Here are a few basic objections to fine tuning.
1 The claim that atheism can’t explain fine tuning is just nonsense. If we live in a multiverse—which is the most popular view in physics because it explains other phenomena, have a universe that repeats with different laws of physics, have a sufficiently large universe, have some law that requires complex structures emerging, have an evolving universe produced by black holes creating new universes, or dozens of other options, these would also explain fine tuning. These all establish mechanisms for lots of iterations of the universe—some of which will be finely tuned for life. If physicists already believe in a multiverse, it makes no sense to add God to the picture.
2 We can’t know the universe is finely tuned—other life could arise under different laws of physics. We have quite literally no idea under what conditions life can arise. We don’t know what 95% of the universe is made of—dark energy and dark matter—so it’s very premature to say life can’t arise under different conditions. Adams in a 2019 literature review argues that a wide range of possible laws of physics could result in life—the universe just isn’t finely tuned. In fact, Adams argues that there are lots of other parameter values for the laws of physics that would result in way more life. To quote the Stanford encyclopedia of philosophy “If Adams is right, our universe may just be garden-variety habitable rather than maximally life-supporting.” Stenger wrote a computer program that allows anyone to simulate different values of physics and concluded that randomly plucking universe parameters from thin air can still produce universes quite capable of harboring life.
Additionally, there could be totally different laws regarding consciousness, leading to electrons, planets, or any other structure being conscious, meaning that there’s no reason to think that only this configuration of entities could result in conscious beings,
3 The universe could be finely tuned by an apathetic deity, a trickster being, a cohort of fairies, or even an evil deity. There’s no reason it has to be finely tuned by a good being.
4 God is a very complex system that would thus require find tuning. I see no reason to think that a universe existing with a complex assembly of laws resulting in life would be any less likely than a finely tuned God with infinite knowledge, power, and goodness just existing. Indeed, if disembodied minds like God can just exist that means that fine tuning needs no explanation because there could just be lots of disembodied minds that exist.
5 Theism can’t explain why the universe is not finely tuned enough—most of it is inhospitable. This would be like saying that a house was designed just for me when I can’t fit in anywhere but a tiny closet—the rest of the house only designed for mice to fit.
6 Why does God need to make a finely tuned universe? Making a strange universe with finely tuned parameter values for laws of physics that take billions of years to produce complex life would not be expected on theism.
7 If God exists the odds that the universe would be finely tuned in exactly the way that it is are very low—theism isn’t a good explanation because it can’t explain why God chose to make the universe with the laws of physics that it has. However, multiverse theories guarantee a universe like ours.
8 To quote Carrier , “The only way we could exist without a God is by an extremely improbable chemical accident, and the only way an extremely improbable chemical accident is likely to occur is in a universe that’s vastly old and vastly large; so atheism predicts a vastly old and large universe; theism does not.”
9 Similarly, to quote Carrier once again “existence without God requires an extremely long process of evolution by natural selection, beginning from a single molecule, through hundreds of millions of years of single cells, through hundreds of millions of years of cooperating cells, to hundreds of millions of years of multicellular organisms; so atheism predicts essentially that; theism does not.”
10 How do we decide the relative probabilities of each possible value for the laws of physics? These numbers are just made up! We don’t know what makes particular laws of physics have values that are more or less likely than other ones. We’ve already seen examples of constants that have been claimed to require fine tuning—like early entropy. As Stenger argues—some key areas of physics – such as the equality of the charges on the electron and proton – are set by conservation laws determined by symmetries in the universe, and so couldn’t be any different. It’s incredibly premature to say that our laws of physics are finely tuned when we don’t have a grand model that even lets us know what the fundamental laws are or how they’re determined. However, it seems like most people disagree with Stenger, but it’s still a viable hypothesis.
11 If you can just make up a philosophical principle to explain fine tuning then so can I. Modal realism says that everything metaphysically possible will actually happen—all possible worlds really exist. There are some other arguments for modal realism—but it seems like this is at least as good an explanation for fine tuning as God.
I agree