Why is the universe life-permitting?
The universe has the conditions life needs. Why do those conditions work out?
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Consider how the universe and living things are ordered, and whether intelligence best explains them.
We have seen why order in nature can point to design. Now look at something more specific: the conditions that make life possible anywhere in the universe.
The stars overhead
The next walk runs later than usual. As you turn back through the park, the first stars are coming out. Jordan looks up. “Last time you said we needed something more specific than ‘nature looks designed.’ Is this where you're going?”
You point toward the stars. Before any planet could support life, you tell him, the universe needed conditions that allow stars, atoms, and complex chemistry in the first place.
“But isn't that just because we're here?” Jordan asks. “If those conditions were different, there wouldn't be anybody around to complain.”
“That explains why we can notice the conditions,” you say. “Does it explain why they're there?” Jordan looks back up. “All right. Show me what's so unusual about them, and then tell me why you think God explains it.”
The universe has the conditions life needs, even though many other settings would make life impossible. A Creator who intended life to exist would have a reason to make the universe this way.
The design argument gets more specific here. We can look at the physical conditions that make life possible anywhere in the universe and ask why they are there.
Why do the conditions for life point toward a Designer?
Before any planet could support life, the universe needed stable atoms, stars that last, and the right conditions for complex chemistry. Those things depend on basic settings in physics. Change some of the values, and life would not be possible. Scientists call this fine-tuning.
One example is the cosmological constant, a number connected to how the universe expands. If it were much larger and positive, matter would spread out too quickly for galaxies to form, assuming the other conditions stayed the same. Other settings affect whether stars can last and produce the elements life needs.
Physicists study what would happen if these values were different. Across many of the ranges they examine, only a small fraction of the combinations could support life. Most of the settings considered in those models would prevent lasting stars, stable atoms, or complex chemistry. That doesn't tell us the exact odds of an undesigned universe, because we don't know how likely the different settings are. Our universe has the conditions needed for all three.
This is where design comes in. If a mind intended life to exist, then a universe with the conditions life needs is exactly the kind of result we have a reason to expect. The question is why our universe has those conditions in the first place.
If this is the only universe, how did those conditions end up working together so well? Some argue that the values were unavoidable, although no established theory shows that every important setting had to allow life. Others call it luck. That still leaves us asking how the universe got those settings in the first place.
The explanation would be different if many universes existed with different settings. Observers would naturally find themselves in one that permits life. But no other universe has been directly observed, and we would need evidence that the proposed universes vary enough to explain what we see.
We have already looked at several reasons to believe in a rational Creator. If God intended to create life, this is the kind of universe we would expect Him to make. The conditions needed for life fit with purposeful creation. I think design explains those conditions better than treating them as a remarkable coincidence.
Bottom line: The conditions necessary for life are remarkably specific. Change certain settings of the universe, and life would not be possible. Given the evidence for a Creator we have already considered, I believe intentional design provides a better explanation for why our universe has these conditions.
Think about it: Why does a Creator offer an explanation for the universe's conditions?
Why design belongs in the explanation
Jordan goes back over the examples. “So the universe did not just need to exist. It needed the kind of settings that allow stars, chemistry, and life.”
“Right. And if those settings could have been different, then it is fair to ask why they fall in the life-permitting range.”
Jordan looks up at the stars again. “I guess saying ‘we are here, so of course we see a universe that allows life’ only explains why we can notice it. It does not explain why the conditions are there.”
He pauses. “I still want to know whether a multiverse can explain it, but I can see why design is a serious explanation, especially if there are already other reasons to think a Creator exists.”
Use what you learned in a different situation
A friend says, “I get that the universe has the right settings for life, but couldn't we have just gotten lucky? And if there are lots of universes, wouldn't one of them have to work? Why bring God into it?” How would you explain why design is a serious explanation of the evidence?
The full course lets you write your response, compare it with a model, and track your progress.
Practice this inside the full courseQuestions this argument still has to face
“Maybe we just got lucky.”
That is one possibility, but only a small fraction of the settings studied in many physical models allow life. If there is only one universe, it is worth asking why those conditions came together.
“There could be countless other universes.”
Possibly. A multiverse with many different settings could help explain why at least one universe supports life. But we have not directly observed another universe. We would need evidence that the proposed multiverse exists and produces the necessary range of conditions.
“Maybe the constants had to be this way.”
That would be an important finding. So far, no established theory has shown that all the relevant settings had to allow life.
“A Designer is not a scientific explanation.”
Science studies how the universe works. We can also ask why its basic conditions allow life in the first place. The arguments for a Creator from the earlier studies give us a reason to consider design here.
Use this in a real conversation
- Use the cosmological constant as your example. Explain how changing its value could prevent galaxies from forming.
- Tell people that only a small fraction of the settings examined in many physical models permit life. Avoid turning that finding into an exact one-in-so-many probability for our universe.
- If someone suggests a multiverse, ask what evidence supports it and whether its universes would have different conditions.
- Keep the positive argument clear: a Creator who intended life had a reason to make a universe capable of supporting it.
Keep the difference between a narrow range of life-permitting settings and the exact odds of an undesigned universe clear. We can compare settings within physical models without assigning a precise probability to the universe itself.
Sources for further study
- Luke Barnes | The Fine-Tuning of the Universe for Intelligent Life: Surveys physical examples, including galaxy formation, stars, and the cosmological constant, without arguing against theism.
- Robin Collins | The Fine-Tuning Design Argument: Explains why life-permitting conditions can count as positive evidence for an intentional Creator when compared with a single undesigned universe.
- Biola | Is Fine-Tuning Question-Begging?: William Lane Craig explains the difference between observed fine-tuning and the later argument that design best explains it.
- Reasonable Faith | What Is the Fine-Tuning Argument?: Provides a short, accessible introduction to the comparison between physical necessity, chance, and design.
- Hans Halvorson | Why Methodological Naturalism?: Explains why studying natural mechanisms in science need not amount to denying the existence of a Creator.
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