concern is to outline conditions which indicate when such modification is genuinely scientific, and when it is merely ad hoc.

This is itself clearly a major alteration in his position, and arguably represents a substantial climb down on his part: Marxism can no longer be dismissed as 'unscientific' simply because its advocates preserved the theory from falsification by modifying it (for in general terms, such a procedure, it now transpires, is perfectly respectable scientific practice). It is now condemned as unscientific by Popper because the only rationale for the modifications which were made to the original theory was to ensure that it evaded falsification, and so such modifications were ad hoc, rather than scientific. This contention - though not at all implausible - has, to hostile eyes, a somewhat contrived air about it, and is unlikely to worry the convinced Marxist. On the other hand, the shift in Popper's own basic position is taken by some critics as an indicator that falsificationism, for all its apparent merits, fares no better in the final analysis than verificationism.

Stanford Encyclopedia of Philosophy, 1997