A rabbit caught in a trap: the Ontological Argument & Aquinas' 4th Way
In St. Thomas Aquinas' work Summa Theologica, the saint-theologian argues, among other things, for the existence of God based upon five ways of using human reason to bring his readers to the threshold of faith in God's existence. The fourth of these ways is known as the argument from degrees or gradation. In this way, St. Thomas begins observing that when describing the quality of certain things, they can be characterized by the ways in which they conform, to a greater or lesser degree, to that which is conceived of as the maximum or minimum. St. Thomas cites the examples of the best, the noblest, and the truest. He relates these examples to the notion that the extremes of the transcendentals—already cited above—are correspondent to that which is the uttermost being. This uttermost being causes that which is within its genus: for example, fire as the uttermost being of heat causes all lesser heats. Since, therefore, one can observe degrees or gradations of truth, goodness, and beauty, there must exist something which is the uttermost being of truth, goodness, and beauty. This uttermost being is, for St. Thomas, God.
Aquinas' fourth way is reminiscent of St. Anselm's ontological argument for the existence of God, though it differs in a significant way. For St. Anselm, the arguments begins with the conception in the mind of the philosopher of that which is the best, truest, and most beautiful supreme being. This being, of course, would have to be infinite in order to meet the criteria. But, as argued above in Question One, St. Anselm's effort to conceive of the supreme being must necessarily fail at the moment that it is conceived because the conception itself is done by a creature which is finite. In this way, St. Anselm's argument brings the philosopher close to an understanding of what this highest being must be; at the same time, however, one is infinitely distant from perceiving the supreme being because of that being's very infinite nature. St. Thomas' argument from degree or gradation, on the other hand, helps the philosopher to come closer to an understanding of God and his existence because it does not require the one considering the question to fail in order for the point to be proven; instead, the philosopher can understand by analogy that though he cannot conceive of the uttermost being of truth, he can accept—from observable reality and the use of human reason—that such an uttermost definition of truth necessarily exist.
Despite the strength of St. Thomas' fourth way over against St. Anselm's ontological proof, it still suffers from what arguably is a deficiency not shared by the other ways: it is difficult to describe a standard for what it is to be “true,” “good,” or “beautiful.” Though a philosopher can describe something as true, good, or beautiful, there is not an empirical standard by which these three categories can be measured. At the same time, however, this is not to say that this destroys the proof. On the contrary, the argument can be grounded in the philosophical context of the notion of an un-measured measurer: just as in the first proof, where an infinite reversion of movers is philosophically impossible, so too in the fourth proof, the must be within the context of a gradation against an uttermost standard be one who sets the standard in the first place. This un-measured measurer, which corresponds to the philosophical concept of the Form of Good advanced by Plato, is a necessary component of the way of gradation.
The weaknesses of St. Thomas' fourth way, even with respect to St. Anselm's ontological argument, are brought to light in the thought experiments posited by the twentieth century philosopher Brand Blanshard. Blanshard asks his interlocutors to imagine a rabbit caught in a trap and to evaluate the philosophical ethics of the situation. He argues that one's relief in finding the rabbit to be released from the trap demonstrates that there is such a thing as objective ethics. This undermines St. Thomas' implications in the fourth way, because it requires that a standard be considered without reference to the uttermost being. Indeed, for Blanshard, despite his protestations to the contrary, the so-called “objective” feeling that determines for him the non-subjective nature of ethics is based upon the experience of the person who considers the rabbit's fate in the thought experiment. In a way, then, Blanshard's argument to “objectivity,” is really more an appeal to collective subjectivity that he posits is shared by all. Blanshard's argument regarding mistake is also based in collective subjectivity. By arguing that it would not be unethical to not feel relief at the rabbit's escape if the rabbit had never truly been trapped or injured since the rabbit had never actually suffered, Blanshard once again opposes St. Thomas' fourth way in favor of a collective subjectivity: since Blanshard's theoretical “everyman” would feel relief even where none is necessary or warranted, such relief is objectively true and good. For St. Thomas, on the other hand, the degree of goodness or truthfulness inherent in the situation described in Blanshard's thought experiment is not related to the observation by the one proposing the experiment; rather, it is based solely on a rational assessment of what the situation actually is.
The conflict between St. Thomas' fourth way and the collective subjectivity that has been argued is present in Blanshard and the incongruence of St. Thomas' methodological insights into God's existence found through the fourth way in contradistinction to St. Anselm's ontological argument are further clarified through the parable proposed by the late-twentieth and early-twenty-first century British analytic philosopher Antony Flew. In Flew's Parable of the Gardener, to persons—a believer and a skeptic—discover what appears to be a well-tended garden on a hike in the wilderness. The question before the two explorers is whether the apparent garden occurred naturally or is tended by a gardener. In Flew's parable, the gardener serves as a stand-in for God, and the two characters' arguments reflect those made by both theists and skeptics. The theist is said to bear the burden of proving that a gardener exists, because the empirical evidence present—according to Flew's argument—precludes a gardener. This is further said to be similar to the problem of the believer in God: that believers must bear the burden of proving that God is real and that despite a “lack” of empirical evidence that it can be shown by reason that God exists. Flew's position is that in proofs such as St. Anselm's and St. Thomas' fourth way there is an assumption on the part of the philosophers conceiving the proofs—who are, themselves, theists—that God exists. The proofs take this theistic assumption as granted and use it to their advantage to argue their theories. Flew states that believers are so thoroughly seeped in their theistic worldview that they can almost not avoid to take this God-drenched paradigm into their considerations.
In a way, then, Flew is arguing that the theists—St. Thomas in his fourth way and St. Anselm in his ontological argument—are being betrayed in their effort to posit a reason-based proof for God's existence by the very collective subjectivity which Blanshard tries to to use as a definition for objectivity. In the theists' case, the collective subjectivity is presumes that supernatural things, which have never been observed or empirically detected, are real. Thus the flaw, Flew would argue, is that the burden should rest on the theist to justify, through reason, a worldview which allows for non-materialistic, non-empirically detectable reality. Neither St. Thomas nor St. Anselm can deliver their proofs for God's existence without relying on some assumption of supernatural possibility. In this way, neither philosopher can effectively address the question within the boundaries set by Flew. But is Flew's bar set too high? Should the philosophers have to prove their points without any recourse to the supernatural at all?
It would seem that even though it cannot be objectively or empirically shown that there are supernatural elements of reality, Blanshard's collective subjectivity—the vast majority of human persons throughout space and time—would support the existence of a supernatural actuality. If this can be granted, however, then both St. Thomas' fourth way and St. Anselm's ontological argument are effective means of bringing a skeptic to the gateway of belief in God's existence. As has been argued already, however, no proof can actually prove God's existence absent his empirical impact on the world in a way detectable by scientific instrumentation. In the end, belief in the Christian God does require what Bl. John Paul II called fides et ratio—faith and reason. Because while reason can bring a person far enough to accept belief in a generic, general god by a preponderance of the evidence, it is necessary for faith—faith in assumptions about reality and faith in divine revelation—to play a role in the believer's coming to a full acceptance of Christian truth-claims made by men like St. Anselm and St. Thomas Aquinas.