Quotes about doubt
page 4

BBC radio broadcast, March 28, 1949. http://www.joh.cam.ac.uk/library/special_collections/hoyle/exhibition/radio/ Reprinted in April 1949 in The Listener, a BBC magazine.

Source: The Idea of History (1946), p. 10

Source: 1950s, Portraits from Memory and Other Essays (1956), p. 159

In revised edition, chapter 78, p. 401, The Autobiography of Mark Twain, 1959, Charles Neider, Harper & Row
Mark Twain's Autobiography (1924)

The War as I Knew it https://books.google.com/books?id=2A4BPpDQTfcC&pg=PA49 (1974), p.49.

Philosophical Remarks (1991), Part III (27), pp.66-67
Attributed from posthumous publications

Source: Thank You and You're Welcome (2009), p.3-4

Interview on Bebbe Grillo's Blog http://www.beppegrillo.it/eng/2007/01/stiglitz.html, January 2007.
"College Master Looks at His World: Author Davies Finds Youth Little Changed".
Conversations with Robertson Davies (1989)

Talk titled "U.S. Foreign Policy in a Globalized World" at Johns Hopkins University, Maryland, March 13, 2000 https://web.archive.org/web/20021220030406/http://www.gseis.ucla.edu/faculty/kellner/ed270/multimedia.html.
Quotes 2000s, 2000

Interview with Putra Nababan in the White House https://www.youtube.com/watch?v=38sFgxBhpkU (March 2010)
2010

Alfred Cortot: Master Class on Schumann Kinderszenen (1953) http://www.youtube.com/watch?v=rNUNNNNj_Qw

Introduction
Postmodernism: Or, The Cultural Logic of Late Capitalism (1991)

In response to a question "In what circumstances would the president have constitutional authority to bomb Iran without seeking a use-of-force authorization from Congress?"
Boston Globe questionnaire on Executive Power, December 20, 2007. http://www.ontheissues.org/Archive/2007_Exec_Power_Barack_Obama.htm
2007

"If Black English Isn't a Language, Then Tell Me, What Is?" http://www.nytimes.com/books/98/03/29/specials/baldwin-english.html in "The New York Times (29 July 1979)

Source: The Limits of State Action (1792), Ch. 1

"Further Reflections on the Conversations of Our Time" (1997), which received first place in the Philosophy and Literature Bad Writing Contest

Said to Enver Hoxha, on their second meeting together in March-April 1949, as quoted in Hoxha's (1986) The Artful Albanian, (Chatto & Windus, London), ISBN 0701129700
Contemporary witnesses

9 September 1950
Source: 1946 - 1953, "Song of herself"; interviews by Olga Campos, Sept. 1950, Chapter 'My life', p. 64

1980s, First term of office (1981–1985), Abortion and the Conscience of the Nation (1983)

Source: The Foundations of Leninism, Ch.8

However, that wouldn't work in Poland or New York City, where the Jews are of an inferior strain, & so numerous that they would essentially modify the physical type.
Letter to Natalie H. Wooley (22 November 1934), in Selected Letters V, 1934-1937 edited by August Derleth and Donald Wandrei, p. 77
Non-Fiction, Letters

But since the Lecompton bill no Democrat, within my experience, has ever pretended that he could see the end. That cry has been dropped. They themselves do not pretend, now, that the agitation of this subject has come to an end yet.
1860s, Allow the humblest man an equal chance (1860)

The Ballot or the Bullet (1964), Speech in Cleveland, Ohio (April 3, 1964)

“Epilogue”, from De-triumphant March (1960)
Source: Building Entopia - 1975, Chapter 4, Definition of Entopia, p. 38

On the job of the U.S. President and the need of good advisers and staff
2017, Final News Conference as President (January 2017)

1860s, "If Slavery Is Not Wrong, Nothing Is Wrong" (1864)

“There are questions which, once approached, either isolate you or kill you outright.”
On the Heights of Despair (1934)

As quoted in The Decline and Fall of Nazi Germany and Imperial Japan (1997) by Hans Dollinger, p. 242

2009, A New Beginning (June 2009)

PGA Tour, Inc. v. Martin, 532 U.S. 661 http://caselaw.lp.findlaw.com/scripts/getcase.pl?court=us&vol=000&invol=00-24 (2001) (dissenting).
2000s

1850s, Letter to Joshua F. Speed (1855)

Source: Culture and Value (1980), p. 15e

"16 Questions on the Assassination" http://karws.gso.uri.edu/JFK/The_critics/Russell/Sixteen_questions_Russell.html in The Minority of One, ed. M.S. Arnoni (1964-09-06), pp. 6-8
1960s
Source: Modern Astrophysics, London, 1924, Chapter XIV, page 182
This quote is a paraphrase of the contents of the first chapter of Discourse on Voluntary Servitude. The quote appears in an edition titled Politics of Obedience: The Discourse of Voluntary Servitude edited by Murray Rothbard and Harry Kurz (1975), p. 39 http://books.google.com/books?id=6o-8P3iqf7IC&pg=PA39
Disputed

6.51
1920s, Tractatus Logico-Philosophicus (1922)

1860s, Allow the humblest man an equal chance (1860)

Source: Speech on Reform Bill of 1867, Edinburgh, Scotland (29 October 1867); quoted in William Flavelle Monypenny and George Earle Buckle, The Life of Benjamin Disraeli, Earl of Beaconsfield. Volume II. 1860–1881 (London: John Murray, 1929), p. 291.

Source: Lectures on Negative Dialectics (1965-66), p. 16

Third presidential debate http://abcnews.go.com/Politics/OTUS/presidential-debate-full-transcript/story?id=17538888, Lynn University, Boca Raton, Florida, , quoted in * 2012-10-23
Horses, bayonets, and battleships
Prachi
Gupta
Salon
http://www.salon.com/2012/10/23/horses_bayonets_and_battleships/
2012-10-24
2012

Speech http://hansard.millbanksystems.com/commons/1845/apr/11/maynooth-college in the House of Commons (11 April 1845).
1840s

Science in the Dock (2011), 2, Chomsky.info, March 1, 2006, August 16, 2011 http://www.chomsky.info/debates/20060301.htm,
Quotes 2010s, 2011

Vers une architecture [Towards an Architecture] (1923)

Marginalia http://www.easylit.com/poe/comtext/prose/margin.shtml (November 1844)

Gunasekara, quoted on BBC News, What is the Kumaratunga Legacy? http://news.bbc.co.uk/2/hi/south_asia/4452714.stm, November 19, 2005.
About

Shropshire Conservative (31 August 1844), quoted in William Flavelle Monypenny and George Earle Buckle, The Life of Benjamin Disraeli, Earl of Beaconsfield. Volume I. 1804–1859 (London: John Murray, 1929), p. 629.
1840s

1860s, Allow the humblest man an equal chance (1860)

Canto 5, "Byckerment"
Phantasmagoria (1869)

Source: 1910s, Introduction to Mathematical Philosophy (1919), Ch. 16: Descriptions

The Psychology of the Unconscious (1943)

“I am neither bound to say why I came to this city nor to answer the other questions put to me.”
Quote from a report of the municipal of Toledo, c. September 1579; as cited by Albert F. Calvert, and Catherine Gasquoine-Hartley in: The Spanish Series - El Greco; an account of his life and works; publisher, London: J. Lane; New York: J. Lane Co, 1909, p. 76
this answer El Greco gave to the Mayor of Toledo, when asked - in connection with the writ served on him for the commissioned painting 'The Disrobing of Christ / The Expolio' - whether he had been brought to Toledo to paint the retablo of Santo Domingo (containing 15 paintings of El Greco https://en.wikipedia.org/wiki/El_Greco#/media/File:Domenikos_Theotok%C3%B3poulos,_called_El_Greco_-_The_Assumption_of_the_Virgin_-_Google_Art_Project.jpg)

“To what extent can truth endure incorporation? That is the question; that is the experiment.”
Sec. 110
The Gay Science (1882)

Zadeh (1994) in: Betty Blair. "Short Biographical Sketch" http://www.azer.com/aiweb/categories/magazine/24_folder/24_articles/24_zadeh.html. Azerbaijan International, Vol. 2:4 (Winter 1994), p. 49.
1990s

Ian Smith, as quoted in Heidi Holland, Dinner with Mugabe, Penguin Books; Reprint edition (5 Feb 2009), ISBN 0143026186.

Preface (1957)
1920s, Why I Am Not a Christian (1927)

Addressing the House of Commons after the assassination of Abraham Lincoln (1 May 1865)
1860s

Online http://classics.mit.edu/Plato/seventh_letter.html
The 7th Epistle
Herman Daly in: " Herman Daly http://www.utne.com/politics/herman-daly-economics-cooperative-collective-good.aspx," in Utne Reader,Jan.-Feb. 1995.

Talk titled "Language & Mind", 1997.
Quotes 1990s, 1995-1999

Callum Coats: Water Wizard
Viktor Schauberger: Our Senseless Toil (1934)
The very search for the improvement of the body (and the concomitant “happiness” of the psyche) must lead to further discontent.
page 39.
Creating Beauty to Cure the Soul (1998)

Twain, Mark - Christian Science: Book I. Chapter V http://www.classicreader.com/book/1286/6/

Religion and Science (1935), Ch. IX: Science of Ethics.
1930s
Variant: "What science cannot tell us, mankind cannot know." (Attributed to Russell in Ted Peters' Cosmos As Creation: Theology and Science in Consonance [1989], p. 14, with a note that it was "told [to] a BBC audience [earlier this century]").

Other