A Universe Made for Us? Some Philosophy and Physics

The Anthropic Principle raises issues in philosophy and physics.

Posted Nov 12, 2018

In my last post, I introduced a discussion of the "anthropic principle," the idea—taken seriously by the religiously inclined and even a few physicists—that the physical nature of the universe was structured to accommodate human beings, because even a small change in many crucial physical constants would have made our existence impossible. The anthropic principle exists in two primary forms, often designated “strong” and “weak.” Over-simplifying, the weak principle is teleological, stating that whatever conditions are observed in the universe must allow the observer to exist. In short, if these constants weren’t as they are, we wouldn’t be around to worry about them. Physicist Roger Penrose explained the weak form as follows:

The argument can be used to explain why the conditions happen to be just right for the existence of (intelligent) life on the Earth at the present time. For if they were not just right, then we should not have found ourselves to be here now, but somewhere else, at some other appropriate time.... At any other epoch, so the argument ran, there would be no intelligent life around in order to measure the physical constants in question—so the coincidence had to hold, simply because there would be intelligent life around only at the particular time that the coincidence did hold.[i]

To this, Stephen Hawking adds that even slight alterations in the life-enabling constants of fundamental physics in this hypothesized multiverse could "give rise to universes that, although they might be very beautiful, would contain no one able to wonder at that beauty.”[ii]

Whereas the weak version of the anthropic principle poses a logical conundrum, the strong version is essentially a statement of religious belief, namely that the universe has been tuned as it is because this was required—presumably by some divine creator—in order to establish conditions for human life (and/or perhaps those hairy-nosed wombats). An even stronger version has been called the “fixed anthropic principle,”[iii] namely that “intelligent information-processing must come into existence in the Universe, and, once it comes into existence, will never die out.” Martin Gardner dubbed it the “completely ridiculous anthropic principle” (CRAP). [iv]

There are some interesting non-sardonic responses to the anthropic assertion, whether in its weak, strong, or fixed version. Thus, maybe the various physical constants only appear to have been organized with carbon-based life in mind, whereas given the inherent nature of mass and energy, they are in fact simply the only values that they could possibly have. In short, are there any “free parameters” in physics? “What really interests me,” wrote Einstein, “is whether God had any choice in the creation of the world."[v] Note that Einstein explicitly denied belief in a traditional sky-god; instead, he used “god talk” as a scientific updating of Spinoza, referring to the manifold and complex characteristics of the physical universe. Whether “God had any choice” was his way of asking whether such things as the speed of light, the charge of the electron, proton, etc., are fixed or susceptible to alternatives.

The question, then, is whether reality as we know it is in some sense “pre-ordained,” but by the laws of physics rather than by some omni-benevolent and omnipotent creator. At present, we simply don’t know whether it would be equally possible, in some other universes, for entirely different laws of physics to obtain, or whether the different physical and energetic constants are independently derived by the action of a divine dial-twiddler, or, if and when physicists eventually come up with a grand unifying Theory of Everything, it may turn out that the various laws and physical constants are somehow bound together, such that the way the world works isn’t the result of a human-affirming providence but rather, the only way it could, given the nature of matter and energy.

Among the philosophical aspects of the anthropic principle (as distinct from its scientific components) is whether the issue is essentially a tautology: if something, anything, is observed about the universe, then if nothing else, that universe must consist of characteristics that permit the observer to exist. This, in turn, is reminiscent of Descartes’ cogito ergo sum: “I think, therefore I am.” But even more so, perhaps, of Ambrose Bierce’s cogito cogito ergo cogito sum (“I think I think, therefore I think I am”)[vi] which, Bierce playfully suggested, was about as close to truth as philosophy was likely to get.

Here is another truth: The universe is a big place and nearly all of it wouldn’t permit life; at least, not the kind of carbon-based, water-dependent life of which we partake. This, in turn, contributes to the temptation to conclude that our very existence is evidence for a beneficent designer. After all, If we were randomly placed in the universe, we would be dead almost instantly. But of course, we aren’t randomly located in the cosmos. Given the abundance of other possible locations, if we existed simply as a result of chance alone, we’d find ourselves (very briefly) somewhere in the very cold empty void of outer space. But we’re not the outcome of a purely random process: we happen to find ourselves on the third planet from the sun, a place that has sufficient oxygen, liquid water, moderate temperatures, and so forth—just what we need. Looking at ourselves this way, it isn’t merely coincidental that we occupy a planet that is suitable for life because we couldn’t possibly be living someplace that wasn’t.

By the same token, it isn’t amazing that the Earth isn’t a hot gas giant, because if it were, we wouldn’t be congratulating ourselves on the fact that we haven’t been melted or vaporized. Nor is it remarkable that no matter how tall or short a person may be, her legs are always precisely long enough to reach the ground. One might also turn things around and ask why the universe was “created” to be so inhospitable to life. After all, the universe contains stars, asteroids, comets, and galaxies beyond count that are very hot, very cold, highly radioactive, etc. and therefore devoid of anything identifiable as “life.”

As for the location of planet Earth within that universe, British cosmologist and astrophysicist Martin Rees puts it this way:

We find ourselves on a planet with an atmosphere, orbiting at a particular distance from its parent star, even though this is a very “special” atypical place. A randomly chosen location in space would be far from any star—indeed, it would be in the intergalactic void millions of light-years from the nearest galaxy.[vii]

Then there is another question, not necessarily deeper but, for some thinkers, more perplexing. More than three centuries ago, in The Principles of Nature and Grace, Based on Reason, Gottfried Leibnitz (1714) noted that “the first question which we have a right to ask will be, 'Why is there something rather than nothing?’” (Here, I’m especially fond of Sidney Morgenbesser’s reply to Leibnitz, that “If there were nothing you’d still be complaining!”) But there is something, and of course, if there weren’t, there wouldn’t be any opportunities for complaint.

David P. Barash is professor of psychology emeritus at the University of Washington. His most recent book relevant to this topic is Through a Glass Brightly: using science to see our species as we really are (2018, Oxford University Press). 


[i] Roger Penrose. 1989. The Emperor’s New Mind. London, UK: Oxford University Press

[ii] S. Hawking. 1990. A Brief History of Time. New York: Bantam

[iii] see, for example, Barrow John D. and Frank J. Tipler (1988). The Anthropic Cosmological Principle. New York: Oxford University Press.

[iv] M. Gardner. 1986. "WAP, SAP, PAP, and FAP," The New York Review of Books 23, No. 8 (May 8, 1986): 22–25

[v] quoted in A. Calaprice. 2000. The Expanded Quotable Einstein. Princeton: Princeton University Press.

[vi] A. Bierce. 2000. The Devil’s Dictionary. Athens, Ga: University of Georgia Press

[vii] Martin Rees. 1999. Just Six Numbers: the deep forces that shape the universe. New York: Basic Books.