March 30, 2020

The Intriguing, Seductive and Ultimately Unsatisfying Anthropic Principle

Some believers in a traditional deity deny, or at least are skeptical about, certain claims of science. The issue may be the origin of the universe in a Big Bang, the age of the universe, the nature of the evolution of life on Earth or some other proposition.  In these instances, the believers see science as inconsistent with, even in opposition to, a sacred truth revealed in some literature such as the Torah, the Christian Bible or the Qur’an, and therefore should be rejected.

On other occasions, though, believers will embrace science. They will hear that the initial conditions of the universe, certain laws of nature or the location and chemistry of our planet are set within a limited range that allows for human existence — a proposition sometimes called the Anthropic Principle (i.e., relating to humankind) — and take those conditions and characteristics as proof of a personal god. They will understand a “fine-tuned” universe as demonstrating, or at least strongly implying, the existence of a Fine-Tuner, a Devine Designer.

Drawing a conclusion about the existence of God from certain natural phenomena is not, of course, a new idea. Well over two thousand years ago, the author of Psalm 19 wrote that “the heavens declare the glory of God” and “His handiwork is proclaimed by the firmament.” (Psalm 19:1.)

Centuries later, we find an early Jewish version of the Watchmaker argument.  Responding to a heretic  who asked him who made the universe,  Rabbi Akiba reportedly said: “Just as a house attests to its builder, a garment to its weaver or a door to its carpenter, so too does the  world attest to the Holy One who created it.” (See “>Mordecai Kaplan, can be attracted to the argument from nature. Kaplan found evidence for God in “the oneness that spans the fathomless deeps of space” and “the elemental substance of stars and planets, of this our earthly abode and of all it holds.” (See Scult, The Radical American Judaism of Mordecai M. Kaplan (Indiana U. Press 2014 ) at 150-51.)

Science has advanced considerably since the day of the psalmists and Akiba, and since Kaplan’s time, too. And the argument based on the observation and understanding of natural phenomena has been refined accordingly.

 In his popular book, Just Six Numbers (Basic Books 2000), British cosmologist“>Dr. Hugh Ross  generated “>updated his list in 2006 to include over ninety values.

The Anthropic Principle has been adopted on occasion by orthodox Jewish scientists such as “>Nathan Aviezer, each of whom seeks to promote the notion of a close and harmonic relationship between the Torah and modern science. Schroeder, a physicist now residing in Israel, is best known perhaps for his attempt to conflate the six days of Biblical creation and the fourteen billion years of cosmological evolution into the same time period. (See generally, The Science of God (“TSOG”) (Free Press 1997), discussed “>here and “>here.)

Rather than review fourteen billion years of cosmological evolution, Aviezer, a physics professor at Bar-Ilan University in Israel, “>Roger Penrose who,  in The Emperor’s New Mind (Oxford 1989), calculated the likelihood that we would find ourselves in an environment suited for life at “less than one chance out of ten to the power of ten to the power of 123” (TSOG, at 192-93), that is, “1” followed by 10123 “0”s. One in a billion (109) would  seem to be exceptionally small (except perhaps to a university mathematician), but this number is so many zillion times smaller it literally cannot be written out, much less be expressed or understood with any precision.

Aviezer also devotes some space to the issue of calculating probabilities, but instead of revealing a particular number, merely concludes that the events leading to human life on Earth were “extremely unlikely.” He adds that the “extreme rarity of the events . . . is well established.” Consequently, he claims that “the anthropic principle has become a scientifically established fact.”

Well, not quite. There are problems with the Anthropic Principle, some definitional, some philosophical, some empirical.

The first problem with the Anthropic Principle is that there is no agreement on what it is. The term itself was invented relatively recently, apparently by British cosmologist Brendan Carter around 1974. In contrast to the Copernican revolution, which denied that humankind was at the center of the universe, the purpose of the Anthropic Principle (the “AP”) is to “portray the cosmos less as an impersonal machine and more as . . . a ‘home to Man.’” (Ferris, The Whole Shebang (Simon & Schuster 1997) at 292.)

In the last forty years, others have proposed variations on the theme. For instance, some claim that there is a Weak Anthropic Principle (“WAP”) and a Strong Anthropic Principle (“SAP”) among other APs. WAP asserts that the laws of nature must be such as to “permit the emergence of life” while SAP asserts that the universe must also allow for “’the creation of observers in it.’” (See Id. at 299.)

In addition, some writers have discussed PAP, the Participatory Anthropic Principle, and FAP, the Final Anthropic Principle. The late, great science writer “>Hayden Planetarium Director Neil DeGrasse Tyson and “>Physicist Timothy Ferris asserts that the AP “is less scientific than philosophical.” (See Ferris, above, at 300.) Even so, the AP fails. Martin Gardner considered himself a philosophical theist, but he had a “dim view” of the AP, and thought that the fine-tuning argument for God was “logically fragile.” (See “Proofs of God,” in The Night is Large, above, at 539-540, 546.)  As Gardner recognized, if the AP is read as proclaiming that “because we exist the universe must be constructed as to allow us to have evolved,” then it is nothing more than a “trivial tautology.” (See “WAP, SAP, PAP, and FAP,” above, at 41.)

More formally, the AP contends that because B (humankind) chronologically follows A (the original conditions for the universe), that A caused B, or in the phrasing of the AP, that A was fine-tuned for B. This backward reasoning is a form of “retrograde analysis” in which observations about the present are the basis for speculation about the past.  (See “Proofs of God,” above, at 539-41.) The fallacy is known as the post-hoc fallacy. (See Ferris, above, at 300.) What is more accurate is that through a natural process of cosmological and then organic evolution, including natural selection and adaptation, over a long period of time human life emerged. Rather than the universe being suited for humankind, humankind and its predecessors adapted to the universe that was available.

The AP also fails to conform to reality. To assert as a principle that our universe is fine-tuned for life is contrary to some rather obvious facts. Only about four percent (4%) of the universe is made up of conventional (baryonic) matter, with almost all of the balance being composed of dark energy (~70%) and dark matter (~25%), about both of which we know precious little. (See Adams, above, at 55.) What we do know is that almost all of the universe is empty and frigid, and, because of accelerating expansion, getting visually emptier and colder.  (See Id. at 60, 62-63, 219-20.) So, it is not surprising that to date we have no evidence of any life, much less intelligent or human-like life, on other planets.

Even on our planet, life flourishes in a limited number of locations. And where it does is often a scene of harsh and bitter struggle.  If the universe really were fine-tuned for life, especially human life, then why isn’t it flourishing and visible? And why would a Fine-Tuner create such vast amounts of wasted space and a system dependent on conflict? Conversely, if our search for extraterrestrial life is successful, what does that mean for the AP? Does that confirm that the universe is fine-tuned for life or does it suggest that life is not as unique as we once thought? And what if that life is not human?

The AP is also premature. The universe is just shy of fourteen billion years old. Our genus emerged about two million years ago, with our species, Homo sapiens, arriving about 300,000 years ago. (See Coyne, Why Evolution is True (Penguin 2009) at 203, 206.) So, we have been around for just two ten thousandths of one percent of the life of the universe. For the other 99.9+% of the time, it would not have been at all obvious or perhaps even plausible that humankind would arise.

Similarly, the complete story of human existence on the home planet has not yet been written. If,  in the next one thousand or one hundred thousand years,  another massive meteor struck the earth triggering extinctions, including of us, would that mean the Anthropic Principle was false? Or just a temporary principle?

But what about the long odds on us being here, of each cosmological constant and ratio being just right to allow for the universe to form and evolve sufficiently for heavy elements to be formed in stellar nuclear reactions, spewed into space, and collected in a solar system which includes a planet at just the right distance from a correctly sized and aged single star and with just the right chemistry to allow for life to emerge?

Let’s start by considering the probability that any human now alive would be alive today. Each of us is the product of some twelve thousand generations of human evolution over the last 300,000 years. Each of those generations is the product of the fertilization of a reasonably random egg by an even more random sperm. Change the egg or the sperm in any one of those encounters and the current beneficiary of the process would not be here. The retrograde analysis of the AP would argue that we should not be here, but we all are – despite the odds. To “>Physicist Victor Stenger argues, essentially, that the probability question is misplaced. He contends that there is, in fact, nothing unusual about the processes that preceded our existence or the situation in which we find ourselves. He argues, in short, that the values identified by Rees or Ross are within the range one would expect from “established physics.” (See generally, The Fallacy of Fine Tuning (Prometheus Books 2011).)

Now, if you are having problems with the Schroeder/Aviezer claim that the universe is as God designed it, and you don’t like Stenger’s view that the universe is what it naturally is, there is another option. Martin Rees, among others, finds “compellingly attractive” the admittedly speculative theory that ours is but one of many universes. (See Rees, above, at 166.) Postulating a theoretical multiverse naturally improves the odds that a universe like ours would be among other universes, and Rees is, therefore, not surprised our number came up. (See also, Carroll, “>Rabbi Jonathan Sacks thinks so, which is one reason why he favors “a single unprovable God over an infinity of unprovable universes.” (See Sacks, The Great Partnership (Schocken  2011), at 269; but see also, Stenger, above, at 292.).)

In sum, the Anthropic Principle is an intriguing and seductive but ultimately unsatisfying concept for believers and non-believers alike. Its adoption by believers in support of a supernatural god is understandable, but it does not really advance their claim, does not provide proof. Nor is it even necessary for a believer to rely on, or even refer to, the AP. As Rabbi Sacks teaches, “faith is the defeat of probability by the power of possibility.”  (Id. at 283.)

Non-believers, too, are attracted to the AP for its purported non-theistic explanation of the seeming miracle of our existence. Some, conscious of the apparent overwhelming improbability of that existence, seek to improve the odds by changing the number of universes under discussion. But, based, on the available data, there is no reason to think that what we observe is anything other than what one would have expected from the normal operation of physics and chemistry, over time, and adding new universes, for which there is no current observable evidence, does not make the argument stronger or resolve the logical fallacies inherent in the AP.

At its core, the AP represents a return to pre-Copernican thinking, placing humanity, if not at the physical center of the universe, certainly as the reason for the origin and evolution of the universe.  But we do not need to regress. The fact of our existence, even if not at the center of our universe but just on a speck of rock at the outer spiral of a conventional galaxy in an obscure region of space, is in and of itself reason enough for wonder and joy. And the truths of our emergence from stardust and our historic relationship to each other, to all of life, to all matter and all energy are truths to be cherished and nurtured with humility and gratitude.

Amen or Q.E.D., as you prefer. 


Another version of this post was published previously at