There is a scene in one of my favorite movies "Contact" where Jodie Foster discusses Occam's Razor with Matt McConnoughy's religionist character. The context is, a discussion over 'The Creator' and 'Ellie' requiring proof.
That part of the movie was always a little unsatisfying. I could never accept that her character would walk headfirst into a loaded debate. I also didn't see where the argument "Did you love your father? Yes. Prove it." applied to anything; the muddy implication was that her love for her father was not 'real' since she could not 'prove it.' As a scientist, she claimed she needed 'proof' for a concept that, by its very definition, is unilaterally impervious to proof offered by others; an entity that exists outside of the Univers we find ourselves in. I can accept that some love the concept of God. Love is a concept that easily permits that. It's not proof of that love that is in question or even questionable; the heart loves what the heart loves. But he didn't ask 'prove that your father existed.' There could be all forms and manner of acceptable proof for that. The argument was a little too clever by half. As usual, a deflection of the issue at hand. Does God exist?
If we will be, then we will be in some Universe; we may endlessly redefine our understanding of that Universe/megaverse or whatever, but at every point of our understanding, by definition, the concept 'God' is forever outside. It isn't hard at all to imagine Mankind's ability to dream up both real and imaginary singularities(no mathematical pun intended, or maybe so); we do that all the time. 1/0 The truly amazing aspect of religion is that so much of Mankind falls for the act of other peers jarringly speaking for that which they claim is unimpeachably forever outside the Universe we are in. A curiously mute God that requires huckster naked sweaty ape politicos to speak for it and amplify its messages, or perhaps, deliver them to us because that God doesn't know our address and needs help.
Or, maybe that concept is being abused politically by peers sharing this reality with us; and my choice between those two possibilities is for sure easily guided by the principle of Occam's Razor.
Foster's character -- Ellie Arroway, the quintessential Jody Foster character -- gets screwed along the way by religionists(and one charlatain in particular, her kind of boss, the Tom Skerrit character). Sagan was clearly intrigued -- as a scientist -- with this qustion of religion. One of the best parts of the book was left out of the film; Sagan examined the question, 'OK-- what might an objective, scientific evidence of a Creator look like?' In the book, that question was examined by -imagining- researchers looking for -- and finding -- a 'message in Pi' . The 'message' that was found was graphical; when run out to some massive number of significant digits in some base other than 10, the digits, when placed into a frame of some dimension, displayed a (rasterized) 'perfect circle' with a cross in the center. (Never mind, this depends on pixel aspect ratio. Lets assume 1:1, a not important detail.) An unlikely message, buried inside of a physical constant, waiting to be found. Would that be proof? That is the question I think he was examining with that. Because ... would it be proof? It would certainly be evidence-- evidence that would be hard to explain as mere chance. "Hidden within Pi is an image of the meaning of the constant Pi."
And pure fantasy, because such evidence has not been found. But not the point of his examining that question. But in that hypothetical, how would Occam's Razor come down?
It was a significant aspect of the book. I can see why it didn't make it into the film. It kind of got glossed into Arroway's bewilderment over what she experienced. What I took away from the ending of that film and reading the book was the sense of a scientist looking at the Universe as it is and realizing it is miracle enough. Some have argued that Arroway's character had a kind of spiritual transformational religious epipheny because of her witnessing 'a celestial cosmic event' and her description of 'being a part of something much bigger than ourselves' , but I didn't see that as anything other than a realization that she learned, in the context of this story and her experience, that we are not alone in the Universe, that it is teaming with life. I thought that was pretty specific in both the book and the story and is entirely consistant with Sagan's other discussions about the probability -- no, liklihood-- that there is not only life elsewhere in the Universe, but lots of it. Sagan, I think it safe to say, was enthralled with that question: are we alone? It's clear to me he believed 'not.'
I think Occam's Razor also falls down on Sagan's side of that assessment.