Feder and Zimmer use philosopher/physicist Robin Collins's version as representative of this approach. Collins's argument is succinct and relies on what he calls the Prime Principle of Confirmation which states that “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).”
In other words, we should always favor the hypothesis which is most probable over competitors that are less probable. Thus, Feder and Zimmer write:
Feder and Zimmer go on to mention a few difficulties:His [Collins's] justification for premise 1 is that “since God is an all good being, and it is good for intelligent, conscious beings to exist, it is not surprising or improbable that God would create a world that could support intelligent life.”
- 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.
His justification for premise 2 is the incredibly small likelihood of the constants having the proper values necessary by chance alone. Putting these together, he argues that fine-tuning strongly supports the hypothesis that an intelligent cause set the values of the constants.
Since we don’t know the probability distribution of each constant, it would seem that we can’t truly compute the relevant probabilities. This problem is addressed by Collins, Barnes, and multiverse scientists (who believe that the constants are set by chance).The second problem they discuss seems to me to be less weighty:
They use plausible upper and lower bounds for the constants and then assume the probability distribution for the constants is linear. Though these seem to be reasonable assumptions, the objection still carries some weight.
A second problem with this formulation is, do we really know the probability that God would want to create a complex universe with intelligent, conscious, moral agents?Intelligent design theorists could obviate this difficulty, however, by restating the version of the argument given above this way:
While this approach only needs the supposition that this probability is larger than the vanishingly small probability of fine-tuning assuming no intelligent cause, it could nevertheless be argued that God’s will is inscrutable and positing any knowledge about what God should do is engaging in a form of “divine psychology.”
- Premise 1. The existence of the fine-tuning is not improbable under the hypothesis that the universe is intentionally designed.
- Premise 2. The existence of the fine-tuning is very improbable under the naturalistic 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 hypothesis that the universe is intelligently designed.