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#625 Formulating the Fine-Tuning Argument

April 07, 2019

Hi Dr.Craig

In one of the recent forum discussions on your very own site, an objection about the reasoning of the FTA was put up. Basically what has been argued for is that the FTA suffers from the prosecutors fallacy.

p1:Science shows that the universe is fine tuned for life.

P2: its either due to chance, necessity or design.

p3 its not due to chance or necessity.

C: Therefore its due to design.

What has now been objected to is that the probability of chance and necessity are so low that you just swipe them off and take design without even considering the possibility/ probability of design. What also has been argued is that you can just switch up the position in the argument but that would leave the premises unjustified.

P1: science shows the universe has been fine tuned for life.

P2: this was either due to chance, necessity or design.

P3: it was not due to necessity or design.

C: Therefore its due to chance.

The main point of the question is: Why arent we looking at the probability of design and just assuming it?



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Dr. craig’s response


Luca, thanks for drawing our readers’ attention to the Open Forum on our website, where any question is up for discussion!

The short answer to your question is that I do look at the probability of design rather than just assume it.

What needs to be appreciated is that in my public debates I always try to present as simple a formulation of a theistic argument as possible in order to make it easy to understand and remember. What you see in a debate is just the tip of the iceberg. I frequently find that objections are posed to these arguments that are dealt with in my published work. Unfortunately, too few people ever go beyond the YouTube video and read what I’ve written on the subject.

So with respect to the fine-tuning argument, it is an inference to the best explanation, which I have formulated deductively for the sake of simplicity and clarity. We are basically looking at the three viable options for explaining cosmic fine-tuning.  So, of course, we must assess the probability of each alternative, including design. If the design hypothesis has an abysmally low probability, then it may turn out to be worse than the admittedly weak explanations of necessity or chance. In that case, premiss 2 “It is not due to necessity or chance” would not be justified. So in order to establish premiss 2 we have to look at the probability of the design hypothesis to see if there is any reason to think it terribly low.

So, for example, in response to Richard Dawkins’ critique of the fine-tuning argument, I say,

The fine-tuning of the universe is therefore plausibly due neither to physical necessity nor to chance.  It follows that the fine-tuning is therefore due to design, unless the design hypothesis can be shown to be even more implausible than its competitors.

Dawkins contends that the alternative of design is, indeed, inferior to the Many Worlds hypothesis.  Summarizing what he calls “the central argument of my book,” Dawkins insists that even in the admitted absence of a “strongly satisfying” explanation for the fine-tuning in physics, still the “relatively weak” explanations we have at present are “self-evidently better than the self-defeating   . . . hypothesis of an intelligent designer.”[1]

Really?  What is this powerful objection to the design hypothesis that renders it self-evidently inferior to the admittedly weak Many Worlds hypothesis?[2]

I go on to explain why Dawkins’ attempt to show that the design hypothesis is not as good an explanation as chance is a failure. That permits me finally to conclude: “Therefore, of the three alternatives before us—physical necessity, chance, or design—the most plausible of the three as an explanation of cosmic fine-tuning is design.”

Obviously, one cannot flip this argument so that chance is the preferred explanation because in that case the re-formulated second premiss “It was not due to necessity or design” is clearly false, since design is a better explanation than chance.


[1] Richard Dawkins, The God Delusion (New York: Houghton-Mifflin, 2006), p. 158.

[2] See my lecture “Deconstructing New Atheist Objections to the Arguments for God,” 

<https://www.youtube.com/watch?v=sm0hI2SUinQ>; cf. my article “The New Atheism and Five Arguments for God,” https://www.reasonablefaith.org/writings/popular-writings/existence-nature-of-god/the-new-atheism-and-five-arguments-for-god/.

- William Lane Craig