Having Fun with ETI

ERNAN McMULLIN

Department of PhilosophyUniversity of Notre DameNotre Dame, IN46556 U.S.A.

A Review of Edward Regis (ed.), Extraterrestrials: Science and AlienIntelligence, Cambridge University Press, Cambridge, 1985, x + 278 pp.,hardcover $42.50; paperback $12.95.

Discussions of extraterrestrial intelligence (ETI) address three quite differ-ent clusters of questions, each cluster logically independent, to a largeextent, of the others. First is the existence and nature of ETI. What are thechances of life developing elsewhere in the universe? If life does developin a given location, how likely is it over time to take on intelligent forms?To what degree would they resemble us? The second set of questionsfocusses on communication. Suppose ETI does exist, could it communi-cate with us? How could we detect such communication? What would theconsequences of it be for the human race? The third takes the possibilityof ETI as an occasion for inquiring into the significance of humaninstitutions. Asking whether alien intelligences would develop science aswe know it or would be governed by ethical norms similar to ours is aroundabout way of asking how universal a claim we can make for theprinciples of our science or of our ethics. Inquiring into the likely relation-ships between ETI and God is a lively way of getting at the various claimsto uniqueness that seem to be built into Western religion.

The first cluster of questions pertain mainly to the natural sciences,though requiring a rather freer use of imagination than the sciencesordinarily endorse. The second belongs mainly to the social sciences,especially anthropology, as well as to philosophy, and to the new sciencesof artificial intelligence. The third is the domain of philosophy andtheology, though perhaps most effectively treated by science-fictionwriters (Ursula Le Guin and Frank Herbert come to mind).

In a new collection of essays, some already in print, most writtenspecially for the occasion, Edward Regis has provided a sample of thediversity of answers currently given to each of the three sets of questions.One might expect the editor of an anthology such as this one to be anenthusiastic supporter of the claims for ETI. But Regis takes a quitenegative line on the devoting of large sums of money to the systematic

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screening of incoming radiation for clues to the presence of intelligence"out there". In his own essay, he argues that if the search is negativenothing will have been learnt; if it is positive, we would be unlikely tobenefit from it. This may be a little extreme, but as a corrective for thekind of hyperbole to which Sagan and others have accustomed us, it isprobably needed. (For an excellent account of the way in which hyperboleabout the chances of life on Mars shaped NASA's Viking Project in the1970's, see Cooper, 1980.)

In the opening essay of the collection, Lewis Beck wryly notes that ifhis paper were not to have been a Presidential Address (to the EasternDivision of the American Philosophical Association), he would be unlikelyto obtain a hearing among philosophers. (I remember very well sitting onthe floor at the back of that crowded room in 1971 and rejoicing in hiscourageous choice of topic; I also remember that it seemed "unphilosoph-ical" to many of those present, more accustomed to the minutiae ofanalysis). Yet the topic of ETI has been discussed by philosophers sinceancient Greek times, Beck reminds us, the Roman writers Lucretius andPlutarch having given memorable expression to the belief in a vastplurality of inhabited worlds. (The long and intricate course of the earlierdiscussions of ETI are chronicled in two masterful recent works: Dick,1982; Crowe, 1986.)

The successes of the theory of evolution, both biological and astrophys-ical, and the enormous increase in the reach of our telescopes, haveencouraged many to conclude that there must be a lot of ETI out there,even though it has not made its presence known to us yet in any way. Beckis oddly ambivalent. He argues (rightly, to my mind) that the sciences canonly provide us with conjectures about the necessary conditions for life;they cannot possibly (at the present time, at least) provide us with thesufficient conditions, and therefore with the probability of the occurrenceof life elsewhere. He believes that the premises underlying the search formessages in the electromagnetic spectrum are unacceptably anthropomor-phic; furthermore, simultaneously existing civilizations would be veryunlikely to possess compatible technologies of communication at the samemoment as we do. He speculates that the recent penchant for givingconfident estimates of the (large) numbers of inhabited planets in ourgalaxy may be prompted on the one hand by the need to justify largeexpenditures on the part of the U.S. and Soviet space programs, and onthe other hand by quasi-religious hopes of help from beings mightier thanourselves. But he ends on an unexpectedly positive note, recommendingthat the search for ETI messages be continued on a worldwide basis,despite the reservations he had earlier expressed about this project.

Ernst Mayr and Frank Tipler both remark that most of the promotersof the ETI thesis are physical scientists who are used to thinking determin-istically in terms of predictive theories. The leading evolutionary biologists

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are almost all openly skeptical about the likelihood of ETI; they are morefully aware than their physicist colleagues of how opportunistic evolu-tionary developments on earth have been. The neo-Darwinian schema,though explanatory, ought not (they say) be used predictively. Mayr goeson to reverse the account given by defenders of ETI of the "inevitability"of the development of intelligence under the operation of natural selec-tion. It took three billion years for life on earth to make the transitionfrom prokaryotes to eukaryotes; of the 40 or so original phyla of animals,only one (the chordates) eventually gave rise to intelligent life; of all thevertebrates, only one gave rise to amphibians; of all the amphibians, onlyone to reptiles; of all the reptiles, only two gave rise to life that could at allbe classified as intelligent (birds, mammals); only one of the many ordersof mammals gave rise to a superior form of intelligent life (the primates).And so on, down to man. His conclusion is that intelligence, far frombeing a necessary outcome of the evolutionary story, is rather an "incred-ible improbability", since of the billion or more species produced alongthe way, only one is fully intelligent. Eyes have developed independentlyin more than forty different kinds of animals; no similar convergentevolution appears to favor intelligence. I am not entirely convinced by thisargument. Any non-deterministic sequence will look like this in retrospect;the advent of humanoid intelligence has been so recent and so abrupt thatother lines have had no opportunity to develop similarly intelligentspecies, and now probably never will.

Frank Tipler argues that ETI does not exist; if it did, it would neces-sarily develop the technology for interstellar travel and would havealready made its appearance here. He claims that a "majority of computerexperts" believe that within a century we will be able to make "vonNeumann machines", "self-reproducing universal constructors" that couldbe launched to other stellar systems and would there be set to constructcopies of themselves to be launched to yet further systems. Since wewould need to construct only the first set of machines, leaving all the restto them, "the exploration of the Galaxy would cost about three billiondollars" and "colonization" of the entire Galaxy would take only fourmillion years. (This is one of the major themes of the recent comprehen-sive and highly controversial work, Tipter and Barrow, 1986.)

The fundamental thesis here is, to my mind, entirely fallacious. I do notknow of any computer experts who believe that within a century suchmachines will be buildable. What von Neumann showed was only that it istheoretically possible that a machine might be constructed which could beprogrammed to make a copy of itself, given the requisite materials. Such amachine would obviously not suffice for the task that a "Tipler machine"would face when it arrived in a new planetary system. In their essay, CarlSagan and William Newman characterize Tipler's views as "solipsist",calling on a principle of "mediocrity" that denies we could be in any way

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unique; this seems just as fallacious as Tipler's principle of necessary"colonial" expansion. They go on to suggest some reasons why ETI wouldnot have shown itself here even if it is relatively abundantly distributed,and argue that Tipler's model of galactic colonization by machines doesnot fit what we know about colonization from human history. It is hard toknow what to make of speculative discourse of this sort, armed as it iswith an abundance of tables and charts, and issuing in precise figures forsuch things as the time for a "colonization wave" to cross our Galaxy.

The two most interesting contributions to the collection, to my mind,take the possible existence of ETI as their starting point, but areconcerned much more with the affairs of earth. To ask whether the naturalsciences or the ethics of an extraterrestrial civilization would resemble ourown is an oblique way of posing the philosophical question as to what thetitle of our own sciences and ethics to objectivity may be. To hold thattheir science or their ethics might be quite different from ours necessarilylimits the claim that our science or our ethics is rooted in "the nature ofthings". To put it this way could be misleading since (as yet, at least) weknow nothing of extraterrestrial achievements in either area, so we canmake no inferences from them. The introduction of the ETI dimensioninto the discussion is only an imaginative device to enable one to build acase for or against the objectivity (universality, a priori status, etc.) of ourscientific theories or our ethical norms. As might be expected, the realist(using the most convenient label from contemporary philosophical debate)will be likely to infer that the sciences, and (perhaps) basic ethics arecosmically invariant; the anti-realist will infer that they are likely to varyfrom one locus of intelligence to another.

Making skillful use of broadly Kuhnian arguments, Nicholas Rescherconcludes that extraterrestrial science would be most unlikely to resembleours in any way, even though "there is only one universe, and its laws, asbest we can tell, are everywhere the same" (p. 90). Though our ownscience may be said to "progress" in the sense of strengthening the warrantfor its claims, it is not evolving towards a unique and comprehensivestructure, equally accessible to the intelligences of other worlds. Thefundamental categories of which Kant made so much (spatiality, tempo-rality, causality) are not "necessary features of intelligence as such, butevolved cognitive adaptations to particular contingently-constituted waysof emplacement in, and interaction with, nature" (p. 89). Though aliencivilizations would have to accommodate to the same universe as we do,their "world" would be quite different, "since they live in a significantlydifferent environment and come equipped with significantly differentresources" (p. 93). Their problems would thus be quite different. Tosuppose that they would converge on the same sorts of explanatorystructures as ours is no more than "an implausible bit of metaphysics", the"myth of the God's eye view" (p. 87).

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Their resources would be different (i.e. our resources are contingent).Their mathematics might be quite unlike ours. (Marvin Minsky in anotheressay in the collection takes the opposite point of view, that their mathe-matics and even their grammatical forms would have to resemble ours; atcrucial moments, however, he falls back on expressions like 'my guess is'and 'I suspect that'). Their sensory organs would undoubtedly differ fromours. They would focus on different aspects of the universe. Theirconceptual structures would not be like ours; we would have no moreaccess to them than to those of the sciences of our own distant future.Even on earth, different civilizations have in the past produced quitedifferent natural sciences. If the medicine of the ancient Hindus coulddiffer so much from that of the ancient Greeks, why should we supposeany greater similarity between modern Western science and the productsof ETI? Would it not be far less? Modern medicine has abandoned the"humors" so central to Galen's theories; the Galenic physician could makenothing whatever of bacteria or DNA. It is anthropomorphic to supposethat anywhere else intelligence could be engaged in our kind of science atall; hence, the prospect that ETI might carry science ("our sort ofscience") further than ourselves is quite remote (p. 114).

Though these considerations are obviously not without force, Rescher'sconclusions are, at the very least, overstated. Here are (rather summarily)some counter-considerations. (1) There is no reason to think that therecould be alternative arithmetics. (2) The entire course of natural sciencesince the 17th century has been to replace the sensory modalities withinstrument-readings, precisely because of the contingency and incomplete-ness of our sensory apparatus that Rescher makes so much of. (3) He iswilling to allow that a project broadly like ours in terms of its goals(prediction, control, explanation...) could develop elsewhere; this is whatenables us to speak of it as "science" in the first place (p. 84). But we havediscovered, over the long and tortuous course of Western science, aparticular way of linking these goals by means of certain techniques so asto maximize the achievement of the goals themselves. The same discoverycould be made elsewhere. The products of this are theoretical structures,like the one on which the discussions of ETI itself are based: a cosmolog-ical structure of galaxies, stars, and planets, with particular chemicalconstitutions and evolutionary histories. There is every reason to attributea fair degree of reliability to the broad outlines of this picture. To say that"we are prisoners of the thought-world that our biological and social andintellectual heritage affords us" (p. 94), to suppose that a cosmologyconstructed by distant intelligences should be expected to come up with aquite different theoretical structure, is to underestimate the power of theretroductive modes of theory-formation and assessment that have gradu-ally been developed in recent centuries. This is obviously not to say thatthe course of an ETI cosmology would be the same as, or even very

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similar to, ours. But their products, if their goals involved successfulprediction, could not over the long haul be entirely different. (4) It will notdo to cite the abandonment of Galenic humors as grounds for supposingthat the modern bacterial theories of infection might likewise proveephemeral. The infrastructures of proof supporting those latter theoriesare of a different kind, and give us ample reason to suppose that futuretheories of infection will not be radically dissimilar. Nevertheless,Rescher's imaginative exercise is of value because it reminds us that theconceptual structures of even our most successful sciences may have morecontingency built into them than people are wont to admit.

Michael Ruse performs a similar exercise, this time involving bothscience and ethics, and comes up with a rather different result. To thetitle-question of his essay, "Is rape wrong on Andromeda?", he gives a(hesitantly) positive answer. He makes his stance in regard to ETI clear: "Iam quite indifferent as to whether or not there is life elsewhere in theuniverse" (p. 45). Why, then, write about it? In order, he replies, "to throwinteresting light on ourselves" (p. 46). His starting-point is a premise thatwould seem very dubious in the light of recent quantum mechanics: "As adeterminist and a mechanist, I certainly believe that, given the identicalcombination of chemicals and conditions as prevailed here on earth, lifewould necessarily appear in exactly the same way" (p. 46). His strategy isto ask what would happen on a planet on which stable primitive organismssomehow made their appearance. Provided there are slight differencesbetween them, natural selection will necessarily occur. "Moreover, thisnatural selection will lead to evolution. That is to say, one will get anongoing change in the organisms on the planet" (p. 48). The main featureof this change will be adaptations, "characteristics which help eachorganism individually". There is, however, "no reason to think" that thiswould involve a progression towards intelligence, nor even the develop-ment of sexuality and speciation. All we can say is that "we might possiblyhave the evolution of more sophisticated organisms on our hypotheticalplanet, and these could even reach the realm of intelligence" (p. 50).(Since it has in fact happened once, this seems a pretty safe bet!).

Suppose intelligent organisms do appear. Their senses may be quiteunlike ours. Whether they are conscious or not does not matter (p. 53). (Iam not so sure). But what of their science? Since there is a common worldout there where the laws of arithmetic and of mechanics hold universally,natural selection will see to it that their science will have something incommon with ours. ("I have no reason to doubt that really 2 + 2 doesequal 4. Why? Because I have no reason to, that's why", p. 55). "The basicpremises of logic, of mathematics, of causality" will be held in commonbecause holding them will give an adaptive advantage. Animals withdifferent sorts of sense-organs respond, as we know, in a consistent way tothe world; our own different senses also present the world in a consistent

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way. One can conclude, then, that "reality is the same for all"; hence, "onecan say confidently that extraterrestrial beings will share with us certainfundamental underlying principles" (p. 58). "To say that our powers arelimited and that we can say no more is just to say that it is inconceivablethat ultimate reality is other than we think it is" (p. 59). (But surely it is tosay much less than that?). In short, "we share our powers of comprehen-sion [with ETI] because we are both products of evolution".

How about ethics? Ruse suggests that a similar argument can be used toshow the universality of such fundamental ethical principles as thePrinciple of Greatest Happiness or the Categorical Imperative. But thisdoes not run so simply. "Our sense of morality is an adaptation. Wesurvive and reproduce more efficiently with it than without it" (p. 62).Those who acted immorally were at a disadvantage in society, and so"they failed to survive and reproduce as efficiently as those with a sense ofmorality". Altruistic behavior towards one's kin benefits one's own geneticlegacy. Altruistic behavior towards others tends to be reciprocated; those"who are helped by others are in a better position to survive andreproduce than those who are not". It is not a matter of acting inconscious self-interest; in fact, it will be more effective in eliciting favorfrom others if it seems genuinely altruistic, i.e. carried out with no expecta-tion of return. "I cannot conceive", Ruse concludes, what an extrater-restrial morality could be if it were not to resemble human morality at themost basic level. And if it is inconceivable, "it is certainly not something inwhich it is reasonable to believe" (p. 68). (Rescher would have somethingto say about this close tie between conceivability and possibility).

Sexual difference is quite likely to develop among extraterrestrials,Ruse goes on, because it brings enormous adaptive advantage. Behavioranalogous to rape, for instance, is not unusual in certain animal species;males who behave in this way may indeed be "more likely to reproducethan otherwise". But among humans, there is a universal belief that rape iswrong. "Because humans take so long to mature, males co-operate inchild-rearing" (p. 67). Hence, they want to minimize the chance that thechild they are rearing is not their own. Maintaining the belief that rape iswrong is one way to ensure this. (Ruse adds, however: "I am not saying wethink rape is wrong simply because males might have to raise the childrenof others. I am looking for biological reasons why we might feel sostrongly about it"). "There could well be" similarities between the ter-restrial and the extraterrestrial in regard to the attitudes towards suchbehavior. (Ruse's logical connectives in this section are all pretty weak:"My suspicion is . . .", "I see no reason why. . .", "my own hunch is . . .", "Iwould hazard a guess that . .", "But, perhaps naively, I suspect that . .").

As with Rescher, I have to be content with merely listing some of themore obvious questions this approach raises. There is a fundamentalobjection to this use of the natural-selection line of argument. In the

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Darwinian case, the offspring inherit the favored disposition, the one thatgives the adaptive advantage. To say that holding a particular moral beliefgives an agent an advantage in terms of differential reproduction saysnothing about the beliefs of the agent's offspring. Beliefs are not inherited.If, instead, one speaks of modes of behavior, propensity to such repro-ductively advantageous behavior can be instinctive, and may in that casebe inheritable. But then it is precisely not morally-guided behavior.

There is a very important difference between the argument in regard toextraterrestrial science and that in regard to extraterrestrial ethics. Tobelieve that 2 + 2 = 4 is biologically advantageous only if 2 + 2 = 4. Butcan one say that to believe rape is wrong is biologically advantageous onlyif rape is wrong? It does not seem so. Much depends, of course, on whatis meant by 'wrong' here. Unless one equates it precisely with 'biologicallydisadvantageous', making the claim above a truism, the inference will notwork. It is not the wrongness of the action that makes it biologicallydisadvantageous. Rather, it is the belief that it is wrong (whether it iswrong or not) that is, or at least may be, reproductively effective becauseit tends to prevent the action from occurring. The case of arithmetic ornatural science is not parallel. The agent's belief in the laws of mechanicswill be of adaptive advantage only (at best) if the laws are correct.

Ruse is aware of the difficulties inherent in his line of argument. Whenhe says that our moral sense gives us a biological advantage, he quicklyadds: "This is not in any way to say that that which is evolved is morallygood. In other words, this is not some form of crude social Darwinism",endorsing the "process" or the "products" of natural selection as "moralgoods" (p. 62). And again, "I am trying here not to slip into some sort ofnaturalistic fallacy, arguing that morality is simply a function of evolution,and that which has evolved is that which is good" (p. 71). But if this is notwhat he is arguing, what does it mean to claim that our possession of amoral sense which leads us to endorse or restrain specific kinds of actioncan be explained in evolutionary terms? It does not mean, apparently, thatthese kinds of action are themselves claimed to be good or evil inconsequence of their biological effects. What it seems to mean is that anevolutionary explanation is to be given for the fact that people believe (or"feel strongly") that a particular course of action is right or wrong. Toexplain the origin of a belief that an action is right or wrong is not (asRuse sees) to endorse the action one way or the other. It is not to proposean ethics. The evolutionary explanation is irrelevant to ethics as such.

Ruse appears at times to sanction this weakening of the claim he ismaking, when he calls himself a "Humean", concerned about explainingwhy we believe certain things rather than in warranting those things astrue or moral (pp. 60, 65). We believe them, then, because we are causedto believe them in a certain way. Leaving aside the deficiencies in theHumean account of cause, here once again there is a crucial difference

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between the contexts of natural science and of ethics. A necessary condi-tion for our believing in a causal relationship between fire and burn-injuryis that these, in fact, should have been constantly conjoined until now.There is no similar constraint in the case of the belief that rape is wrong.Ruse characterizes the "Humean" here as holding that "morality does notcorrespond to an external law" (p. 65). What does it correspond with? Ifmoral action is to be anything more than instinctive behavior, we need toknow what the source of its imperative is.

Ruse gives one hint of an intuitionist ethics, in which evolution wouldbe responsible for developing in us a moral sense. This sense, oncedeveloped, would in its own right have the ability to discern what is reallyright and wrong. But this would need to be filled in. Until then, a moreappropriate title for his essay might be: "Why Andromedans might believethat rape is wrong"!

REFERENCES

Cooper, H.: 1980, The Search For Life on Mars, Holt, New York.Crowe, M. J.: 1986, The Extraterrestrial Life Debate 1750-1900: From Kant to Lowell,

Cambridge University Press, Cambridge.Dick, S.: 1982, Plurality of Worlds: The Origins of the Extraterrestrial Life Debate from

Democritus to Kant, Cambridge University Press, Cambridge.Tipler, F. J. and Barrow J.: 1986, The Anthropic Cosmological Principle, Clarendon Press,

Oxford.

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