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More quotes about uncertainty

Attributed to Justice Oliver Wendell Holmes:

The longing for certainty ... is in every human mind. But certainty is generally illusion. 

From Albert Einstein:

" ... as far as the propositions of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality."
Geometry and Experience, Lecture before the Prussian Academy of Sciences, January 27, 1921

From Philosopher and Logician Bertrand Russell:

When one admits that nothing is certain one must, I think, also add that some things are more nearly certain than others.
    Am I An Atheist Or An Agnostic?, 1947

Attributed to John Henry Cardinal Newman:

If we insist on being as sure as is conceivable... we must be content to creep along the ground, and can never soar.

From Astronomer and Writer Carl Sagan:

    Humans may crave absolute certainty; they may aspire to it; they may pretend ... to have attained it. But the history of science—by far the most successful claim to knowledge accessible to humans—teaches that the most we can hope for is successive improvement in our understanding, learning from our mistakes, an asymptotic approach to the Universe, but with the proviso that absolute certainty will always elude us.
    We will always be mired in error. The most each generation can hope for is to reduce the error bars a little, and to add to the body of data to which error bars apply. The error bar is a pervasive, visible self-assessment of the reliability of our knowledge.
        The Demon-Haunted World: Science as a Candle in the Dark ( 1995), p. 28.

From Physicist and Nobel Laureate Richard Feynman:

    I have approximate answers and possible beliefs in different degrees of certainty about different things, but I'm not absolutely sure of anything.
        Interview in BBC program Horizon, 1981

    The scientist has a lot of experience with ignorance and doubt and uncertainty, and this experience is of very great importance, I think. When a scientist doesn't know the answer to a problem, he is ignorant. When he has a hunch as to what the result is, he is uncertain. And when he is pretty damn sure of what the result is going to be, he is still in some doubt. Scientific knowledge is a body of statements of varying degrees of certainty -- some most unsure, some nearly sure, but none absolutely certain.
        "The Value of Science," address to the National Academy of Sciences (Autumn 1955)

    Some people say, "How can you live without knowing?" I do not know what they mean. I always live without knowing. That is easy. How you get to know is what I want to know.
        The Meaning of it All (1999)

    We absolutely must leave room for doubt or there is no progress and no learning ... People search for certainty. But there is no certainty.
        From the lecture "What is and What Should be the Role of Scientific Culture in Modern Society", given at the Galileo Symposium in Italy, 1964.