I had a friend years ago who spent some time working with him and he claimed that Sagan's personal belief and knowledge was different from what he portrayed publicly because he was funded heavily by acedemia...that's the case for many scientists. That is Universities and private/government research groups etc. Since his views were widely accepted by the public, he had to be damn careful what he said or he could lose his funding by losing his credibility. To be on the safe side he took the firm stance of "extraordinary claims require extraordinary proof".
Some have claimed over the years that this made him a paid disinformationist. Not at all true. He was a scientist trying to earn a living and had to protect his income.
By saying "extraordinary claims require extraordinary proof", he was indirectly inferring ...."go get the proof, it's out there somewhere".
His great novel "Contact" details a scenerio in which we make contact via interdimensional means. Although it was published as fiction, it wasn't far off from Sagan's beliefs.
Edited by 747400, 13 October 2012 - 07:22 PM.