My Week Without Cosmic Hope

(Photo by Tom Pumford on Unsplash)

For the past few years, I’ve believed that there is a purpose to the universe, on the basis of the fine-tuning of physics for life and psycho-physical harmony. Belief in cosmic purpose leaves a lot uncertain. I don’t believe in an all-powerful deity who can ensure a happy ending, and it could be that we’ve reached the climax of cosmic purpose already. But I’ve come to think a certain slightly heretical interpretation of Christianity, close in spirit to what the Eastern Orthodox church believes, is probable enough to put my faith in.

It’s nice living in hope of a greater purpose. It’s quietened my ego, making me less bothered about personal success and failure, and freed me up to be more fully emersed in the joy of the present moment. However, I’m also fundamentally driven by the truth, and everyday there is a monologue in my head pressing on me the strongest objections I can find to my position. I’d give it up in a flash if I changed my mind on where the evidence is pointing.

And last week I did. Well, not quite, but I significantly lowered my credence in cosmic purpose. There is one individual to blame for this: my good friend/philosophy frenemy Mark O’Brien (‘disagreeableme’ on X and Bluesky). As well as the monologue in my own head, I get regular powerful challenges from Mark, either on WhatsApp or in the pub when we get a chance to get together in person. And after a day or so of reflecting on our pub conversation 7th December, I decided Mark was right after all that the multiverse can explain fine-tuning.

Our arguments are often a bit technical — especially given we’ve been discussing this for a good few years now, and so getting more and more into the weeds. I’ll give the gist of our dispute at the end of this post.

Just because the multiverse can explain fine-tuning, that doesn’t mean cosmic purpose cannot also explain fine-tuning. Of course all the atheists who take fine-tuning seriously go for multiverse, and all the theists go for God. But if both explanations can in principle do the job, then everyone should give non-negligible credence to each possibility. And if you think one side is the better explanation, then your view had better be based in some serious argument, rather than just offering cultural biases in support of your preferred option.

However, whichever ends up being the better explanation, it’s clear that the probability of cosmic purpose is significantly less if the multiverse is in the picture than it is if cosmic purpose is the only explanation of fine-tuning. And so I spent the whole of last week with a much lower credence in cosmic purpose.

Having a lower credence in cosmic purpose didn’t undermine my faith, as I think faith is about trust rather than belief or certainty, and thus only requires that the object of faith is a credible possibility (around 30%). Also, I’d be quite happy to go back to being a religious fictionalist, which I was for many years, if I became an atheist again. But I can’t deny it made me feel a little bit sad that there’s less hope of cosmic purpose than I’d previously thought. You owe me a drink Mark! 🤣

In any case, a week later on Saturday 14th, I decided (whilst driving to my elder daughter’s 8th birthday party) that actually there are big problems with Mark’s position (again I’ll explain briefly below), and after another day or so of reflecting, I’ve once again come to the conclusion that the multiverse is not an option for dealing with fine-tuning. Hooray, cosmic purpose is back in business!

Some may say my reversion to my old view involved motivated reasoning. That’s always a risk, and a danger both sides of this debate should take seriously. But I am genuinely driven to find the truth on these matters, and so I’m reasonably confident that’s not what I’m doing.

It’s been a really intellectually stimulating week for this reason (among others). And one outcome is that I’ve designed in my head a new paper exploring which explanation of fine-tuning would be better, if both cosmic purpose and the multiverse are on the table. This is handy, as I’m massively overdue for a paper for a volume on theism versus atheism edited by Andrew Drinkard. It’s a bit awkward, as I was invited to be on the atheist side before my conversion to heretical Christianity. But hopefully this paper will do that job I was invited to do, because I’m inclined to think that if the multiverse is in play, then it’s a better explanation of fine-tuning, especially if the alternative is an all-powerful God.

For more on the fine-tuning argument for cosmic purpose, see this recent debate with me, Rowan Williams, Liz Oldfield and Alex O’Connor, or for more on why multiverse can’t explain fine-tuning, see this recent article of mine for IAI.

In the meantime, whether you believe in cosmic purpose or not, whether you’re celebrating Christmas or not, I wish you all a very happy holiday!

The Techy Details

Mark an I both agree that this paper demonstrates that whether or not the multiverse can deal with fine-tuning depends on whether we should put the fact that our universe exists into the “background information” when reasoning about fine-tuning. Whenever you do probabilistic reasoning, you put in the “background information” certain facts you’re taking for granted. The paper linked to above shows that if you put in the background the information that our universe exists, then the fine-tuning data doesn’t provide evidential support for a multiverse. If you’re interested in seeing why but don’t have time to read the paper, check out my brief talk 4 hours 5 mins into day 2 of this conference.

I’ve always been on the side that thinks you should put the existence of our universe into the background information, as the evidence we’re considering is that our universe has the right numbers for life rather than its existence. But Mark persuaded me that night that we shouldn’t put it in, on the grounds that our knowledge that the universe exists depends on the universe having the right numbers for life. What really drove the point home was comparisons to other cases where it’s clear we would do what Mark thinks we should do in the case of fine-tuning, such as the case of Fred the uranium atom in the paper linked to above.

The gist of my worry a week later with Mark’s position is realising you’re not going to be able to put anything in the background information if you’re considering the evidence that our universe has the right numbers for life, as all your knowledge is dependent on our universe having the conditions that allow you to exist (I also worry Mark won’t be able to put anything in the background if he’s considering the evidence that his parents got together, for the same reason). And I think this is really important, as we need stuff in the background to constrain the set of possibilities we’re dealing with. You can’t just ask: From all the possible worlds that might have existed, what percentage are compatible with life?

I’ll offer Mark the chance to reply to this on this post.