Cosmological Argument for the Existence of God
COSMOLOGICAL ARGUMENT FOR THE EXISTENCE OF GOD
The cosmological argument is actually a family of arguments that seek to demonstrate the existence of a sufficient reason or first cause of the existence of the cosmos. Among the proponents of the cosmological argu-ment stand many of the most prominent figures in the history of western philosophy: Plato, Aristotle, Ibn Sīnā, al-Ghazālī, Maimonides, Anselm, Aquinas, Scotus, Descartes, Spinoza, Leibniz, and Locke, to name but some. The arguments offered by these thinkers can be grouped into three basic types: (1) what may be called the kalam cosmological argument for a first cause of the beginning of the universe; (2) the Thomist cosmological argument for a sustaining ground of being of the world; and (3) the Leibnizian cosmological argument for a sufficient reason why anything at all exists.
The kalam cosmological argument derives its name from the Arabic word designating medieval Islamic scholasticism, the intellectual movement largely respon-sible for developing this version of the cosmological argument. It originated in the efforts of Christian philosophers such as John Philoponus who, out of their commitment to the biblical teaching of creatio ex nihilo, sought to rebut the Aristotelian doctrine of the eternity of the universe. The argument aims to show that the universe had a beginning at some moment in the finite past and, because something cannot come out of nothing, must therefore have a transcendent cause that brought the universe into being.
By contrast the Thomist cosmological argument, named for the medieval philosophical theologian Thomas Aquinas, seeks a cause that is first—not in the temporal sense, but in the sense of rank. On Aquinas's Aristotelian-inspired metaphysic, every existing finite thing is composed of essence and existence and is therefore radically contingent. A thing's essence is a set of properties that serve to define what that thing is. Now if an essence is to be instantiated, there must be conjoined with that essence an act of being. This act of being involves a continual bestowal of being, or the thing would be annihilated. Essence is in potentiality to the act of being, and therefore without the bestowal of being the essence would not be instantiated.
For the same reason no substance can actualize itself; for in order to bestow being upon itself it would have to be already actual; a pure potentiality cannot actualize itself but instead requires some external cause. Although Aquinas argued that there cannot be an infinite regress of causes of being (because in such a series all the causes would be merely instrumental and so no being would be produced, just as no motion would be produced in a watch without a spring even if it had an infinite number of gears) and that therefore there must exist a first uncaused cause of being, his actual view was that there can be no intermediate causes of being at all, that any finite substance is sustained in existence immediately by the ground of being. This must be a being that is not composed of essence and existence and, hence, requires no sustaining cause. One cannot say that this being's essence includes existence as one of its properties, for existence is not a property, but an act, the instantiating of an essence. Therefore, one must conclude that this being's essence just is existence. In a sense, this being has no essence; rather it is the pure act of being, unconstrained by any essence. It is, as Thomas says, ipsum esse subsistens, the act of being itself subsisting. Thomas identifies this being with the God whose name was revealed to Moses as "I am" (Exod. 3.15).
The German polymath Gottfried Wilhelm Leibniz, for whom the third form of the argument is named, sought to develop a version of the cosmological argument from contingency without the Aristotelian metaphysical underpinnings of the Thomist argument. "The first question which should rightly be asked," he wrote, "will be, Why is there something rather than nothing? " ("The Principles of Nature and of Grace, Based on Reason," §7, p. 527). Leibniz meant this question to be truly universal, not merely to apply to finite things. On the basis of his principle of sufficient reason (PSR) that "no fact can be real or existent, no statement true, unless there be a sufficient reason why it is so and not otherwise" ("The Monadology," §32, p. 539), Leibniz held that this question must have an answer. It will not do to say that the universe (or even God) just exists as a brute fact. There must be an explanation why it exists. He went on to argue that the sufficient reason cannot be found in any individual thing in the universe, nor in the collection of such things which is the universe, nor in earlier states of the universe, even if these regress infinitely. Therefore, there must exist an ultramundane being that is metaphysically necessary in its existence, that is to say, its nonexistence is impossible. It is the sufficient reason for its own existence as well as for the existence of every contingent thing.
The Leibnizian Cosmological Argument
Undoubtedly, the most controversial premise in the Leibnizian cosmological argument is the PSR. The principle as stated in "The Monadology" has seemed, to many, evidently false. Not every fact can have an explanation, for there cannot be an explanation of what has been called the big conjunctive contingent fact (BCCF) that is itself the conjunction of all the contingent facts there are; for if such an explanation is contingent, then it, too, must have a further explanation; whereas if it is necessary, then the fact explained by it must also be necessary. But the explanation cannot have a further explanation, because the BCCF includes all the contingent facts there are; and the fact explained by it cannot be necessary, because the BCCF is contingent.
Some proponents of the cosmological argument have responded to this objection by abandoning the PSR and agreeing that one must ultimately come to some explanatory stopping point that is simply a brute fact, a being whose existence is unexplained. For example, Richard Swinburne (1991) argues that God, as the brute ultimate, is the best explanation of why everything else exists, because as a unique and infinite being God is simpler than the variegated and finite universe.
But other theists have sought to defend the Leibnizian argument without retreating to the dubious position that God is a contingent being. They have either challenged the assumption that there is a BCCF or sought to provide an acceptable explanation of it. It may well be that the existence of a BCCF is inherently paradoxical (compare the set of all truths), so that its existence cannot just be assumed. But if there is such a fact, then the claim that its explanation cannot be found in a necessary truth presupposes that explanations must entail the facts they serve to explain. If some fact is materially implied by a necessary truth, then it may be explained by that truth without itself being necessary.
Some theists have suggested that the BCCF may be explained by the necessary truth that God has weighed the reasons for creating each world and has freely chosen which world to create. Moreover, the claim that the BCCF cannot be explained by some contingent truth assumes, even more controversially, that no contingent truth can be self-explained. The reason why the BCCF is true may be simply because each of its conjuncts is true; nothing more is needed to explain why the BCCF is true than the truth of its atomic constituents, each of which has an explanation for its truth. Or again, it may be supposed that the explanation for the BCCF is that God freely wills the BCCF. Because that explanation is itself a contingent fact, it is also a constituent of the BCCF willed by God. It may then be regarded as self-explained or its explanation may be that God wills that he wills the BCCF, which fact will also be a constituent of the BCCF to be similarly explained in terms of yet another conjunct. This regress seems to be as innocuous as a series of entailments such as its being true that it is true that p. The entire regress is contained in the BCCF and so is willed by God.
This debate is, in any case, somewhat academic because the cosmological argument does not depend for its success on anything so strong as Leibniz's own version of the PSR. For example, in their discussion of Hartry Field's anti-Platonist claim that it is an inexplicable contingency whether mathematical objects exist, Crispin Wright and Bob Hale (1992), while rejecting the demand for an explanation of something such as the BCCF, nevertheless maintain that explicability is the default position and that exceptions to this rule have to be explicable exceptions—some explanation is needed for why no explanation is possible. For example, they claim that if physical existence is at issue, Leibniz's question, "Why is there something rather than nothing?" is an unanswerable question if a satisfactory explanation of why a physical state of affairs obtains has to advert to a causally prior situation in which it does not obtain, because a physically empty world would not cause anything. Wright and Hale believe that the demand for an explanation of the contingency of physical existence is preempted by the restrictive principle that "the explanation of the obtaining of a (physical) state of affairs must advert to a causally prior state of affairs in which it does not obtain" (Wright and Hale 1992, p. 128). Such a principle will be seen by the theist, however, as not at all restrictive, because the explanation of why the physical world exists can and should be provided in terms of a causally prior nonphysical state of affairs involving God's existence and will.
The proponent of the Leibnizian cosmological argument could generate an argument by holding, in conjunction with the above principle, that the obtaining of any physical state of affairs has an explanation. Or the proponent could claim that for any contingently existing thing, there is an explanation why that thing exists; or assert that everything that exists has an explanation of its existence, either in the necessity of its own nature or in an external cause; or, more broadly, maintain that in the case of any contingent state of affairs, there is either an explanation for why that state of affairs obtains or else an explanation of why no explanation is needed. All of these are more modest, nonparadoxical, and seemingly plausible versions of the PSR.
A simple statement of a Leibnizian cosmological argument might run as follows:
- Anything that exists has an explanation of its existence, either in the necessity of its own nature or in an external cause.
- If the universe has an explanation of its existence, that explanation is God.
- The universe exists.
- Therefore the explanation of the existence of the universe is God.
The version of the PSR in premise (1) is compatible with there being brute facts or states of affairs about the world. But there are two kinds of being: necessary beings, which exist of their own nature and so have no external cause of their existence, and contingent beings, whose existence is accounted for by causal factors outside themselves. Numbers might be prime candidates for the first sort of being, whereas familiar physical objects fall under the second kind of being.
Premise (2) is, in effect, the contrapositive of the typical atheist response to Leibniz that on the atheistic worldview the universe simply exists as a brute contingent thing. Atheists typically assert that, there being no God, the universe just exists inexplicably. Moreover, (2) seems plausible in its own right, for if the universe, by definition, includes all of physical reality, then the cause of the universe must (at least causally prior to the universe's existence) transcend space and time and therefore cannot be physical or material. But there are only two kinds of things that could fall under such a description: either an abstract object or else a mind. But abstract objects do not stand in causal relations. Therefore it follows that the explanation of the existence of the universe is an external, transcendent, personal cause—which is one meaning of "God."
Finally, premise (3) states the obvious—that there is a universe. Because the universe exists, it follows that God exists.
It is open to the nontheist to retort that whereas the universe has an explanation of its existence, that explanation lies not in an external ground but in the necessity of its own nature; in other words, (2) is false. The universe is a metaphysically necessary being. This is an extremely bold suggestion. One may safely say that there is a strong intuition of the universe's contingency. A possible world in which no concrete objects exist certainly seems conceivable. People generally trust their modal intuitions on other matters with which they are familiar; if they are to do otherwise with respect to the universe's contingency, then the nontheist needs to provide some reason for such skepticism other than the desire to avoid theism.
The Thomist Cosmological Argument
Still, it would be desirable to have some stronger argument for the universe's contingency than modal intuitions alone. Could the Thomist cosmological argument help out here? If successful, it would show that the universe is a contingent being causally dependent upon a necessary being for its continued existence. The difficulty with appeal to the Thomist argument, however, is that it is difficult to show that things are, in fact, contingent in the special sense required by the argument. Certainly things are naturally contingent in that their continued existence is dependent upon myriad factors including particle masses and fundamental forces, temperature, pressure, entropy level, and so forth, but this natural contingency does not suffice to establish things' metaphysical contingency in the sense that being must continually be added to their essences lest they be spontaneously annihilated. Indeed, if Thomas's argument does ultimately lead to an absolutely simple being whose essence is existence, then one may well be led to deny that beings are metaphysically composed of essence and existence if the idea of such an absolutely simple being proves to be unintelligible.
The Kalam Cosmological Argument
But perhaps the kalam cosmological argument can reinforce the Leibnizian argument. For an essential property of a metaphysically necessary being is eternality, that is to say, existing without beginning or end. If the universe is not eternal, then, it could not be a metaphysically necessary being.
It may be countered that a being with a temporal beginning or end could be metaphysically necessary in that it exists in all possible worlds. But the notion of metaphysical necessity that underlies this suggestion fails to take tense seriously and may therefore seem inadequate. Metaphysicians have in recent years begun to appreciate the metaphysical importance of whether time is tensed or tenseless; that is to say, whether items in the temporal series are ordered objectively as past, present, or future, or whether, alternatively, they are ordered merely by tenseless relations of earlier than, simultaneous with, and later than. Possible worlds semantics is a tenseless semantics and so is incapable of expressing the significance of one's view of time and tense. In particular, it is evident that a truly necessary being, one whose nonexistence is impossible, must exist at every moment in every world. It is not enough for it to exist at only some moment or moments in every possible world; for the fact that there exist moments in various worlds at which it fails to exist shows that its nonexistence is not impossible. Furthermore, a truly metaphysically necessary being must exist either timelessly or sempiternally in any tensed world in which it exists, for otherwise its coming into being or ceasing to be would again make it evident that its existence is not necessary, even if it existed at every moment in worlds in which time had a beginning or end.
But it is precisely the aim of the kalam cosmological argument to show that the universe is not sempiternal but had a beginning. It would follow that the universe must therefore be contingent in its existence. Indeed, the kalam argument shows the universe to be contingent in a special way: It came into existence out of nothing. The nontheist who would answer Leibniz by holding that the existence of the universe is a brute fact, an exception to the PSR, is thus thrust into the awkward position of maintaining not simply that the universe exists eternally without explanation, but rather that for no reason at all it magically popped into being out of nothing, a position that might make theism look like a welcome alternative.
The kalam cosmological argument may be formulated as follows:
- Whatever begins to exist has a cause.
- The universe began to exist.
- Therefore, the universe has a cause.
Conceptual analysis of what it means to be a cause of the universe then helps to establish some of the theologically significant properties of this being.
Premise (1) seems obviously true—at the least, more so than its negation. It is rooted in the metaphysical intuition that something cannot come into being from nothing. Moreover, this premise is constantly confirmed in human experience. The conviction that an origin of the universe requires a causal explanation seems reasonable, for on the atheistic view, if the universe began at the big bang, there was not even the potentiality of the universe's existence prior to the big bang, because nothing is prior to the big bang. But then how could the universe become actual if there was not even the potentiality of its existence? It makes much more sense to say that the potentiality of the universe lay in the power of God to create it.
Often it is said that quantum physics furnishes an exception to premise (1), because on the subatomic level events are said to be uncaused. This objection, however, is based on misunderstandings. In the first place, not all scientists agree that subatomic events are uncaused. A great many physicists today are dissatisfied with this view (the so-called Copenhagen Interpretation) of quantum physics and are exploring deterministic theories like that of David Bohm (Cushing, et al, 1996). Thus, quantum physics is not a proven exception to premise (1). Second, even on the traditional, indeterministic interpretation, particles do not come into being out of nothing. They arise as spontaneous fluctuations of the energy contained in the subatomic vacuum, which constitutes an indeterministic cause of their origination. Thus, there is no basis for the claim that quantum physics proves that things can begin to exist without a cause, much less that the universe could have sprung into being uncaused from literally nothing.
Premise (2), the more controversial premise, may be supported by both deductive, philosophical arguments and inductive, scientific arguments. Classical proponents of the kalam argument contended that an infinite temporal regress of events cannot exist, because the existence of an actually infinite number of things leads to intolerable absurdities.
It is usually alleged that this sort of argument has been invalidated by Georg Cantor's work on the actual infinite and by subsequent developments in set theory (e.g., Sobel). But this allegation gratuitously presupposes a Platonistic view of mathematical objects that the argument's defender is at liberty to reject. Cantor's system and set theory may be taken to be simply a universe of discourse, a mathematical system based on certain adopted axioms and conventions. The argument's defender may hold that whereas the actual infinite may be a fruitful and consistent concept within the postulated universe of discourse, it cannot be transposed into the spatio-temporal world, for this would involve counterintuitive absurdities. A fictionalist understanding of abstract objects or a divine conceptualism combined with the simplicity of God's cognition is at least a tenable alternative to Platonism.
A second argument for the beginning of the universe offered by classical proponents of kalam is that the temporal series of past events cannot be an actual infinite because a collection formed by successive addition cannot be actually infinite, an argument that eventually became enshrined in the thesis of Kant's first antinomy concerning time. Sometimes the problem is described as the impossibility of traversing the infinite. In order for one to have "arrived" at today, temporal existence has, so to speak, traversed an infinite number of prior events. But before the present event could arrive, the event immediately prior to it would have to arrive; and before that event could arrive, the event immediately prior to it would have to arrive; and so on ad infinitum. No event could ever arrive, because before it could elapse there will always be one more event that has had to have happened first. Thus, if the series of past events were beginningless, the present event could not have arrived, which is absurd.
It is frequently objected that this sort of argument illicitly presupposes an infinitely distant starting point in the past and then pronounces it impossible to travel from that point to today. But if the past is infinite, then there would be no starting point whatever, not even an infinitely distant one. Nevertheless, from any given point in the past, there is only a finite distance to the present, which is easily traversed.
But proponents of the kalam argument have not in fact assumed that there was an infinitely distant starting point in the past. The fact that there is no beginning at all, not even an infinitely distant one, seems only to make the problem worse, not better. To say that the infinite past could have been formed by successive addition is like saying that someone has just succeeded in writing down all the negative numbers, ending at −1. And, one may ask, how is the claim that from any given moment in the past there is only a finite distance to the present even relevant to the issue? For the question is how the whole series can be formed, not a finite portion of it. To think that because every finite segment of the series can be formed by successive addition the whole infinite series can be so formed is to commit the fallacy of composition.
A third argument for the universe's beginning is an inductive argument based on contemporary evidence for the expansion of the universe. According to the standard big bang model, as time proceeds, the distances separating galactic masses become greater. It is important to understand that the model does not describe the expansion of the material content of the universe into a preexisting, empty space, but rather the expansion of space itself. This has the astonishing implication that as one reverses the expansion and extrapolates back in time, the universe becomes progressively denser until one arrives at a so-called singularity at which space-time curvature, along with temperature, pressure, and density, becomes infinite. It therefore constitutes an edge or boundary to space-time itself.
The history of twentieth-century cosmology has, in one sense, been a series of failed attempts to craft acceptable nonstandard models of the expanding universe in order to avert the absolute beginning predicted by the standard model. Whereas such theories are possible, it has been the overwhelming verdict of the scientific community than none of them is more probable than the big bang theory. There is no mathematically consistent model that has been so successful in its predictions or as corroborated by the evidence as the traditional big bang theory. For example, some theories, such as the oscillating universe (which expands and recontracts forever) or the chaotic inflationary universe (which continually spawns new universes), do have a potentially infinite future but turn out to have only a finite past. Vacuum fluctuation universe theories (which postulate an eternal vacuum out of which this universe is born) cannot explain why, if the vacuum was eternal, one does not observe an infinitely old universe. The no-boundary universe proposal of James Hartle and Stephen Hawking, if interpreted realistically, still involves an absolute origin of the universe even if the universe does not begin in a singularity, as it does in the standard big bang theory. More recently proposed ekpyrotic cyclic universe scenarios based on string theory or M-theory have also been shown not only to be riddled with problems, but, most significantly, to imply the origin of the universe that its proponents sought to avoid. Of course, scientific results are always provisional, but there is no doubt that the defender of the kalam argument rests comfortably within the scientific mainstream.
A fourth argument for the finitude of the past is also an inductive argument, appealing to implications of physical eschatology. According to the second law of thermodynamics, processes taking place in a closed system always tend toward a state of equilibrium. The universe is, on a naturalistic view, a gigantic closed system, because it is everything there is and there is nothing outside it. What this seems to imply is that, given the probability that the universe will expand forever, the universe will in the finite future degenerate into a cold, dark, lifeless, highly dilute condition, as it asymptotically approaches equilibrium. Now if, given enough time, the universe will reach such a condition, then why is it not in such a condition now, if it has existed forever, from eternity? Because it is not in such a state, the universe must have begun to exist.
Some have tried to escape this conclusion by proposing an oscillating model of the universe that restores an appearance of youth to an infinitely old cosmos. But even apart from the physical and observational problems plaguing such models, the thermodynamic properties of such a universe imply the very beginning that its proponents sought to avoid—for entropy increases from cycle to cycle in such a model, which has the effect of generating larger and longer oscillations with each successive cycle. Hence, the oscillating model has an infinite future, but only a finite past.
Even if this difficulty were avoided, a universe oscillating from eternity past would require an infinitely precise tuning of initial conditions in order to last through an infinite number of successive bounces. A universe rebounding from a single, infinitely long contraction is, if entropy increases during the contracting phase, thermodynamically untenable and incompatible with the initial low entropy condition of the expanding phase. Postulating an entropy decrease during the contracting phase in order to escape this problem would require one to postulate inexplicably special low entropy conditions at the time of the bounce in the life of an infinitely evolving universe. Such a low entropy condition at the beginning of the expansion is more plausibly accounted for by the presence of a singularity or some sort of quantum creation event.
From the two premises it follows logically that the universe has a cause. Protagonists of kalam maintain that a conceptual analysis of what properties must be possessed by such an ultramundane cause enables one to recover a striking number of the traditional divine attributes, revealing that if the universe has a cause, then an uncaused, personal creator of the universe exists who sans the universe is beginningless, changeless, immaterial, timeless, spaceless, and enormously powerful. This creator will be, as Leibniz maintained, the sufficient reason why anything at all exists.
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