Strong and Weak Arguments

[Alex K]

Among the weakest for: Theodicy, that may cast doubt that there is a loving God, but doesn't really make a case for atheism

Strongest against: Fine tuning, contrary to what some deniers say, several physical constants and combinations thereof cannot be changed by more than a tiny fraction without wreaking havoc on our universe's ability to support life.

Would it not make sense to alter more than one constant.
They don't exist in isolation and to alter one would have an effect on the others surely.

Whether the physical constants exist in isolation or are independent is a subtle question. I also think it is two slightly different questions whether they are physically linked in their values by a unified theory, and whether it makes sense to vary them independently in the context of a fine tuning argument. If, say, it turned out that there is an underlying unified physics theory at work in nature (*) without free parameters and which can only result in the physical constants we observe, you can still ask, "why is nature such that the unified physics results in parameters which are exactly right to support complex life, and if I deviate only slightly from the ratios imposed by the unified theory, it doesn't any more". In other words, I think we are allowed to vary physical parameters independently for the sake of a philosophical fine tuning argument even if they are linked physically by a unified theory.

Assuming there isn't an underlying unified theory with no free parameters, many of the parameters we observe are connected by predictions of the standard model of particle physics. E.g.you have 100something chemical elements, but only 24 free parameters in the standard model or so, so obviously when only taking into account the standard model, these 100something atomic masses cannot possibly be varied independently in the context of the theory.

(*) I knowingly neglect the philosophical distinction between what is actually in nature, and our theoretical description thereof, because otherwise I'd never finish. But I assume that we rely on our best theories to talk about nature.