Category Archives: Stephen Hawking

The Greatest Obstacle to Discovery Is Not Ignorance—It Is the Illusion of Knowledge

Daniel J. Boorstin? Stephen Hawking? Henry Thomas Buckle? Anonymous?

boostin11Dear Quote Investigator: Widely accepted false beliefs can hinder progress and new discoveries. For example, the mistaken belief that heavier-than-air flying machines were impossible or impractical deterred requisite financing and investigation. This thought has been expressed as follows:

The greatest enemy of knowledge is not ignorance; it is the illusion of knowledge.

The famous physicist Stephen Hawking and the Librarian of the U.S. Congress Daniel J. Boorstin have both been credited with this statement, but I am having trouble finding good citations. Would you please help?

Quote Investigator: This saying was attributed to Stephen Hawking by 2001, but QI has been unable to find substantive evidence that he actually employed it.

The best-selling author, educator, and librarian Daniel J. Boorstin was interviewed in “The Washington Post” in January 1984. He modestly referred to himself as an amateur historian because his primary background was the legal profession. Boldface has been added to excerpts: 1

What an amateur is, is a lover of a subject. I’m a lover of facts. The fact is the savior, as long as you don’t jam it into some preconceived pattern. The greatest obstacle to discovery is not ignorance—it is the illusion of knowledge.

Boorstin employed different versions of the saying over the years, but he did not assert that the underlying idea was his own. Indeed, he once ascribed a similar notion to the well-known historian Edward Gibbon, and on another occasion, he called it an aphorism. Detailed citations are given further below.

Here are additional selected citations in chronological order.

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  1. 1984 January 29, The Washington Post, The 6 O’Clock Scholar: Librarian of Congress Daniel Boorstin And His Love Affair With Books by Carol Krucoff, Start Page K1, Quote Page K8, Column 2, Washington, D.C. (ProQuest)

The Best Evidence That Time Travel Is Not Possible Is That We Have Not Been Invaded By Hordes of Tourists from the Future

Stephen Hawking? Apocryphal?


Quote Investigator: There is an argument against the existence of time travel that can be stated as follows:

If time travel were possible, we would have been overrun by tourists from the future by now.

Did the famous physicist Stephen Hawking say something like this? Alternatively, was it said by another physicist or a science fiction writer?

Quote Investigator: In January 1991 Stephen Hawking delivered a lecture at Cambridge University during which he expressed skepticism about the possibility of traveling backward in time: 1

But the best evidence we have that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future.

This quotation appeared in the chapter titled “The Future of the Universe” in the collection “Black Holes and Baby Universes and Other Essays” by Hawking, and the date of the speech was specified in a footnote.

Here are additional selected citations in chronological order.

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  1. 1993, Black Holes and Baby Universes and Other Essays by Stephen Hawking, Essay: 13: The Future of the Universe, (Asterisk footnote: “Darwin lecture given at the University of Cambridge in January 1991.”), Start page 141, Quote Page 154, Bantam Books, New York. (Verified with scans)