Many Worlds: Theological Issues

Metaviews 103. 2000.12.28. Approximately 3440 words.

Below is another installment from the book Many Worlds: The NewUniverse, Extraterrestrial Life & the Theological Implicationsedited by Steven Dick. This installment, titled Life andIntelligence Far from Earth: Formulating Theological Issues iswritten by Ernan McMullin.

The OπHara Professor of Philosophy, now emeritus, at the Universityof Notre Dame, Ernan McMullin is an internationally respectedphilosopher of science who has written and lectured extensively onsubjects ranging from the relationship between cosmology andtheology, to the role of values in understanding science, to theimpact of Darwinism on Western religious thought. A graduate ofMaynooth College in Ireland, where he received an undergraduatedegree in physics and a bachelor of divinity degree in theology, hewent on to study theoretical physics at the Dublin Institute forAdvanced Studies and earned a Ph.D. in philosophy at the Universityof Louvain in 1954. Joining the Notre Dame faculty as an assistantprofessor of philosophy that same year, he was named to the JohnCardinal OπHara Chair in 1984 and chaired the department from 1965 to1972. He has been a visiting professor at the University ofMinnesota, the University of Cape Town, the University of Californiaat Los Angeles, Princeton, and Yale, a Phi Beta Kappa NationalLecturer, and a Cardinal Mercier Lecturer at the (Flemish) Universityof Leuven. In addition, he has served as president of the AmericanCatholic Philosophical Association, the Metaphysical Society ofAmerica, the Philosophy of Science Association, and the WesternDivision of the American Philosophical Association, as chair of theHistory and Philosophy of Science Section of the American Associationfor the Advancement of Science, as a member of the executivecommittees of the History of Science Society, the Council forPhilosophical Studies, and the Society of Christian Philosophers, andas a member of numerous scholarly and scientific committees,congresses, and panels. A fellow of the American Academy of Arts andSciences, the International Academy of the History of Science, andthe American Association for the Advancement of Science, he holdshonorary degrees from Maynooth, the National University of Ireland,and Loyola University (Chicago). A member of many editorial boards,Dr. McMullin is the author of numerous scholarly articles and ninemajor books and the editor of a series of monographs on logic. Hislatest volume is The Inference That Makes Science, published in 1992.He is working on a study of rationality, realism, and the growth ofknowledge.

McMullinπs essay considers the implications of theoretical and futureempirical probability/possibility of Extraterrestrial Life (ETL) andExtraterrestrial Intelligence (ETI) to the particularity of the Humanand Earth-centered cosmologies of the Western theistic traditions.The plurality of worlds in the universe has long been a topic fortheological debate, particularly in Christianity, going back at leastas far as the Middle Ages. McMullin offers an illuminating survey ofdifferent theological interpretations of doctrines like ≥Original≤Sin, the Body and Soul, and the Incarnation in light of thechallenges presented by the possible plurality of worlds.

This posting is part of a series of postings from the MANY WORLDSbook, edited by Steven Dick, 2000 (see Metaviews 092, 095, 097, 101).If you like what you read, the book is available for purchase onlineat.

-- Billy Grassie

Ernan McMullin, ≥Life and Intelligence Far from Earth: FormulatingTheological Issues≤ in MANY WORLDS, edited by Steven Dick,Philadelphia: Templeton Press, 2000 (pp. 151-175).

Chapter Excerpt:

Plurality of Worlds

In popular discussions of extraterrestrial intelligence, it tends tobe assumed that the discovery of such intelligence would pose newproblems, new challenges, for religious believers. But as historiansof science have recently reminded us, the notion that we shouldexpect to find such intelligence came, in significant part, fromChristian theologians in the first place.9 The revival ofAristotelian natural philosophy in the Latin West in the thirteenthcentury led to a rupture of serious proportions between Aristotelianphilosophers (many of them also theologians) and theologians of amore traditional persuasion. One of the main issues that divided themwas the status of propositions in natural philosophy. According toAristotle, scientific demonstration should proceed deductively frompropositions perceived to be true, indeed necessarily true, in theirown right, after the manner of geometrical axioms. Theologians werequick to point out that if Aristotle's cosmology be allowed thisstatus, it would imply that the general structure of the world couldnot be other than it is, thus compromising the key Christian doctrineof Divine freedom. The theology of creation deriving from Augustinemaintained that the Creator was in no way constrained in fashioningthe sort of universe in which we find ourselves.

One of the test cases between the two sides of this debate waswhether there could be a plurality of worlds. For the Aristotelians,this was impossible. Were there to be another world, it would stillhave to be of the same general sort as this one; a simple analysis ofnatural motion would then show (as Aristotle argues in two densechapters of his De Caelo, I, 8-9) that it would reduce necessarily tothe world we already have. To many theologians of that day, thisseemed an implicit denial of Divine omnipotence. And so thepossibility of a plurality of worlds became a rallying point forthose who were alarmed at the necessitarian tendencies of the newnatural philosophy. Despite the efforts of Thomas Aquinas to mediatethe quarrel, the Aristotelian position was condemned in 1277 by acouncil of the bishops of France, thus giving an official status tothe doctrine of the possible plurality of worlds.

What the defenders of this doctrine maintained was no more than thepossibility of other worlds, that is, God's freedom to create suchworlds if God desired to do so. They did not argue that God has, infact, done so; they would have seen no reason to suppose that aplurality of worlds actually existed. But they had not only openedthe way to such a supposition, they had given it broad theologicalsanction.

With the revival of Neoplatonic ideas in the Renaissance, a furtherstep was taken, the introduction of what later writers would call aprinciple of plenitude. The principle was of philosophical, ratherthan of specifically biblical, origin. But it rested on a particularview of the nature of God, one that had some resonance with thetraditional Augustinian doctrine of the omnipotence of the Creator,so it might also be called theological in a somewhat broader sense.The principle lays down that a Creator such as is envisioned in theChristian tradition must bring to be all that is possible, out of thefullness of the Divine power and goodness. It is the presumed natureof God that leads to the expectation that a plurality of inhabitedworlds is not only possible, but in some sense necessary.10

Developments in astronomy in the seventeenth century gave freshimpetus to these ideas, not only of an actual plurality of worlds,but of worlds inhabited perhaps by living and even intelligentagents. As historians have shown in some detail, the likelihood ofETI became almost a commonplace in Western Europe in the eighteenthand nineteenth centuries.11 What is especially striking about thisdevelopment is the support that this idea of ETI received amongChristian thinkers of that time. They were aware of the difficultquestions that the reality of ETI would pose for Christians. But formost of them, this potential negative was evidently overcome by theirconviction that the presence of ETI in many parts of the universe waswhat one should expect from an omnipotent Creator, whose power andgoodness would in this way be made manifest. As telescopic evidencefor the vast scale of the universe mounted, it seemed more and morelikely (it was argued) that the Creator would not have left thesevast spaces empty of the only sort of life that could freely offerhomage to the One on whom this mighty frame depends for its verybeing.

When Christians are asked today what response religious believersought to make to the growing conviction that the operations ofevolution on a cosmic scale would almost necessarily eventuate inlife and intelligence in a great number of locations, their firstanswer might well be that such a plenitude is just what one shouldhave expected, given the premium that the Genesis account of originsalready sets on the gifts that allow human beings to be regarded assomehow imaging their Creator. It is in these gifts and theirpossessors that the story of the Creation in Genesis seems to findits deepest meaning. Would it not seem, then, that as the dimensionsof the Creation prove incomparably greater than those of the centralEarth of early tradition, the bestowal of that image could hardly berestricted to that single locus?

Not everyone saw it in that way. Indeed, some critics turned mattersaround to make the plurality of worlds an argument againstChristianity. Notable among these was Thomas Paine who in The Age ofReason (1793) argued that the two beliefs cannot be held together inthe same mind; and he who thinks that he believes in both has thoughtbut little of either.12 Paine took for granted that the astronomicalscience of his day had already established the plurality of worlds.Telescopes showed a vast number of fixed stars; the probabilitytherefore is that each of those fixed stars is also a sun, roundwhich another system of worlds or planets, though too remote from usto discover, performs its revolutions. . . . 13 And so: thesolitary idea of a solitary world . . . in the immense ocean ofspace, gives place to the cheerful idea of a society of worlds, sohappily contrived as to administer, even by their motion, instructionto man.14 And since the Creator has filled our own world with lifeat every level of size and complexity, we should expect that the samewould be true of that vaster universe; the immensity of space cannotsimply be a naked void lying in eternal waste.15 Although there areovertones here of the principle of plenitude, Paine's argument hingesnot so much on the nature of God as on the belief that the Creatororganized the structure of the universe in the most advantageousmanner for the benefit of man as well as for the humanlikeinhabitants of the multitude of other words.16

Paine goes on to assail Christian belief, to a deist like himself alamentable aberration. Christians, he says, are faced with a dilemma:they must either believe that the Almighty, who had millions ofworlds equally dependent on his protection, should quit the care ofall the rest and come to die in our world because, they say, one manand one woman had eaten an apple, or else suppose that every worldin the boundless creation, had an Eve, an apple, a serpent, and aRedeemer. In this latter case, the person who is irreverentlycalled the Son of God, and sometimes God himself, would have nothingelse to do than to travel from world to world, in an endlesssuccession of death, with scarcely a momentary interval of life.17

Laying aside the element of conscious caricature in these passages,one can easily enough discern the sort of challenge that Paine isposing to believers in the Incarnation, that is, in God's taking onhuman nature in a particular individual who grew up long ago inGalilee. His objection is posed to Christians only, not to Jews orMuslims who could, without much of a stretch it would seem, allowthat intelligent peoples elsewhere in our galaxy might be granted bya magnanimous Creator their own Moses, their own Mohammed. How, Paineasks, are believers in the Incarnation to adjust to a new cosmologyin which the created universe no longer centers on the Earth and inwhich humanity is scattered across myriad planets? It was easier toaccept the idea of God's becoming man when humans and their abodeboth held a unique place in the universe. But is it any longercredible in the light of the new questions that the plurality ofinhabited worlds poses?

Paine's challenge has been repeated many times since his day,recently again by Roland Puccetti in his Persons: A Study of PossibleMoral Agents in the Universe.18 Puccetti draws on P. F. Strawson'sinfluential analysis of the notion of a person19 to argue thatpersons must be corporeal and hence cannot be in more than one placeat the same time; they must be capable of moral agency and hence mustbe able to experience sensations and emotions as only corporealbeings can. This, of course, would mean that the notion of a personcould not be applied to God, not at least in the traditionalunderstanding of God as a spiritual being. (This would be ironic inlight of the fact that the term person in its Latin version personawas first used, in something of its modern sense, of God not ofcorporeal beings, when theologians of the early Christian centuriesattempted to illuminate the difficult doctrine of the Trinity.)

In a final chapter, Puccetti asks (somewhat illogically it mightseem), But suppose we do apply the term person to Christ, what arewe to make of the doctrine of the Incarnation, given that we are nowcertain on scientific grounds (according to him, at least) thatcivilizations have developed frequently elsewhere in our galaxy? (Heeven suggests that 1018 might be the best current estimate for thenumber of ETI sites in the known galaxies.20) It would be impossibleeven for God, he argues, to become incarnate in so many locations inthe time available, given that a person cannot be present in morethan one place at once. Alternatively, if defenders of Christianfaith were to hold that God became incarnate on Earth only, theywould be faced with the objection that the inhabitants of otherplanets would be unlikely ever to learn of it. How, then, would theybe saved? Since the Incarnation is central to Christian belief,Puccetti concludes that the discovery of this vast plurality ofinhabited worlds undermines the Christian religion decisively.

His argument rests on some shaky presuppositions.21 The sort oflinguistic fundamentalism that would prescribe necessary conditionsfor an ordinary-language term like person has been effectivelychallenged in recent philosophy, most notably by Wittgenstein. Wehave not the least idea how many ETI sites there may be in our owngalaxy, let alone in the collection of all galaxies. The use of theDrake equation, with its seven (more or less) unknown quantities, toestimate, even very roughly, their actual number is inadmissible,given the state of our knowledge of the processes underlying theprobabilities making up the equation.

Puccetti's argument rests on the assumption that the number of ETIsites can be known to be very great. One has to be wary here of afallacy induced by the contemplation of large numbers. It goes likethis: out of a million planets (with conditions suitable for life,where life has developed, . . .), it is surely a conservativeestimate to suppose that 1 percent, at least, of those will (go onto develop life, will progress toward intelligent life . . .). And,lo! that gives us 10,000 candidates right away. But without a fairdegree of knowledge of the necessary conditions involved in theprocess whose probability is being estimated, this kind of argumentis logically treacherous. It is one thing to discover one or a smallnumber of ETI sites based on the interpretation of incomingradiation. It is another thing entirely to establish, on the basis ofa theoretical analysis of the multiplicity of processes involved inthe appearance and survival of intelligent life, that the number ofcenters of such life in the universe is of a certain order or eventhat it is, in very general terms, extremely large. So I am makingthe much simpler assumption that a single center of ETI isdiscovered, not on the basis of a theoretical analysis of thecomponent genetic processes but directly, by interpretation ofradiation patterns. The consequences for Christian theology are lessdrastic perhaps-Puccetti's not enough time argument cannot getstarted, for example-but in essence they are quite similar.

When people speculate about the implications for Christian theologyof an ETI discovery, they tend to assume that Christian theology is asort of given, that the main outlines of Christian belief are more orless agreed on. But of course this is not the case. Not only arethere significant differences in this regard between Christiandenominations, but even in a single denomination there are areas ofvigorous debate, and particular doctrines can evolve over time. Iturn briefly now to several interrelated Christian doctrines, each ofthem relevant to the ETI discussion, in order to show that thequestions ETI would pose for Christian theology depend quitesensitively on how these doctrines are themselves to be formulated.


1. P. Davies, The Fifth Miracle: The Search for the Origin ofLife (London: Penguin, 1998).

2. F. Hoyle, The Intelligent Universe (London: Michael Joseph, 1983).

3. C. de Duve, Vital Dust (New York: Basic Books, 1995).

4. S. J. Gould, Wonderful Life (Cambridge, Mass.: HarvardUniversity Press, 1989).

5. Favored by Hoyle in Intelligent Universe. See the chapter,Panspermia, in Davies' The Fifth Miracle.

6. For a fuller account, see E. McMullin, Introduction inEvolution and Creation (Notre Dame, Ind.: University of Notre DamePress, 1985), 1-56.

7. A. Plantinga, When Faith and Reason Clash: Evolution and theBible, Christian Scholar's Review, 21 (1991), 8-32; reprinted inD.L. Hull and M. Ruse, eds., The Philosophy of Biology (Oxford:Oxford University Press, 1998), 674-697.

8. E. McMullin, Evolution and Special Creation, Zygon, 28(1993), 299-335; reprinted in The Philosophy of Biology, 698-733.

9. S.J. Dick, Plurality of Worlds (Cambridge: CambridgeUniversity Press, 1982), chapter 2.

10. Reformation theologians, on the other hand, tended toemphasize the uniqueness both of the Incarnation and of the Bible.Philip Melanchthon explicitly rejected the possibility of a pluralityof inhabited worlds on these grounds. T.J. O'Meara, ChristianTheology and Extraterrestrial Life, Theological Studies, 60 (1999),3-30; 6.

11. M.J. Crowe, The Extraterrestrial Life Debate, 1750-1900(Cambridge: Cambridge University Press, 1986).

12. T. Paine, The Age of Reason, in E. Foner, ed., Thomas Paine:Collected Writings (New York: Library of America, 1995), 704.

13. Ibid., The Age of Reason, 708.

14. Ibid., 710.

15. Ibid., 705.

16. Ibid., 709.

17. Ibid., 710.

18. R. Puccetti, Persons: A Study of Possible Moral Agents inthe Universe (New York: Herder and Herder, 1969).

19. P.F. Strawson, Individuals (New York: Doubleday, 1963).

20. Puccetti, Persons, 139.

21. For a detailed critique, see E. McMullin, Persons in theUniverse, Zygon, 15 (1980), 69-89.

22. P. Ricoeur, The Symbolism of Evil (New York: Harper, 1967),232-278; S.J. Duffy, Our Hearts of Darkness: Original SinRevisited, Theological Studies, 49 (1988), 597-622.

23. A few examples: G. Daly, Theological Models in the Doctrineof Original Sin, Heythrop Journal, 13 (1972), 121-152; C. Duquoc,New Approaches to Original Sin, Cross Currents, 28 (1978), 189-200.E.L. Mascall remarks: The fact of original sin is undeniable, butits adequate formulation is the despair of theologians, ChristianTheology and Natural Science (London: Longmans, 1956), 43.

24. Once again, there is a large literature in this area. Seethe bibliography appended in W.S. Brown, N. Murphy, and H.N. Malony,eds., Whatever Happened to the Soul: Scientific and TheologicalPortraits of Human Nature (Minneapolis: Fortress, 1998).

25. N. Murphy, Non-reductive Physicalism, in Whatever Happenedto the Soul, 127-148; E. McMullin, Biology and the Theology of HumanNature, in P. Sloan, ed., Controlling Our Destinies: Historical,Philosophical, and Ethical Perspectives on the Human Genome Project(Notre Dame, Ind.: University of Notre Dame Press, 2000), 367-393;Arthur Peacocke, Science and the Christian Experiment (London: OxfordUniversity Press, 1971), 148-154.

26. M. Luther, Sermons of Martin Luther, ed. and transl. John N.Lenker (Grand Rapids, Mich.: Baker, 1988), 8, 376-377; quoted inJames T. Burtchaell, Philemon's Problem (Grand Rapids, Mich.:Eerdmans, 1998), 75-76.

27. J.T. Burtchaell, His Father's Son, Firstborn of ManyChildren, op. cit., 59-84.

28. The view defended by J.J. Davis in Search forExtraterrestrial Intelligence and the Christian Doctrine ofRedemption, Science and Christian Belief, 9 (1997), 21-34.

29. E.L. Mascall, Christian Theology and Natural Science, 36-45.

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