When scientists extrapolate from empirical data to probabilistic speculations, I don’t consider that they have any more authority than laypeople. When I read about theories that deduce from the probability that the “laws of nature” are such as to allow for the universe as it is that there must be n other universes out there that we know nothing about, I consider this about as reasonable as calculating the number of angels who can dance on the head of a pin. How does one make a probability space with only one universe to go on? How does one know what parameters to vary? The universe is not “mathematical”; we invented mathematics to allow us to manipulate measurements of the universe, but the universe doesn’t “obey” mathematical “laws.”
But similar speculations carry a real payoff in the far more interesting dilemma posed by the possible existence of extraterrestrial life. It’s hard to say even what it means to speak of “other universes” with which we have no means of communication, but whether or not life and/or sign-users exist elsewhere in our own universe is a question whose answer, assuming one can eventually be provided, will surely be of great consequence.
It seems that virtually every article on astronomy that I read in Scientific American or Science News—two science periodicals for the educated layperson—is focused on the search for extraterrestrial life. The current astronomical obsession with exoplanets seems to have little other raison d’être, and the April 30, 2016 issue of the second of these journals made “In Search of Aliens” its cover topic. In one of the articles (“Will we know ET when we see it?” p 28-31), the author quotes one investigator as saying, “I think I would be surprised now if they don’t find life on Mars” (30), another as predicting that “there are several planets or moons [in our solar system] with life on them” (31), and a third as affirming that “I think life is a cosmic imperative” (31). Thus it seems to be tacitly assumed that it suffices (Uniformity Principle dixit) for another planet to have anything like earth-like conditions for the existence of life there to be all but certain, which doesn’t exclude seeking life on the others. And when we don’t find any evidence of life, we are told that perhaps we have already seen it but haven’t recognized it because it is so unlike ours.
One thing I have noticed, however, is that, unlike what we used to hear a decade or two ago, no one seems to be holding their breath waiting for a signal from intelligent life. Now if the Uniformity Principle makes it all but certain that life exists on some, many, or most of these exoplanets, then given the billions or perhaps trillions of these in the universe, how could it be that no other intelligent life-forms exist that have either voluntarily or not, broadcast their existence? If life is driven by the inexorable force of natural selection to evolve ever more advanced feedback and control systems, then if there is life “everywhere” how can it be possible that it has progressed nowhere else beyond the monocellular? And one thing leading to another, once sign-systems are invented/discovered, one would assume that the rest of human development, however marvelous, is reasonably likely. Even if we assume that any such “intelligent” creatures are bound to invent weapons too powerful to control and eventually destroy themselves, a society can’t reach the point where it can assure its own self-destruction until it has already attained a high level of technological prowess. So that even in the more pessimistic apocalyptic scenarios that seem a little bit more probable every day, there should in most cases be enough of a gap between acquiring signaling technology that we earthlings could observe and self-annihilation so that one of the millions (thousands? dozens?) of intelligent life-forms out there would make itself known to us.
Our solar system is not one of the older ones, so the inhabitants of many exoplanets would have had billions of years longer than we to develop symbolic intelligence. And given that our broadcasting instruments are already pretty effective and that the emitters would have a billion years or more on us, one would think that even if most of them were reluctant to send out detectable messages, at least one would feel safe in doing so; and in any case, how would they maintain silence if they themselves wanted to probe the universe? All this is without speaking of the more far-fetched scenarios of “visitors from outer space” via time-warps and the like. Is the silence of the universe concerning intelligent life not a strong indication that there is no elementary life elsewhere either? Yet this argument never seems to come up when funds are being requested for the nth probe or space telescope to seek for and explore exoplanets.(I apologize to science fiction readers who have no doubt heard these rather obvious arguments in a more elegant form. But one never does see them presented in the popular science journals I read.)
My personal opinion, for what it’s worth, is that in the absence of evidence, and so far there has been absolutely none, we must assume that life exists only on Earth. Evidence of the “conditions for life,” such as “organic” molecules on meteors or formerly existing water on Mars, is not evidence at all; the uniformity principle assures us, if not of life itself, then at least that the “conditions for life” in the broad sense exist in billions of places. And just as speculating about the probability that the “laws of nature” are such as permit life or humanity (the “anthropic principle”) is totally gratuitous, so is speaking of the probability that life exists on a given planet, given that we don’t know exactly how it emerged on ours let alone how to calculate the probability of the concurrence of the necessary contributing factors.
At the very least, we do have Darwinian theory that allows us to explain the passage from elementary to more complex creatures, and, when one day GA is given its due as A New Way of Thinking, from the latter to the human. But we have only vague speculations about the origin of life itself. Although disappointed by his pointed neglect of language, and therefore of the specifically human, I was impressed by Terrence Deacon’s model of life-emergence in Incomplete Nature (Norton, 2012)—please see Chronicle 490. Deacon’s model combines two crystal-like replicants: a freely self-replicating “interior” and a chain-like self-accreting “exterior” that would serve as a protective membrane allowing the interior elements access to the materials of further replication in a protected environment. But there is no question of attempting to gauge the probability of such a development.
As with “global warming” aka “climate change,” I would feel more comfortable examining the evidence for extraterrestrial life if it were not so obvious that the “progressive” intellectual class attaches a positive moral valence to one side of the question. Just as climate changers cast the planet as the ultimate victim of “capitalist greed,” so ET-seekers see our pride in our apparent uniqueness as an illusion on the level of believing that the earth is fixed at the center of the universe. But we cannot know whether the familiar victimary/oikophobic paradigm applies until we indeed know what probabilities are in play.
As a believer in firstness and, if not in “the West,” then in the lesson it has bequeathed to the rest of the world, which may have become by now more able to build on it than we, my prejudices are contrary to those of the vast majority of the intelligentsia, who although competitive in their own sphere, find it immoral to accept in principle that some things/species/cultures/talents/societies/are superior to others. I have no quarrel with the uniformity principle, but unique events do occur, for all events are unique, and it seems to me more in accord with Ockham’s razor that if the evidence shows no sign of life anywhere but here, then we should assume this to be the case universally until proven otherwise. This should not prevent the search for extraterrestrial life as a disconfirmation of this hypothesis; falsification is what science is all about. But we should be skeptical rather than confident of finding life elsewhere, if only to preserve as long as possible—and possibly “forever”—our pride in being the only sign-using creatures in the universe—and the only ones who could have conceived the originary hypothesis.
And if the social scientists tasked with studying human origins are unable to give credence to this hypothesis rather than seeking to explain the emergence of the human through all kinds of peripheral activities—recent attempts I have seen included collective song, the disgust-reaction (thanks to Peter Goldman for this one), and the mental functions developed in flint-knapping—is this too not the result of the very same reluctance to accept the necessity of firstness, of a unique event, as opposed to a gradual process that painlessly derives the human from the animal? In the thirty-five years since The Origin of Language came out in 1981, at least we have stopped trying to teach human language to apes.