DEGREES OF PERFECTION, ARGUMENT FOR THE EXISTENCE OF GOD

The proof for the existence of God from degrees of perfection, sometimes called the Henological Argument, finds its best-known expression as the fourth of Thomas Aquinas's "Five Ways" in his Summa Theologiae Ia, 2, 3. It is here quoted in full:

The fourth way is based on the gradation observed in things. Some things are found to be more good, more true, more noble, and so on, and other things less. But comparative terms describe varying degrees of approximation to a superlative; for example, things are hotter and hotter the nearer they approach what is hottest. Something therefore is the truest and best and most noble of things, and hence the most fully in being; for Aristotle says that the truest things are the things most fully in being. Now when many things possess some property in common, the one most fully possessing it causes it in the others: fire, to use Aristotle's example, the hottest of all things, causes all other things to be hot. There is something therefore which causes in all other things their being, their goodness, and whatever other perfections they have. And this we call God.

Comparatives and Superlatives

A distinctive feature of the Fourth Way is the principle that "comparative terms describe varying degrees of approximation to a superlative"; for example, suppose "whiter than" is such a comparative term. The judgment that bond paper is whiter than newsprint would then be more adequately expressed as "The color of bond paper is closer to pure white than is the color of newsprint." However, the new comparative term "closer to" (that is, "more closely resembles," "more similar to") is used in exactly the same sense when none of the things compared is a superlative, for example, in "The color of bond paper is closer to the color of newsprint than the color of newsprint is close to the color of lemons," and here "closer to" obviously does not describe a degree of approximation to pure white. If "closer to," used to compare colors, does describe degrees of approximation to a superlative, the superlative must be the greatest possible similarity between colors, that is, qualitative identity of colors. Perhaps the initial judgment should then be expressed "The similarity between the color of bond paper and pure white is closer to the greatest possible similarity than is the similarity between newsprint and pure white." But here there is still a comparative term, "closer to," used to compare similarities between colors. It seems impossible to define a comparative term by means of a superlative without using another comparative term, and we are on our way to an infinite regress. If all comparative terms describe degrees of approximation to a superlative, then any comparative judgment implicitly refers to infinitely many superlatives.

But perhaps not all comparative terms describe degrees of approximation to a superlative. Suppose "closer to" (as used to compare colors) does not, and therefore the infinite regress can be cut short. Then "closer to" can be used to define "whiter than," and the definition need not refer to pure white, or to any other superlative. This is a reason for denying that "whiter than" describes a degree of approximation to a superlative. The definition runs as follows:

First it must be given, perhaps simply by fiat, that color B is whiter than color A. B need not be pure white, or superlatively white. Then any color X is between A and B if and only if both X is closer to A than A is close to B and X is closer to B than B is close to A. If X is between A and B, then X is whiter than A, and B is whiter than X. If X is different from both A and B and is not between A and B, then (1) X is whiter than B if and only if X is closer to B than X is close to A and (2) A is whiter than X if and only if X is closer to A than X is close to B. Two colors, X and Y, can be compared with respect to whiteness by (1) comparing X with the initially given pair in the manner just described and (2) similarly comparing Y with either the pair A and X or the pair B and X.

Superlative terms can be defined by means of comparatives more easily than comparative terms can be defined by means of superlatives. For example, "Brand X is the whitest bond paper if and only if Brand X is whiter than any other bond paper." Or "Brand X is the whitest bond paper if and only if no other bond paper is whiter than Brand X. " On the second definition there can be more than one whitest bond paper. On the first definition there can be only one; and it is therefore possible that nothing satisfies the first definition. Such nonequivalent forms of definition are possible whatever the kind of superlative term defined; either form may be used if it is not confused with the other. Both definitions above define a relative superlative term. Whitest is defined with respect to a certain class, the class of bond papers. Since not only bond paper is white, neither definition rules out the possibility that something other than bond paper is whiter than the whitest bond paper. A universal superlative term is defined with respect to the class of everything of which the corresponding comparative term is predicable. For example, "X is the whitest thing if and only if nothing is whiter than X. " Both relative and universal superlative terms can be absolute superlative terms. An absolute superlative term is defined by means of a modal term such as possible or can. "X is pure white if and only if it is not possible for anything to be whiter than X. " There are as many senses of an absolute superlative term as there are relevant senses of possible.

Any comparative term can be used to define some superlative term. For example, "greater than" can be used to define "greatest prime number": n is the greatest prime number if and only if n is a prime number and there is no prime number greater than n. But it has been proved that there is no greatest prime number—that the predicate "greatest prime number" cannot be truly predicated of any number. This raises a general question: How can we know whether a particular superlative term could possibly be truly predicated of something? One can define "pure white," but this gives no assurance that there might possibly be something that is pure white. Perhaps we do not know what we are talking about when we talk about "pure white"; for perhaps there can be nothing to talk about, just as there can be nothing to talk about when we talk about "the greatest prime number." A superlative term should be suspected of not being truly predicable of anything possible unless there is a reason to think otherwise, and such a reason is not provided by the fact that the superlative term can be defined by a perfectly understandable comparative term.

Such a reason is sometimes provided when the superlative term can be defined without using any corresponding comparative or superlative terms. Definitions of this sort will usually, perhaps always, employ a universal quantifier. For example, "An object is (absolutely) pure gold if and only if all its atoms are atoms of gold. A perfect reflector is one that reflects all the light falling on it." Definitions of the form "Something is pure ______ if and only if it contains no impurities" or "something is a perfect ______ if and only if it has no imperfections" will not do by themselves. The terms "contains no impurities" and "has no imperfections" are as problematic as the particular superlative terms they define and should be used without qualms only if they can be characterized independently. "Absolutely pure minestrone soup" can be defined as "minestrone soup completely free of impurities," but this is no help until we have a complete list of possible impurities. Aniline dyes are definitely impurities in soups. Some batches of minestrone soup are therefore definitely purer than others. But starting from an incomplete list of possible impurities, there is no obvious way, other than by arbitrary stipulation, of making a complete list. It seems that "absolutely pure minestrone soup" can therefore be given a clear sense only by stipulation. We do not need to give it a clear sense in order to talk sensibly about some batches of soup being purer than others.

A comparative term is often much clearer than the corresponding superlative term; one can often know how to use a comparative term without at all knowing how to use the corresponding superlative term. It seems reasonable to deny that such comparative terms describe degrees of approximation to a superlative.

Perfections

Thomas stated his principle quite generally, but presumably he would have been willing to qualify it. He argued himself that there can be nothing that is unlimited in size (Summa Theologiae Ia, 7, 3) and he would deny, reasonably, that the comparative term "longer than," for example, describes degrees of approximation to a superlative. The argument from degrees of perfection does not lead to the heretical conclusion that God is pure white or pure red. Still less does it lead to the impossible conclusion that God is both pure white and pure red or that God is both perfectly circular and perfectly triangular. The argument is concerned only with perfections whose predication does not imply any sort of imperfection. If a thing is white, it must be extended; if extended, it must be divisible; and if divisible, it must be perishable. Perishability is an imperfection, and therefore whiteness, like all other properties that exist only in something extended, can exist only in things less than completely perfect. Perfections that involve absolutely no imperfection are sometimes called "transcendental perfections." The traditional list includes being, unity, truth, goodness, nobility, and sometimes beauty and intelligence. Thomas thought that anything, a member of any genus, and God, who is not a member of any genus, could have these perfections. For Thomas's argument the principle about comparison need be true only of the transcendental perfections.

The principle about comparison is generally dubious, and it is particularly dubious with the transcendental perfections. Goodness, for example, is sensibly predicated of something only when it is understood as being of some kind. One who asserts of something "It is good" should be prepared always to answer the question "A good what ?" Things of a certain kind are good in virtue of having certain characteristics; things of another kind in virtue of having others. Thus, if comparisons of goodness describe degrees of approximation to a superlative, then comparison with respect to any of the different characteristics admitting of degrees in virtue of which different kinds of things are good must also describe degrees of approximation to a superlative. The restriction of the comparative principle to transcendental perfections is not much of a restriction.

Those who do not subscribe to a Thomistic metaphysics, or to one like it, will not find any reason to accept the principle that comparisons of perfections describe degrees of approximation to a superlative. It is not surprising that Thomas's philosophy contains enough material to construct more arguments for God's existence than he formulated explicitly. Some of these back up the Fourth Way. For example, Thomas's philosophical theology makes great use of the Aristotelian distinction between act and potency: "Each thing is perfect according as it is in act, and imperfect as it is in potency" (Summa contra Gentiles I, 28, 6). Furthermore, something whose actuality is less than complete must be caused by something else with at least as much actuality (I, 28, 7). Bearing these two principles in mind, the argument from degrees of perfection can be reformulated as follows:

Some things are found to be more perfect than others. Thus, some things have less than the superlative degree of perfection. Since a thing's perfection is its actuality, these things have less than the superlative degree of actuality. Something whose actuality is less than complete must be caused by something else with at least as much actuality. The resulting hierarchy of causes cannot be infinite, so there must be a first cause whose actuality is complete, who is pure act, and who therefore has all perfections in a superlative degree. And this we call God.

Thus reformulated, the Fourth Way resembles the First Way, the argument from efficient causality, and the Second Way, the argument from change. And it is susceptible to the same sorts of familiar objections raised against them. These objections, however, may seem less forceful against the Fourth Way than against the other arguments. A modern reader who is untroubled by the idea of an infinite hierarchy of efficient causes may well balk at the idea of an infinite hierarchy of increasing perfection. And one who claims that a proof of a first cause does not prove God's existence may admit that a proof of an absolutely perfect being does. However, this does not make the argument from degrees of perfection more convincing than the other proofs. The argument is now generally neglected, and a modern nonbeliever is not likely to be much influenced by it. For its premises will seem plausible only to one who accepts metaphysical principles, which in turn will seem plausible only to one who has a prior belief in the existence of God.

The reformulation of the Fourth Way given earlier brings out the relevance of the relation between comparative and superlative to other parts of Thomas's system. A central doctrine of Thomas's philosophical theology is that God is pure act, that there neither is nor could be any potency in him. Even if it is granted that we can learn, from Aristotle's and Thomas's examples, how to compare some things as being more or less in act, this gives us no reason to suppose that the superlative term "pure act" is intelligible or that it could possibly apply to something.

See also Aristotle; Perfection; Popular Arguments for the Existence of God; Thomas Aquinas, St.

Bibliography

The Fourth Way seems the most Platonic of Thomas Aquinas's Five Ways. See, for example, Plato, Phaedo, 100–101. Two books in English on Thomas's relation to Plato are Arthur Little, The Platonic Heritage of Thomism (Dublin, 1950), and R. J. Henle, Saint Thomas and Platonism (The Hague: Nijhoff, 1956). The Fourth Way is the major topic of Little's book. Henle's book has a very complete bibliography.

The principle that comparative terms describe varying degrees of approximation to a superlative appears several times in Thomas's Summa contra Gentiles (I, 28, 8, I, 42, 19; I, 62, 5). It does not, however, appear in the very compressed argument for God's existence (I, 13, 34), where an argument from degrees of truth is attributed to Aristotle. Aristotle's Metaphysics II, 993b25–30, a passage mentioned in both the Summa Theologiae and the Summa contra Gentiles versions of the argument, does seem adaptable to Thomas's purposes. Metaphysics IV, 1008b31–1009a5, mentioned only in the Summa contra Gentiles version, does not. Aristotle probably should not be counted among the philosophers who employed or would be willing to employ the argument from degrees of perfection to prove the existence of a perfect being.

Several arguments from degrees of perfection appear in the writings of Augustine; see, for example, Bk. V, Sec. 11, and Bk. VIII, Sees. 4 and 5, of De Trinitate, the work of Augustine's referred to in the preface of Anselm's Monologion. Anselm's arguments from degrees of perfection appear in the first four chapters of the Monologion.

The Blackfriars edition of Thomas's Summa theologiae (New York: McGraw-Hill, 1964–; only a few of the projected 60 vols. have been published so far) has the Latin text, along with a new English translation. The second volume, Ia. 2–11 (New York McGraw-Hill, 1964), translated by Timothy McDermott, contains appendices by Thomas Gilby, "The Fourth Way" and "Perfection and Goodness."

Thomas's doctrine of "analogical" predication is usually invoked to explain the notion of a transcendental perfection. This, as well as the act-potency distinction, is discussed in Knut Tranøy, "Thomas Aquinas," in A Critical History of Western Philosophy, edited by D. J. O'Connor (New York: Free Press of Glencoe, 1964), and further references are given.

The Fourth Way is the least widely accepted of Thomas's proofs for the existence of God. References to the disputes are given in Étienne Gilson, The Christian Philosophy of St. Thomas Aquinas (New York: Random House, 1956). See also Gilson's Elements of Christian Philosophy (New York: Doubleday, 1960).

René Descartes presented a proof for the existence of God from the degrees of perfection found in ideas. See his Third Meditation, his Principles of Philosophy, I. xviii., Objection II of the second set of Objections to the Meditations, and his Reply to this objection.

Bobik, Joseph. "Aquinas's Fourth Way and the Approximating Relation." The Thomist 51 (1987): 17–36.

Brady, Jules. "Note on the Fourth Way." New Scholasticism 48 (1974): 219–232.

Catan, John, ed. St. Thomas Aquinas on the Existence of God: Collected Papers of Joseph Owens. Albany: State University of New York Press, 1980.

Dewan, Lawrence. "St. Thomas's Fourth Way and Creation." The Thomist 59 (1995): 371–378.

Kenny, Anthony. The Five Ways: St. Thomas Aquinas' Proofs of God's Existence. London: Routledge and Kegan Paul, 1969.

Morreall, John. "Aquinas' Fourth Way." Sophia 18 (1979): 20–28.

Urban, Linwood. "Understanding St. Thomas's Fourth Way." History of Philosophy Quarterly 1 (1984): 281–296.

Wippel, John. The Metaphysical Thought of Thomas Aquinas: From Finite Being to Uncreated Being. Washington, DC: Catholic University of America Press, 2000.

David Sanford (1967)

Bibliography updated by Christian B. Miller (2005)