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William Ockham on Divine Omnipotence and the Plurality of Worlds
What is nature? How is nature known? These now familiar questions received their most important medieval reformulation in the natural philosophy of William of Ockham, born around 1290. Ockham joined the Franciscan order and began theological studies at Oxford around 1310. In both theology and natural philosophy, the overriding theme of Ockham's thought was divine omnipotence. He explained that he strove to work out the implications of the first line of the Apostle's creed, "I believe in God the Father Almighty..." For Ockham, divine omnipotence meant that God can do anything not involving a contradiction.
From this premise it follows that (contrary to Aristotle) there are no essential, necessary "natures" or universals that determine what individual things or "particulars" must be. Because of Ockham's emphasis on the reality of particulars (one instance of his application of divine omnipotence), Ockham's philosophy is often referred to as "nominalism" or "terminism." In other words, Ockham regarded universal statements merely as useful names ("nominalism") or terms ("terminism"), rather than necessary realities.
Ockham's "razor" is an oft-cited maxim that instructs scientists, when there are multiple possible explanations, to choose the one that is simpler. If this principle of economy were all there was to it, however, it would not be new or associated with Ockham (e.g., Aristotle said that "many [principles] are in vain where few would suffice"). Actually, Ockham's razor arose in the specific context described above, as part of his critique of necessary universals, and of deductive reasoning based upon them. Ockham's famous "razor" is a principle of economy by which one should dispense with the categories of natures or essences that require individual things to be the way they are. Ockham argued that since, in view of divine omnipotence, one does not need to postulate universals, one shouldn't, on the basis of economy.
So if individual things are singular, and not determined by universal natures, then how are similar things related, and how can these relations be known? The answer for Ockham is that each thing is one of a kind, and the relations between them are contingently ordered rather than necessary. There are no necessary relations between individuals, which would place limits on divine freedom and omnipotence. In other words, every thing that is real and that is not God is contingent to the core of its being. (A thing is "contingent" if it might have been otherwise; see the earlier discussion of contingency in the thought of Basil and Augustine.)
In contrast to Aristotle, Platonists and Thomists, for Ockham similarities between individuals (for example, individual people or individual planets) are simply a matter of fact, of their contingent ordering by divine will, not of metaphysical necessity. In contrast to reasoning from the essences or natures of things, according to Ockham we are not allowed to affirm a statement or to maintain that something exists, unless we can cite:
These are the criteria Ockham applied to cut away imaginary entities asserted by reasoning from allegedly necessary principles. Unless one can point to one of these criteria, then Ockham will not admit a conclusion; this skepticism is his razor in action.
In other words, for Ockham we cannot know what God has in fact done (how he chose to contingently order the world) by reason alone, or from metaphysical necessity. Instead of reaching certainty through deductive argument, questions about natural and human order must remain open to empirical investigation, and will yield only probable rather than certain knowledge. All knowledge of the ordering of the contingent world that God actually chose to create must derive from experience, selected by the razor. The universe is radically contingent, and our ability to grasp its reality does not yield certainty but only probable knowledge. For example, Ockham wrote that the stars could now at this moment be annihilated, though we would continue to intuit their existence. There is evidence but not certainty; only probable and conditional knowledge is possible.
Because of these radical departures from the views of reality and knowledge of nature held by Aristotle and by Thomas Aquinas, one might wonder how Ockham was regarded by the Church. On the one hand, his work can be seen as carrying on the tradition of Augustine. On the other hand, for many reasons, these were turbulent times for Roman Catholicism and for European culture. In 1315, Pope John XXII moved from Rome to Avignon, France, in what was often called the Babylonish Captivity. Eight years later the former chancellor of Oxford visited John XXII with 56 charges of erroneous or heretical propositions culled from Ockham's writings. Before deliberations on the charges could be concluded, the papal commision was sidetracked by a controversy concerning the elected General of the Franciscan order, Michael Cesena, who advocated ecclesiastical poverty and opposed the accumulation of wealth by the Church. As a Franciscan, Ockham vigorously defended his General. In 1328, Michael fled Avignon by night, accompanied by Ockham, for the friendlier company of Louis of Bavaria, Holy Roman Emperor. Louis' claim to the crown was contested by John XXII, and Ockham wrote in defense of the emperor, but in opposition to John and two successive popes, on the relations of secular and ecclesiastical authority. For these writings in ecclesiastical and political philosophy, in defense of separate spheres of authority of church and state, Ockham was excommunicated.
In many ways Ockham remains an enigma, even to modern writers. Many historians of science regard him as a founder of empirical methodologies in science. Yet others with a more Thomistic view of reality see him as a logician whose logical distinctions and thought experiments became divorced from reality. Many Catholic theologians regret his influence as a skeptic who fragmented Roman Catholicism by undermining Thomism; many Protestant theologians hail him as a forerunner of the Reformation -- Luther called Ockham his "master," i.e., teacher. Political historians often see his ecclesiastical writings as laying a foundation for the eventual separation of the authority of church and state. Ockham was one of the three most important medieval philosophers, along with Thomas Aquinas and John Duns Scotus. Ockham died in 1349, perhaps a victim of Black Plague.
The following text provides a sample of Ockham's natural philosophy, and his radical revision of Aristotle's doctrine of natural place in a discussion of the possible existence of other Earth-like planets (a possibility Aristotle denied).
Note: Throughout this web page, "Earth" (capitalized) refers to the Earth as a planet or globe; "earth" (lower case) refers to the element earth, one of the four Aristotelian elements that occur beneath the Moon.
Aristotle's theory of natural motion, although based upon common sense, entailed a number of necessary consequences, including the impossibility of multiple universes and of multiple Earth-like planets. Let's recall the reasoning for the latter impossibility. According to Aristotle, an earthy rock dropped a few feet off the surface of the Earth falls down because the element earth has a natural motion toward the center of the universe. The element earth gathers in a globe in the center of the universe, and cannot gather anywhere else. Everywhere else it naturally tends toward the center in a straight line, unless something else holds it back.
So what would happen, according to Aristotle, if you were an astronaut standing on the surface of the Moon, and dropped an earthy rock? Aristotle's answer would be that the rock would fall not down toward the Moon, but toward the center of the universe, which is the center of the planet Earth. An earthy rock dropped near the surface of Mars or any other Earth-like planet would similarly fall toward the center of the universe, that is, toward the Earth, and therefore it would be impossible for any other Earthlike planets to exist.
In the following excerpt, to preserve the prerogatives of divine omnipotence, William Ockham reformulated Aristotle's theory of natural motion in order to refute Aristotle's necessary prohibition of multiple Earth-like planets. Ockham substitutes a theory where elements move to positions of relative natural place, instead of Aristotle's absolute natural place. Similar arguments will be used by Copernicus in 1543, as we shall see.
William of Ockham, Ordinatio, Bk I, d. 44, q. 1, based upon the translations of Steven J. Livesey and Roger Ariew (cited below, p. 463). I have added explanatory headings in bold print, and text clarifications in [square brackets].
Introduction
"I say that God can make a world better than this one, which would
be only numerically distinct from this world. The reason is as follows: God
can produce an infinite number of individuals of the same ratio ("ratio"
roughly means kind, species, idea, essence, definition, etc.) as those which
exist now. Therefore, God can produce as many or more individuals as already
have been produced, and He can make them of the same species. But he is not
compelled to produce them in this world. He can produce them outside this world,
and from them make another world, just as he made this world from those things
which exist now.
Summary of Aristotle's argument that the element earth
must move naturally in the same direction, and therefore that all earth must
be in the same location
But if it is argued -- as the Philosopher [Aristotle] argues in De caelo
[On the Universe], Bk 1 -- that if there were another world [Earth-like
planet], the earth of that world should move to the middle of this world. [Aristotle
would say that] This cannot be denied since bodies of the same ratio
[kind] are moved to the same place. Therefore, since the earth of this world
is moved naturally to the middle of this world, the earth of another world would
be moved naturally to the middle of that world. [According to Aristotle, this
is impossible, because] If, however, the earth of the other world were to be
moved naturally to the middle of that world, it would recede naturally from
the middle of this world, which is impossible, since heavy bodies are never
moved naturally away from the middle....
Ockham notes that two fires, rising to the heaven from opposite sides
of the Earth, rise in different directions
To [Aristotle's argument], I say that.... If someone put two different fires
of the same kind into two different locations on the earth, they would both
rise toward the circumference of the heavens, but they would not both tend toward
the same place; they would move toward two numerically distinct places. However,
if someone took the first fire and put it where the second fire was, the first
fire would tend toward the place where the second tended.
So it is in the question now occupying us. If someone were to take the earth belonging to the other world and put it inside our heaven, it would tend toward the same place as our earth. But when it is outside this world [extra istum mundum], and inside the heaven of the other world, it would no longer move toward the center of this world --no more than a fire at Oxford would tend toward the same place where it would tend if it were put in Paris -- but it would moved toward the center of the other world.
It is not only because the two earths are numerically distinct that they move toward two distinct places, as maintained by the objection Aristotle was refuting [276b32-277a9]; they would move toward the two numerically different places because they occupy two different positions in the heavens -- just as two fires are moved to two numerically different portions of heaven because of their different locations...
Armand Maurer, “Ockham on the Possibility of a Better World,” Mediaeval Studies 38 (1976): 291–312.
Pierre Duhem, Medieval Cosmology: Theories of Infinity, Place, Time, Void, and the Plurality of Worlds, ed. and trans. by Roger Ariew (Chicago: Chicago University Press, 1987), ch. 12.
Steven J. Dick, Plurality of Worlds: The Extraterrestrial Life Debate from Democritus to Kant (Cambridge: Cambridge University Press, 1984).
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HSCI 3013. History
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Many thanks to the pedagogical model developed in Mythology and Folklore and other online courses by Laura Gibbs, which have been an inspiration for this course.
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This course is currently undergoing major reconstruction to bring it into alignment with the new version of the course at Janux |
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