They were (or are - if still alive) respected cosmologists.
They had the strong anthropic principle - the universe exists because we see it and...
...the weak anthropic principle - we see the universe with its critical fundamental constants because the universe exists in a form that produces beings that can perceive it.
I'm kind of a credulous guy; I am uncritical of what is new to me until at least it's old to me, whereupon I feel free to reject it if warranted by my opinions. I certainly went through that with Frank and John. Their book "The Anthropic Cosmological Principle" is still on my shelf, remembered as something of a fun read, but frankly quite dusty and unopened for decades.
I think Frank had a follow up. Someone gave it to me, or maybe it was a Christmas or Birthday present. If I recall, I may have opened it and found it a little woo woo for my tastes, which is not to say that Frank and John are not smart guys but...
It smacked at the end of the day, for me at least, of religious philosophy or quasi religious, in that it is not subject to experimental verification. There is no way to study a universe with different fundamental constants.
(Freeman Dyson showed by studying a samarium isotope - I think it was samarium - that the fine structure constant has been constant for billions of years. I actually had in a wonderful afternoon, the opportunity to chat with him about it.)
I'm an atheist facing the end of his life; that we exist, that I exist, that the universe exists, strikes me as remarkable but wholly ineffable. I need no "why," only "is." It's a beautiful thing to have existed, or is and was in my case if not in every case, but I simply must accept that it seems to have occurred for reasons not subject to proof, and I'm sure it will go on.
No solipsism for me. If that's something like "faith," that it will go on, so be it.
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