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The Argument from the Fine-Tuning of the Universe

In high school, as I learned about apologetics, I was enthralled by the universe. When we look up at the night sky, we see what seems to be tiny lights, which are actually massive balls of hydrogen millions of millions of miles away. The vastness of the universe, which we've only discovered in the last few hundred years, is incomprehensible. As we learn more and more about the mechanisms operating in this universe that make it ordered and even habitable, we discover that, from the beginning, the odds were stacked against us. Way against us.

Just think about it. Let's consider the force of gravity. Gravity is a force in the universe that we still struggle to understand, but we know how to measure it. It was Isaac Newton (1643-1727) who first discovered that the force of gravitation, the force that attracts two bodies to each other, is the product of the masses of those two bodies and is inversely proportional to the square of the distance between them. In other words, the force of gravitation between two bodies is determined by their masses and how far they are away from each other. This is the equation that measures this force:

In this equation, G is a constant. Constants are elements in equations that stay the same; the number just is what it is. In recent decades, scientists have discovered that the so-called constants and quantities, which determine the laws of physics, are such that they permit life in the universe. Had any of these constants and quantities been outside of the life-permitting range, the universe would not have supported life. They also discovered that, for each of these constants and quantities, the life-permitting range is incredibly small, compared to the possible values that they could have taken. Someone once compared it to a ruler stretching from one end of the observable universe to another. On this ruler, the life-permitting range is a single inch. This begs the question: why is our universe so fine-tuned for life? This is the argument from the fine-tuning of the universe. Here's the video:

As you can see from the video, the gravitational constant is one of many values that are fine-tuned for the existence of life in the universe. The constants have a place in certain equations for the various laws of physics, whereas the quantities are certain arbitrary values (e.g., the amount of entropy in the early universe) that seemed to be "put in." In other words, there seems to be nothing that determines why those values are what they are.

One clarification is in order. As you can see from the video above, this is an argument for the existence of God because the argument proposes that God is the best explanation for the fine-tuning of the universe. In other words, this is a type of argument from design (also called a teleological argument). Because of this, it can be easy to think that "fine-tune" means "designed," but this is not what scientists mean when they say that the universe has been fine-tuned. By fine-tuned, scientists mean that the universe seems to be particularly adjusted for the existence of life. To be more precise, it seems like any universe that exists must be fine-tuned in order for that universe to be life-permitting, since each of these values must fall within an exceedingly small life-permitting range. This is important because it dispels the misunderstanding that fine-tuning entails design by definition.

Let's now analyze the logic of the argument. In order to understand this argument, we need to understand another rule of logical inference called disjunctive syllogism. If you read last week's post on the argument from contingency, then you know that a disjunction is an either/or statement. In symbolic logic, we write a disjunction like this: p v q, where "v" means "or." The disjunctive syllogism is a rule by which, if you can show that either p or q is false, the remaining option is therefore true. This is how a disjunctive syllogism looks in symbolic form:

Disjunctive Syllogism

  1. p v q

  2. not-p

  3. Therefore, q

With this rule of inference in mind, let's look at the syllogism in English:

  1. The fine-tuning of the universe is due to either physical necessity, chance or design.

  2. It is not due to physical necessity or chance.

  3. Therefore, it is due to design.

In order to properly symbolize this argument, we need to recognize that the first premise is a disjunction. The first premise presents three possible options for explaining the fine-tuning of the universe: physical necessity, which we will call N; chance, which we will call C; and design, which we will call D. Here is the first premise:

N v C v D

In English, we could read this premise as, "The fine-tuning of the universe is due to physical necessity; or the fine-tuning universe is due to chance; or the fine-tuning of the universe is due to design." The second premise posits that N and D are false. For the sake of simplicity, I will list these as two separate premises. Here is the entire argument symbolized:

  1. N v C v D

  2. not-N

  3. not-C

  4. Therefore, D

Thus, we can see that since the argument follows the rule of disjunctive syllogism, the argument is therefore valid.

How about defending the premises? The first premise is quite simple; these are the only three explanations on offer right now. If someone could provide a fourth explanation, then it could simply be incorporated into the premise.

As for the rest of the premises, the video does a good job of defending them. I'll simply list them here:

Premise 2

Physical Necessity:

  • Very difficult to see how the laws of nature could have, in a deterministic way, determined the constants and quantities to be what they are, since these constants and quantities are independent of the laws of nature

  • At face value, extremely improbable, since it amounts to the claim that the constants and quantities could not have been outside the life-permitting range


  • Again, extremely improbable at face value, since life-prohibiting universes are incomprehensibly more probable than life-permitting universes

  • Proposed mechanisms supporting chance, such as the multiverse, are scientifically untenable and require fine-tuning, which moves the need for an explanation back a step

What are strengths of this argument? In my post on the argument from the beginning of the universe, I quoted Psalm 19:1-2:

"The heavens are telling of the glory of God; And their expanse is declaring the work of His hands. Day to day pours forth speech, And night to night reveals knowledge."

In that post, I said that the universe is telling us something. For the last 150 years, some of the most important discoveries in cosmology have left scientists in awe and atheists scrambling for alternative explanations. And of course, alternative explanations and arguments abound. But at what point does the astounding beauty and complexity of this universe compel us to give glory to the only One powerful enough to create all of it from nothing? This is a strength of the argument from fine-tuning. The fact of fine-tuning doesn't just puzzle scientists; for many, it overwhelms them. I've found personally that when I think of fine-tuning, I see the splendor and majesty of the God who not only thought of all of this but made it happen alone and without any help. The idea that physical necessity or chance, especially, could explain this seems ridiculous to me. What an awesome God!

That's it for this week's post! If you have any comments or questions, feel free to leave a comment or send me an email or message. I hope that these arguments continue to interest and edify you. Next week, we'll discuss the moral argument. This fascinating argument tends to be very compelling, since it speaks to human experience in an intimate way. Stay tuned for that post!

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