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So the fine tuning argument has been used to argue for theism, or the multiverse. The argument as I understand it goes something like this:

  1. We live in a universe with life.

  2. The physical constants of the universe if even slightly different would give us a universe without life.

  3. The existing configuration of constants is extremely improbable.

  4. Universe is designed, or we live in a multiverse (where all configurations of constants are manifested in different universes).

An objection to this argument that comes to mind is with regards to 3. I see no reason to believe any other configuration of constants is possible. So there's an "illusion" of a space of possibilities where the laws of physics have the same equations but the constants can take on varying values. But we have no reason to think such a space of possibilities exists. We only knowledge of one universe with these specific numerical values for the constants. The probability of this configuration of constants may very well be 1. There's no way to know. So the question really boils down to, "why is the universe the way it is?".

What are the responses to this objection?

EDIT: Here's a video from a physicist that illustrates this objection:

https://www.youtube.com/watch?v=c6DP5lgzmTA

Ameet Sharma
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    Many physicists working on theories that try to "unify" the fundamental forces of physics think there will turn out to be multiple possible low-energy vacuum states with different values of various "constants", and where the vacuum was originally in a more symmetrical but unstable high-energy state (where all particles were massless, for example) and then dropped randomly to one of the low-energy 'metastable' states by [spontaneous symmetry breaking](http://hyperphysics.phy-astr.gsu.edu/hbase/Forces/unify.html). See quotes I posted [here](https://philosophy.stackexchange.com/a/70921/10780). – Hypnosifl Apr 26 '21 at 16:36
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    If this is true, then in [eternal inflation](https://cds.cern.ch/record/485381/files/0101507.pdf) models a natural consequence is that different regions far apart can drop randomly to different low-energy vacuum states with different constants. However, if you want to know more about arguments for why physicists think some constants of nature were determined by spontaneous symmetry breaking, and the arguments for eternal inflation models with different "bubble universes" that have settled to different vacuum states, this would be a question for https://physics.stackexchange.com/questions – Hypnosifl Apr 26 '21 at 16:39
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    We have methodological reasons to reject skeptical non-explanations like "there's no way to know" when an alternative is available. Other things being equal, a theory that provides a background to what we observe is preferable to a "theory" that it just happens this way. We have science because we generally prefer potential explanations to skepticism. – Conifold Apr 26 '21 at 17:41
  • @Conifold, what alternative? Are you talking about inflation theory? – Ameet Sharma Apr 26 '21 at 18:51
  • So here's a physicist making the same argument: https://www.youtube.com/watch?v=c6DP5lgzmTA Is she missing some evidence regarding an empirically supported probability distribution? – Ameet Sharma Apr 26 '21 at 19:34
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    The goal of unifying the strong, electromagnetic, and weak forces into a [Grand Unified Theory](https://en.wikipedia.org/wiki/Grand_Unified_Theory) with strong empirical support, let alone unifying all three with gravity into a [Theory of Everything](https://en.wikipedia.org/wiki/Theory_of_everything), has not been accomplished yet, so it's true there's no agreed-upon and empirically supported probability distribution. But most physicists think there are good reasons to believe such a theory is out there waiting to be found, and that it will likely feature spontaneous symmetry breaking. – Hypnosifl Apr 26 '21 at 20:32
  • Intelligent design and multiverse are non-skeptical alternatives. They may not be great, but still preferable to skepticism if nothing else is available and if there are no compelling independent reasons to reject them. – Conifold Apr 26 '21 at 20:41
  • If the physical constants of the universe were slightly different, that would not give "us" a universe without life, because if there's no life, there's no "us." – Sandejo Apr 26 '21 at 21:06
  • @Conifold, I don't see how either possibility functions as an explanation. Intelligent design merely postulates another being instead of the universe itself that now requires explanation just as the universe itself did. Multiverse doesn't explain anything either. We have a contingent fact about our current experience. We can't accept the contingency so we propose that all possibilities happen. But we're still faced with the contingent fact that we're having this experience right now when something else was possible. In either case, we are left with an equal need for further explanation. – Ameet Sharma Apr 26 '21 at 21:26
  • Any explanation postulates something else in need of further explanation, but an extra link in the chain is progress, it is better than acquiescing to a dead end. For example, postulating action at a distance for gravity raised questions about action at a distance. And placing a contingency into an array of contingencies removes the need to explain them one by one, we do not wonder why this or that species happened to evolve, only what mechanism can generally produce them. Ultimately, what people find explanatory is a matter of judgment, and enough people find ID and multiverse explanatory. – Conifold Apr 26 '21 at 21:42
  • "Any explanation postulates something else in need of further explanation, but an extra link in the chain is progress"... ID is just one explanation from a very specific cultural context (judeo-christian). There's a myriad of other creation myths. https://en.wikipedia.org/wiki/List_of_creation_myths eg world turtle. Without the boundaries of falsifiability, I don't see how simply positing one of these myths as an explanation is progress. I could create a new myth. – Ameet Sharma Apr 26 '21 at 23:19
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    The ID does not have to be God, simulation speculations are very popular these days and they are from a different context. Both ID and random generation are generic potential explanations for coincidences of any sort. They are neither myths nor completed theories, they are templates for more specific hypotheses that point to further exploration. Neither simulation nor multiverse are treated as more than that, and are better methodologically than a pessimistic discussion stopper like "there's no way to know". – Conifold Apr 27 '21 at 00:20

2 Answers2

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The simplest argument is (simply) that if the constants of nature were slightly different, we wouldn't be here to register that fact. So however improbable our universe may be, we are nonetheless and indeed here.

Regarding your assertions "I see no reason to believe any other configuration of constants is possible" and "but we have no reason to think such a space of possibilities exists": have you looked for a reason, who is "we", and are you trained as an astrophysicist?

In the field of cosmology, discussions like these arise in the context of the anthropic argument, about which lots has been written. I suggest you do a search on the physics stack exchange and possibly post your question there.

niels nielsen
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Your wish that there were no evidence to support the unlikelihood of the universe is unjustified wishful thinking.

The values of the constants of the universe, things like the Baryon number, and the relative strengths of the various forces, are not set by any physics-based constraints we know of in the Standard Model. Instead, we actually have good reason to think they change. The basic idea of the Big Bang Inflation theory is that our Cosmological Constant was very very high for a brief time, then dropped to something close to zero. We also think it may be growing slightly. In the Standard Model, a CC only changes when other constants change -- so we have good reason to think that these parameters are variable.

Additionally, all our "laws" appear to be mere regularities -- physicists believe that every one of them spontaneously breaks (IE fundamental properties reset), per gauge symmetry theory. https://www.pnas.org/content/93/25/14256

For a philosophic discussion of symmetry theory see: https://plato.stanford.edu/entries/symmetry-breaking/

The view that our universe is astonishingly unlikely per our current laws of physics is widely accepted among physicists. That is why multiverse speculations are so widely held among the non-theist physicists.

Dcleve
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    Is there evidence that these constants change? – Ameet Sharma Apr 26 '21 at 19:09
  • So I've posted this video in my original post from a physicst: https://www.youtube.com/watch?v=c6DP5lgzmTA She basically says there's no empirically supported probability distribution. Is she missing some evidence to the contrary? – Ameet Sharma Apr 26 '21 at 19:32
  • You Tube videos, and videos in general, are not good references for anything other than being told something, they lack the content and evidence needed to support a claim. Your citing one physicist posting a video - is a classic case of cherry picking data to provide confirmation bias, and doing so using weak/invalid references. Your speaker makes false claims about science -- she does not understand the scientific process. Multiple tests are not needed to "establish a probability distribution". Science is not based on replication, but on hypothesis and test. – Dcleve Apr 27 '21 at 06:56
  • As noted in the link I provided, there is observation that most constants spontaneously break symmetry, and well supported theory that they all will. Your video is in denial of this well established physics. Your speaker also rejects the central premise of science, which is to ask "and why is THIS the case". She also misrepresents the central premise of the FTA, which does not rely upon "probability distributions" but on "possible ranges". The ranges that the constants in physics could take, are massive. And the ranges that life is possible, are tiny. For each of 30 constants. – Dcleve Apr 27 '21 at 07:05
  • (1-Range-life/Possible-range) is likelihood of a no-life universe, with no assumed distro, for one constant. Multiplied together, you get an astronomically high likelihood of no life. I note she did not present this very basic feature of the FTA, because it would make her whole video clearly a piece of delusional propaganda. She also mis-represented "other complex chemistry is possible" as if it were relevant. the no-live universes are all vaccuum, or all black holes, or collapse to nothing in the first 20 nanoseconds, etc. Other chemistry, is a trivial tiny subset of that range. – Dcleve Apr 27 '21 at 07:11