Although natural theology has been practiced for centuries, it was especially popular in the West after science arose but before religion began to wane—between the seventeenth and the nineteenth centuries. And it was part of the scientific toolkit. As we’ve learned, Isaac Newton invoked the action of God to stabilize planetary orbits. In the absence of other natural explanations, that was convincing at the time.
Perhaps the most famous argument for natural theology was that of the clergyman/philosopher William Paley, whose 1802 book Natural Theology (subtitled Evidences of the Existence and Attributes of the Deity) argued that the “design” of animals and plants gave convincing evidence for a beneficent God. His most famous argument involved the “camera” eye of humans, an organ so complicated and composed of so many interrelated parts that it simply couldn’t be explained by natural processes. As he said, “As far as the examination of the instrument goes, there is precisely the same proof that the eye was made for vision, as there is that the telescope was made for assisting it.” Even the young Darwin initially found this argument convincing, though he later refuted it decisively by showing that natural selection alone could produce organs as complex as the eye.
It’s a bit Whiggish to criticize early natural theology. At the time it could be seen as science, for it had the positive agenda of understanding nature using the best available explanations. Among the many phenomena thought to have a divine cause were mental illness, lightning, the origin of the universe, magnetism, and, of course, evolution. Natural theology was also scientific in that at least some versions went beyond post facto rationalizations to make predictions and testable claims. Creationism, for instance, makes claims about the age of the Earth, the absence of transitional forms between “kinds” of creatures, and so on. In 1859, it was a valid competitor to evolution, which is why Darwin spent so much time in On the Origin of Species showing how his new theories explained the data better than did creationism.
By the mid-nineteenth century, theology had finally lost its cachet as a form of science. This resulted largely from Darwin’s own dismantling of the best argument for God ever derived from nature, as well as from the success of physics and medicine in replacing religious explanations with natural ones. Its decline was also hastened by philosophy, as Hume and Kant had given cogent arguments against miracles, deliberate design, and the logical arguments for God.
Yet natural theology has recently had a comeback. This is partly due to the rise of “intelligent design,” which claims to identify evolutionary gaps fillable only by invoking an intelligent designer. While ID advocates argue that the designer is not necessarily the Judeo-Christian God—it could, they say, be an alien from another planet—this is disingenuous. The Christian roots of ID, and the private statements of its proponents, show that it’s intended to replace the “disease” of naturalism with purely Christian metaphysics. ID is simply creationism gussied up to sound more scientific, in a vain attempt to circumvent U.S. court rulings prohibiting religious incursions into public schools.
Criticisms of “god of the gaps” arguments go back as far as ancient Greece, as we see from a famous statement by the physician Hippocrates of Cos:
Men think epilepsy divine, merely because they do not understand it. But if they called everything divine they do not understand, why, there would be no end of divine things.
The theological dangers of this tactic were pointed out by Dietrich Bonhoeffer, writing from prison before the Nazis executed him for plotting against Hitler:
How wrong it is to use God as a stop-gap for the incompleteness of our knowledge. If in fact the frontiers of knowledge are being pushed further and further back (and that is bound to be the case), then God is being pushed back with them, and is therefore continually in retreat. We are to find God in what we know, not in what we don’t know.
Nearly everyone recognizes this problem, as did Ingersoll in the eloquent quote that heads this section. Yet believers continue to invoke God to explain unsolved scientific puzzles. This probably reflects a yearning not just for answers, but for answers that support the existence of one’s faith. This might explain the equivocation of some religious scientists. For instance, Francis Collins, perhaps America’s most visible scientist, is a strong opponent of intelligent design, and has repeatedly warned about using “god of the gaps” arguments:
A word of caution is needed when inserting specific divine action by God in this or that or any other area where scientific understanding is currently lacking. From solar eclipses in olden times to the movement of the planets in the Middle Ages, to the origins of life today, this “God of the gaps” approach has all too often done a disservice to religion (and by implication, to God, if that’s possible). Faith that places God in the gaps of current understanding about the natural world may be headed for crisis if advances in science subsequently fill those gaps.
Indeed. Yet in the same book Collins violates his own prescription, arguing that God is the best explanation for not only the “fine-tuning” of the universe’s physical constants, but also the innate moral feelings shared by most people.
The soothing feeling of having quasi-scientific evidence for your God is simply too alluring, leading even liberal believers to show the kind of ambivalence we saw in Collins. Here are some phenomena repeatedly cited by the new natural theology as evidence for God:
The fine-tuning of the physical constants that allow our universe (and our species) to exist
The existence of physical laws themselves
The origin of life from inanimate matter
The inevitability of human evolution
Instinctive human morality (the “Moral Law” described above by Collins)
The existence of consciousness
The reliability of our senses at detecting truth
The fact that the universe is even comprehensible by humans
The amazing effectiveness of mathematics in describing the universe
When facing “scientific” arguments for God like these, ask yourself three questions. First, what’s more likely: that these are puzzles only because we refuse to see God as an answer, or simply because science hasn’t yet provided a naturalistic answer? In other words, is the religious explanation so compelling that we can tell scientists to stop working on the evolution and mechanics of consciousness, or on the origin of life, because there can never be a naturalistic explanation? Given the remarkable ability of science to solve problems once considered intractable, and the number of scientific phenomena that weren’t even known a hundred years ago, it’s probably more judicious to admit ignorance than to tout divinity.
Second, if invoking God seems more appealing than admitting scientific ignorance, ask yourself if religious explanations do anything more than rationalize our ignorance. That is, does the God hypothesis provide independent and novel predictions or clarify things once seen as puzzling—as truly scientific hypotheses do? Or are religious explanations simply stopgaps that lead nowhere? As I explained in Why Evolution Is True, Darwin’s hypothesis for the change and diversity of life was accepted not just because it fit existing data but because it led to testable and verified predictions (e.g., where in the geological record would we find intermediates between reptiles and mammals?) and explained things that once baffled biologists (why do humans develop a coat of hair as six-month embryos, but then shed it before birth?). Intelligent design makes no such predictions or clarifications. Does invoking God to explain the fine-tuning of the universe explain anything else about the universe? If not, then that brand of natural theology isn’t really science, but special pleading.
Finally, even if you attribute scientifically unexplained phenomena to God, ask yourself if the explanation gives evidence for your God—the God who undergirds your religion and your morality. If we do find evidence, for, say, a supernatural origin of morality, can it be ascribed to the Christian God, or to Allah, Brahma, or any one god among the tho
usands worshipped on Earth? I’ve never seen advocates of natural theology address this question.
We’ve already covered one item on the list above: the “inevitability” of humans having evolved, which on inspection doesn’t seem so inevitable. As for the origin of life, we’ve made enormous progress in understanding how it might have happened beginning with inert matter, and I’d be willing to bet that within the next fifty years we’ll be able to create life in the laboratory under conditions resembling those of the primitive Earth. That doesn’t mean that it did happen that way, of course, for we’ll probably never know. But reproducing such an event would falsify the religious claim that a natural origin of life is simply impossible without God. And the religious answer hasn’t stopped the intense effort by chemists and biologists to find a naturalistic solution.
To the layperson, our consciousness seems scientifically inexplicable because it’s hard to imagine how the sense of “I-ness”—and our subjective sensations of beauty, pleasure, or pain—could be produced by a mass of neurons in our head. Yet consciousness subsumes at least four phenomena: intelligence, self-awareness, the ability to access information (being unconscious versus “conscious”), and the first-person sense of subjectivity. Only the last—the so-called hard problem of consciousness—seems baffling, for it’s difficult to imagine how a brain that can be studied objectively produces feelings that are subjective. Neuroscience has already made substantial inroads on the first three phenomena (brain interventions, both mechanical and chemical, as well as scans of brain activity, are putting together a neurological picture of what’s required for these phenomena), and that field is already knocking on the door of the hard problem. Ultimately, its solution may elude us for one reason: we’re using our limited cognitive abilities to tackle a research project that is hard even to frame. That doesn’t mean that we should abandon this work, only that the most recalcitrant problem of science isn’t the origin of life, or the origin of the laws of physics, but the evolution and mechanics of our brains and the minds they produce. This is the result of a peculiar recursion: we’re forced to use an organ that evolved for other reasons to study how that organ makes us feel.
The “problems” of the laws of physics and the effectiveness of mathematics are connected, but only the first needs explanation. It’s important to realize at the outset that the very term “laws of physics” is tendentious, for the word “law” implies a lawgiver, implying a creative god. But the laws of physics are simply observed regularities that hold in our universe, and I’ll use “laws” in that sense alone.
And those laws are in fact a precondition of our existence, for without them we couldn’t have evolved—or even existed as organisms. And by “we,” I mean all species. If the laws of physics and chemistry varied unpredictably, our brains and bodies wouldn’t work, for we couldn’t have stable physiology, genetic inheritance, or the ability to reliably collect and process information about the environment. Imagine what would happen, for instance, if the impulses in our nerves, which depend on chemistry, traveled at widely variable speeds. Before we could pull our hand from the fire, or detect a predator, we might be burned or eaten. If we couldn’t control the acidity of our blood within a fairly narrow range (one of the functions of our kidneys), we’d die. Nor could evolution have operated, for that process depends on environments being fairly constant from one generation to the next. If that constancy didn’t exist, no species could last for long.
Thus, as with the “fine-tuning” problem of the laws of physics, which we’ll discuss shortly, we can devise an “anthropic principle of biology”: there must be stable laws of physics, or life wouldn’t have evolved to the point where we could discuss these laws. Where natural theology comes in, as it does with physical laws, is the claim that the laws are “fine-tuned” by God to permit the existence of humans.
But if there are such laws, then the usefulness of mathematics is automatically explained. For mathematics is simply a way to handle, describe, and encapsulate regularities. As you might expect, there is in fact no law of physics—no regularity of nature—that has defied mathematical description and analysis. In fact, physicists regularly invent new types of mathematics to handle physical problems, as Newton did with calculus and Heisenberg with matrix mechanics. It’s hard to conceive of any regularity that couldn’t be handled by mathematics. So “the unreasonable effectiveness of mathematics in the natural sciences,” as the physicist Eugene Wigner titled one of his scientific papers, simply reflects the regularities embodied in physical law. The effectiveness of math is evidence not for God, but for regularities in physical law.
One of the enduring goals of physics is to derive more fundamental laws from less fundamental ones: that is, to unite seemingly disparate phenomena under a single theory that reduces the number of subtheories. Classical Newtonian physics, for example, is now seen as a special case of quantum mechanics, and thermodynamics as a special case of statistical mechanics. The attempt to find a “theory of everything” unifying the four great forces of physics has been largely successful: so far only gravity has eluded union with the strong, weak, and electromagnetic forces. It is likely that this kind of amalgamation will continue on many levels, but it’s also likely that in the end we’ll reach a set of principles or descriptors that can be reduced no further. At that point we’ll simply have to say, “These are, as far as we know, the irreducible laws of our universe.” But what does it add to our understanding to say “and these laws are God’s creation”? It adds nothing, but merely yields another unanswerable: where did that God come from?
But the existence of physical laws, even if we can’t understand their constancy, raises a separate question. Even if those laws are required for our existence, why are they such as to allow our existence? To many believers, the answer is “Because God deliberately made them compatible with human life so that we, his most special creature, could evolve.”
This brings us to the most pervasive—and, to the layperson, the most convincing—claim of natural theology: that of the “fine-tuning” of physical laws. After discussing it, I’ll take up the remaining natural theological arguments for God: the “Moral Law” and our ability to hold beliefs that are true.
The Argument for God from “Fine-Tuning”
The “fine-tuning” argument for God, also known as the “anthropic principle,” makes the following claim: Many of the constants of physics are such that if they differed even slightly, they would not permit the existence of our universe or the evolution and existence of humans who were supposedly the object of God’s creation. Because we do exist, the values of these constants are too improbable to be explained by science, which suggests that they were adjusted by God to make life possible.
A full 69 percent of Americans support some version of this argument, agreeing that “God created the fundamental laws of physics and chemistry in just the right way so that life, particularly human life, would be possible.” Even scientists are susceptible to the argument. Kenneth Miller has decried “god of the gaps” arguments, but relents a bit when those arguments involve physics:
It almost seems, not to put too fine an edge on it, that the details of the physical universe have been chosen in such a way as to make life possible. . . . If we once thought we had been dealt nothing more than a typical cosmic hand, a selection of cards with arbitrary values, determined at random in the dust and chaos of the big bang, then we have some serious explaining to do.
The “serious explaining,” of course, includes considering God.
But at the outset we must ask whether the constants of physics really do fall within a narrow range that permits human life. The answer is yes—but for only some of them. The constants that could not vary much from their measured values without making life as we know it impossible—and we’ll need to discuss the meaning of “life as we know it”—include these: the masses of some fundamental particles (for example, protons and neutrons), the magnitude
of physical forces (the strong and electromagnetic forces, as well as gravity), and the “fine structure” constant (important in forming carbon). If gravity were too strong, for example, planets could not exist long enough for life to evolve, nor would organisms be possible, as they would be flattened. The mass of the proton is 99.86 percent that of the neutron, and if it were even slightly smaller, stars like the Sun couldn’t exist, for the nuclear fusion that powers their existence could not occur.
The observation that some constants must be close to what they are to make life physically possible is called the “weak anthropic principle.” And it seems easy to refute this as evidence for God. If the constants didn’t have those values, we wouldn’t be here to measure them. Of course they must be consonant with human life.
But theists claim more than that, proposing what is called the “strong anthropic principle.” This principle is simply the weak version with the added explanation that the constants fall within a narrow range of values because that’s where God put them. As the argument goes, the values of those constants are highly improbable among the array of all possible physical constants, and because their values currently defy scientific explanation, that improbability is evidence for God. This is, of course, a “god of the gaps” argument, resting on our ignorance about what determines physical constants. But because this principle sounds authoritative and involves arcane issues of physics unfamiliar to the average person, it is often invoked by theists. It is in fact the most effective weapon in the arsenal of the new natural theology.
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