Every so often I get an e-mail out of the blue about two sentences in a story published in The Post in 1996. I quoted Carl Sagan: “An atheist has to know a lot more than I know. An atheist is someone who knows there is no God.”

People who contact me want to know where the quote came from. Answer: He said it to me in an interview. (I might even have it on tape somewhere in the bottom of a file box). He said identical, or similar things, many times. You can find such material in his voluminous papers now archived at the Library of Congress. For example:

To Robert Pope, of Windsor, Ontario, Oct. 2, 1996

“I am not an atheist. An atheist is someone who has compelling evidence that there is no Judeo-Christian-Islamic God. I am not that wise, but neither do I consider there to be anything approaching adequate evidence for such a god. Why are you in such a hurry to make up your mind? Why not simply wait until there is compelling evidence?” [It’s a bit puzzling that Sagan specifies the Abrahamic faiths in his definition of an atheist.]

To Stephen Jay Gould, Dec. 18, 1989, after a newspaper editorial referred to Sagan and Gould as “dogmatic” on the question of whether there is a God:

“Do you understand how – assuming either of us ever did say ‘The universe can be explained without postulating God’ – this could be understood as dogmatic? I often talk about the ‘God hypothesis’ as something I’d be fully willing to accept if there were compelling evidence; unfortunately, there is nothing approaching compelling evidence. That attitude, it seems to me, is undogmatic.”

Does this wait-and-see attitude make Sagan an “agnostic”? That word seems inadequate to me. Yes, he held out the possibility of a God, but believed that possibility to be very small. His position was the strictly scientific one: Knowledge is always provisional and contingent upon further data.

David Grinspoon, a planetary scientist whose father was Sagan’s best friend, and who referred to Sagan as “Uncle Carl,” tells me by e-mail:

“In his adult life he was very close to being an atheist. I personally had several conversations with him about religion, belief, god, and yes I agree he was darn close. It’s really semantics at this level of distinction. He was certainly not a theist. And I suppose I can relate because I personally don’t call myself an atheist, although if you probed what I believe, it would be indistinguishable from many who do use that term.”

David Morrison, one of Sagan’s students back in the day, tells me by e-mail, “Carl acted like an atheist but rejected the label. I guess it seemed too absolute to him. He always tried to be open to new evidence on any subject. I am reminded of Bill Nye answering a question about what could change his mind about evolution : ‘evidence’.”

I e-mailed the person who would know Sagan’s views better than anyone: Ann Druyan, Sagan’s widow. I specifically asked her about the quote in my 1996 story (“An atheist has to know a lot more than I know. An atheist is someone who knows there is no God”). Druyan responded:

“Carl meant exactly what he said. He used words with great care.He did not know if there was a god. It is my understanding that to be an atheist is to take the position that it is known that there is no god or equivalent. Carl was comfortable with the label ‘agnostic’ but not ‘atheist.'”

Here’s a definition of “agnosticism” from Merriam-Webster: “Agnosticism may mean no more than the suspension of judgment on ultimate questions because of insufficient evidence, or it may constitute a rejection of traditional Christian tenets.” The same online dictionary says of “atheism,” “Unlike agnosticism, which leaves open the question of whether there is a God, atheism is a positive denial.”

By these definitions, we should call Sagan an agnostic. And yet … to my ear, “agnostic” doesn’t quite capture the skepticism that Sagan brought to the issue. I want a word with a little more spin on it.

Surf around the Web and you’ll find other parsings of “atheist” and “agnostic,” including one at about.com that talks about the concept of an “agnostic atheist.” You might also want to check out the commentary Penn Jillette did for the NPR “This I Believe” series, in which he begins, “I believe there is no God” (he describes that as “beyond atheism”).

(Another question is whether Sagan was “scientistic,” something that I’ll discuss in a future blog post, which is why I headlined this Part 1.)

As a high-profile non-believer, Sagan received a lot of mail from religious people and from fans of his work who wanted to engage on theological issues. In the Sagan papers at the Library of Congress one comes across much correspondence in the last year of his life that touches on issues of life after death, God, Heaven, prophecy, and so on. Sagan wasn’t about to ease up on his skepticism about the possibility of an afterlife.

In April 1996, less than a year before his death, he wrote to a certain Father Martin:

“Thanks for your kind invitation. The question ‘How can I find God?’ assumes the answer to the key undecided issue. I’m sorry I won’t be able to participate. With best wishes…”

Late that year, he had a pointed exchange with the noted skeptic Martin Gardner, and I discussed that in the Sagan profile published earlier this year in Smithsonian magazine.

Sagan became agitated after reading a new book by the legendary skeptic Martin Gardner, whom Sagan had admired since the early 1950s. It suggested that perhaps there was a singular God ruling the universe and some potential for life after death. In November 1996, Sagan wrote to Gardner: “[T]he only reason for this position that I can find is that it feels good….How could you of all people advocate a position because it’s emotionally satisfying, rather than demand rigorous standards of evidence even if they lead to a position that is emotionally distasteful?”Gardner responded: “I not only think there are no proofs of God or an afterlife, I think you have all the best arguments. Indeed, I’ve never read anything in any of your books with which I would disagree. Where we differ is over whether the leap of faith can be justified in spite of a total lack of evidence…”

He was determined not to believe in something just because — particularly with his grave illness — it would be reassuring. There was great intellectual courage in that.

Sagan knew, though, that rigid skepticism would not help the enterprise of science. In “The Demon-Haunted World,” he wrote (h/t Jennifer Ouellette’s blog):

“If you’re only skeptical, then no new ideas make it through to you. You never learn anything. You become a crotchety misanthrope convinced that nonsense is ruling the world. (There is, of course, much data to support you.) Since major discoveries at the borderlines of science are rare, experiences will tend to confirm your grumpiness. But every now and then a new idea turns out to be on the mark, valid and wonderful. If you’re too resolutely and uncompromisingly skeptical, you’re going to miss (or resent) the transforming discoveries in science, and either way, you will be obstructing understanding and progress. Mere skepticism is not enough.”

I asked our ace religion reporter, Michelle Boorstein, to offer thoughts on Sagan’s beliefs, and she obliged: