I'm just aiming for a general audience in this post, not a philosophically educated one. The philosophically informed and trained would know about the works of philosophers and physicists like Robin Collins, Luke Barnes, etc. I'd heartily recommend following them on fine-tuning.
That said, given the purported evidence for fine-tuning, then the main options seem to be:
- Reject the evidence strongly argues for fine-tuning.
- Accept the evidence strongly argues for fine-tuning, but argue the fine-tuned universe "just is".
- Accept the evidence strongly argues for fine-tuning, but argue the multiverse is behind it all.
- Accept the evidence strongly argues for fine-tuning, but argue for design by an intelligent designer.
I'll quickly run through each of these options:
- The evidence seems to be everywhere. For instance, if I understand him aright, Robin Collins divides the evidence into three broad categories:
a. Evidence for fine-tuning in the laws of nature (e.g. altering ever so minutely any of the fundamental forces, i.e., the law of gravitation, electromagnetism, the strong nuclear force, the weak nuclear force)
b. Evidence for fine-tuning in the constants of nature (e.g. changing the fine-structure constant, which, as Richard Feynman once said: "It's [the fine-structure constant, approximately 1/137] one of the greatest damn mysteries of physics: a magic number that comes to us with no understanding by man. You might say the 'hand of God' wrote that number, and 'we don't know how he pushed his pencil'")
c. Evidence for fine-tuning in the initial conditions of nature (e.g. as Roger Penrose has said: "In order to produce a universe resembling the one in which we live, the Creator would have to aim for an absurdly tiny volume of the phase space of possible universes [i.e. one part in 1010123]").
For many other examples, see a book like Just Six Numbers by Martin Rees.
(And, of course, I'm leaving aside the biological and chemical arguments for now.)
- If we argue the finely-tuned universe is a brute fact, that the finely-tuned universe "just is," that we humans just happened to exist in such a finely-tuned universe by chance, that seems highly improbable, to put it mildly!
Philosopher-physicist Robin Collins calls it the "surprise" factor. Suppose we are astronauts traveling to a distant and otherwise deserted planet. Suppose we come across a strange monolith which when approached is suddenly activated, and tells us: "Welcome to our planet, intergalactic voyagers from Earth!" It would seem highly implausible if we therefore concluded this monolith just happened to be here by random chance.
- This only pushes the question back a step because we would need to explain the fine-tuning of the multiverse itself. In which case some might argue the multiverse itself is a brute fact. If so, then it'd bring us back to (b).
- Seems far more reasonable than the other choices to me.
Many atheists would even agree. For example, they'd argue our universe is a computer simulation in a universe which contains our own. Perhaps like in "The Ricks Must Be Crazy" in Rick & Morty. But how likely is this? What are the arguments and evidences for the simulation hypothesis? Perhaps I'll explore this in a future post.
However, my own position is Christian theism. That's the most probable and reasonable one in my mind. (Although to be fair my belief in Christianit is not only due to arguments from design including fine-tuning, but many other arguments as well.)
All in all, this video sums it up much better than I can: