I have written about how the idea that the Universe is fine-tuned for life has become the most common cosmological argument for the existence of God. Recently, I have been thinking more about the fallacy in this argument. My thinking has been stimulated by reading some work by Simon Friedrich--particularly, his article on "Fine-Tuning" for the Stanford Encyclopedia of Philosophy and his book Multiverse Theories: A Philosophical Perspective (Cambridge University Press, 2021).
According to many physicists, it is surprising that the Universe supports life--and particularly human life--because this depends precisely on certain fundamental characteristics of the Universe--the quantitative values of some constants of nature, the form of the laws of nature, and the conditions in the early universe. Even slight variations in these values, laws, and conditions would have made life impossible. As one example, if the strength of gravity had been only slightly weaker or slightly stronger than it is, stars and planets could not have formed in the way they are today, and thus there would have been no habitable planet for life. There is a long list of physical constants like gravity that had to be "just right" for a Universe favorable to life to exist. Sometimes this is called the "Goldilocks principle": the porridge needs to be not too hot and not too cold but just right.
In this way, the Universe appears to be fine-tuned for life. Why? Theistic creationists can say that if the Universe is fine-tuned, that must be because there is a divine fine-tuner. Or is there some better explanation?
From the start, we should recognize that saying the Universe is fine-tuned is a metaphorical use of the term fine tuning. Metaphor is a form of reasoning in which we understand one thing through its resemblance to something else. We need to be careful that our metaphorical reasoning does not lead us into the fallacy of equivocation in which we deceptively call two different things by the same name. And my argument is that the idea of the fine-tuned Universe commits that fallacy of equivocation.
The Oxford English Dictionary gives three definitions of "fine tuning." The primary definition is "the action or process of tuning a musical instrument very precisely, so as to play at exactly the correct pitch." The second definition is: "Originally: the action or process of making minor adjustments to a radio in order to receive or broadcast on specific frequencies. In later use more generally: the action or process of making minor adjustments to a device, apparatus, etc., in order to achieve a precise setting or calibration." The third definition is: "The action or process of minor adjustments to something in order to achieve the best or a desired performance; (Economics) the policy or process of making a series of minor changes in monetary and fiscal policy in order to maintain a stable level of aggregate demand, usually that associated with full employment."
Notice that these definitions concern technological devices (such as musical instruments or radios) or social technology (such as planning an economy) in which human beings adjust technological artifacts or social institutions so that they function to satisfy human desires. The fine-tuning is the product of human fine-tuners. And we understand how this works because of our common experience of how human beings design, make, and control physical and social tools so that they function in desirable ways.
If this is what we mean by fine tuning, are we right in saying that the Universe is fine-tuned? Or is this a deceptive equivocation--because the idea of fine tuning assumes human beings as the fine tuners, and it would be ridiculous to assume that the Universe was fine-tuned by human beings? Presumably, if there were cosmic fine tuners, they would have to be supernatural or transcendent beings with the divine intelligence and omnipotence that allow them to create the Universe as they will. But our ordinary human experience of human fine tuning tells us nothing about divine fine tuning.
In previous posts, I have shown how the argument for intelligent design is an argument from equivocation in the use of the term "intelligent design." Both William Dembski and Michael Behe speak of "intelligent design" without clearly distinguishing human intelligent design from divine intelligent design. We have all observed how the human mind can cause effects that are humanly designed, and from such observable effects, we can infer the existence of human intelligent designers. But insofar as we have never directly observed a disembodied, omniscient, and omnipotent intelligent designer causing effects that are divinely designed, we cannot infer a divine intelligent designer from our common human experience.
Behe is right that from an apparently well-designed mousetrap, we can plausibly infer the existence of a human intelligent designer as its cause, because we have common experience of how mousetraps and other human artifacts are designed by human minds. In the same way, William Paley was right that from a well-designed watch, we can plausibly infer the existence of an intelligent human watchmaker. But from an apparently well-designed organic mechanism (like the bacterial flagellum), we cannot plausibly infer the existence of a divine intelligent designer as its cause, because we have no common experience of how a divine mind designs things for divine purposes.
Dembski has written: "The point of the intelligent design program is to extend design from the realm of human artifacts to the natural sciences." This sophistical rhetorical strategy of equivocation in the use of the term "intelligent design" hides the fact that while detecting the design of human artifacts is a matter of common observation and inference, detecting the design of divine artifacts is not.
Similarly, if we hear a musical instrument that has been fine-tuned, we can infer the existence of some human fine-tuner, because we understand how musical instruments need human fine-tuners. But if the Universe appears fine-tuned for life, we cannot say that this proves the existence of a divine fine-tuner, because we have no experience with or understanding of a divine being creating the Universe so that it is fine-tuned for life.