Thursday, September 22, 2016

Robin Collins's Fine-Tuning Argument for God's Existence

Monroe County Community College
(For my MCCC Philosophy of Religion students)

Oral Exam Question #5 - Explain Collins's Fine-Tuning Argument for God's existence.

1. Give the "biosphere" example.

2. The universe is analogous to such a biosphere.

3. The universe is "fine-tuned" for our existence. For example, "If gravity did not exist, masses would not clump together to form stars or planets, and hence the existence of complex, intelligent life would be seriously inhibited." (The gravitational constant is an "anthropic coincidence," or "cosmological constant." Stephen Hawking et. al. acknowledge the fine-tuning - see below.)

4. State the argument:

  • Premise 1. The existence of the fine-tuning is not improbable under theism.
  • Premise 2. The existence of the fine-tuning is very improbable under the atheistic single-universe hypothesis.
  • Conclusion: From premises (1) and (2) and the prime principle of confirmation, it follows that the fine-tuning data provides strong evidence in favor of the design hypothesis over the atheistic single-universe hypothesis.

5. The "prime principle of confirmation" is: whenever we are considering two competing hypotheses,  an observation counts as evidence in favor of the hypothesis under which the observation has the highest probability (or is the least improbable). 

Note: Collins also calls the "prime principle of confirmation" the "likelihood principle."

For a more recent discussion see:

Robin Collins, "The Fine-Tuning Argument Is Convincing," and

Victor Stenger, "The Universe Shows No Evidence for Design,"

both essays in Debating Christian Theism, eds. J.P. Moreland, Chad Meister, and Khaldoun A. Sweiss


1. Hawking and Mlodinow's The Grand Design can be understood as an atheistic response to the fine-tuning argument. They acknowledge the appearance of fine-tuning:

"Most of the fundamental constants in our theories appear fine-tuned in the sense that if they were altered by only modest amounts, the universe would be qualitatively different, and in many cases suitable for the development of life. For example, if the other nuclear force, the weak force, were much weaker, in the early universe all the hydrogen in the cosmos would have turned to helium, and hence there would be no normal stars; if it were much stronger, exploding supernovas would not eject their outer envelopes, and hence would fail to seed interstellar space with the heavy elements planets require to foster life. If protons were 0.2 percent heavier, they would decay into neutrons, destabilizing atoms... The emergence of the complex structures capable of supporting intelligent observers seems to be very fragile. The laws of nature form a system that is extremely fine-tuned, and very little in physical law can be altered without destroying the possibility of the development of life as we know it." (Grand Design, 160-161)

But, for Hawking and Mlodinow, "the multiverse concept can explain the fine-tuning of physical law without the need for a benevolent creator who made the universe for our benefit." (165)

Collins responds to this in his essay. For the purposes of our class we will not discuss the multiverse issue, important as it may be.
2. The anthropic objections plays an important part in Hawking and Mlodinow's objections to the fine-tuning argument. Collins, in citing John Leslie's "fire squad" analogy, writes:
"According to the weak version of so-called  anthropic principle, if the laws of nature were not fine-tuned, we would not be here to comment on the fact.  Some have argued, therefore, that the fine-tuning is not really improbable or surprising at all under atheism, but simply follows from the fact that we exist. The response to this objection is simply to restate the argument in terms of our existence: our existence as embodied, intelligent beings is extremely unlikely under the atheistic single-universe hypothesis (since our existence requires fine-tuning), but not improbable under theism.  Then, we simply apply the prime principle of confirmation to draw the conclusion that our existence strongly confirms theism over the atheistic single-universe hypothesis."

Collins then gives Leslie's example to illustrate this.