The World Philosophy Made
Page 4
This argument is illuminatingly discussed by Norman Kretzmann in the following passage.
[According to Aquinas] to be a cognitive faculty is to be essentially in a state of receptive potentiality relative to certain types of things, the faculty’s proper objects—such as sounds, for the faculty of hearing. So if the faculty itself has such a type of thing in it actually [i.e., as part of its nature]—such as ringing in the ears—it forfeits at least some of the natural receptive potentiality that made it a cognitive faculty in the first place.… “So if the intellective principle [our rationality] had in itself the nature of any body, it would not be capable of cognizing [understanding] all bodies. But every body has some determinate nature, and so it is impossible that the intellective principle be a body” (Summa Theologica Ia.75.2C).17
In short, the rational aspect of our soul isn’t located in any bodily organ, and does not have to use any organ in order to think. Although the bodily sense organs do supply the human soul with data for thoughts about what is perceived, such data are not required for purely conceptual thought, which can occur without them.18 Aquinas takes it for granted that if the rational soul isn’t located in any bodily organ, then it isn’t located in any material body at all. Thus, he concludes that the rational aspect of the soul of Socrates can exist after the death of Socrates.
But does it exist after death? Presumably it does. Since it was never the (Aristotelian) form of any body, its existence and rational operation was always independent of matter, in which case there is no reason it should cease to exist with the death or destruction of Socrates’s body. Thus, According to Aquinas, the rational aspect of Socrates can still think after the body dies—it can have purely conceptual thoughts—even though it can’t then perceive or remember anything.19
This remarkable argument threatens the Aristotelian metaphysics that Aquinas worked so hard to revive. Aristotelian forms can’t, by definition, exist without informing one or more bodies. Thus the rational human soul that Aquinas postulates can’t be an ordinary Aristotelian form. What, exactly, is it then? This worry is connected to an even more basic problem. Was Socrates himself identical with—i.e., the very same entity as—his rational soul? If so, then he and his soul were one and the same, and, since his soul was never a fusion of form and matter, he was never such a fusion, in violation of Aquinas’s contention that every human being is a composite of body and soul. If, on the other hand, Socrates’s rational soul was not identical with Socrates, then showing it to be immortal (if one could do so) wouldn’t show Socrates to be immortal.
The basis of Aquinas’s response to this dilemma is given in the following passage.
[We] come to know the human soul’s mode of existence, on the basis of its activity. For insofar as it has an activity [rational thought and understanding] that transcends material things, its existence, too, is raised above the body and does not depend on it. On the other hand, insofar as it is naturally suited to acquire immaterial cognition from what is material [e.g., sensory cognition], the fulfillment of its nature clearly cannot occur without union with the body; for something is complete in its nature only if it has [in itself] the things that are required for the activity that is proper to its nature. Therefore, since the human soul, insofar as it is united to the body as a form, also has its existence raised above the body and does not depend on it, it is clear that the soul is established on the borderline between corporeal and separate [i.e., purely spiritual] substances [such as angels].20
This puzzling statement of the borderline character of the human soul and its junction with the body may be the most important, but also most problematic, aspect of the attempted Thomistic synthesis of Christian theology with Aristotelian philosophy.
Following Aristotle, Aquinas took rationality to be the distinctive feature of humanity, which is also, he argued, the respect in which human beings are made in the image of God.21 Echoing Aristotle’s “All human beings desire to know,” he took the human desire to know and understand to be an expression of our deepest nature, which is rooted in the soul. Also following Aristotle, he took human beings to be composites of souls (which were special types of forms) and matter. But since human beings had to turn out immortal for Aquinas (though their bodies aren’t) he had to argue three things. First, as we have seen, he had to argue that human souls can, and do, exist without the body. Second, as we have also seen, he had to argue that they cannot completely fulfill their function (of achieving knowledge and understanding) without a body. Third, he had to argue that nothing can exist forever without fulfilling its proper function, as the souls of dead human beings would do if they were never reunited with their lost bodies.
Aquinas does this in the following passage from Summa Contra Gentiles.
It is therefore contrary to the nature of the soul to be without the body. But nothing which is contrary to nature can be perpetual. Hence the soul will not for ever be without the body. Therefore since the soul remains for ever, it should be united again with the body, and this is what is meant by rising (from the dead). The immortality of souls seems then to demand the future resurrection of bodies.22
This argument, in addition to assuring Aquinas of the immortality of the man Socrates, expresses something important about his conception of the interdependence of human souls and human bodies. Since each is, in a certain sense, equally in need of the other, Aquinas regards individual human beings as genuine unities, rather than immaterial Platonic souls who, when inhabiting bodies, merely use them as tools.23 Having come this far, Aquinas adds that the human desire for immortality must be fulfilled because God wouldn’t give us a desire that can’t be fulfilled. Since divine revelation promises the resurrection of the body, many regarded his argument for the immortality of the soul, and its eventual reunion with the body, as a contribution to his broader reconciliation of faith and reason.
This temporary reconciliation provided Christianity with the intellectual resources of Greek philosophy, which was still the most comprehensive synthesis of knowledge of the natural world. Moreover, it did so without threatening the religion’s role as interpreter of the ultimate purpose of life and the individual’s guide to salvation. Although Thomism had it rivals, the modus vivendi between faith and reason it prompted became one of the lasting achievements of western civilization. A religion based on a mystical interpretation of particular historical events, appealing to every social class, with an ethic of human behavior based on a vision of the meaning of life, had become linked to an epistemological system the goal of which was to use observation, precisely defined theoretical concepts, logic, and mathematics to acquire comprehensive knowledge of ourselves and the universe. The legacy of this display of open-mindedness would be felt for centuries.24
The truce between faith and reason was also a boon to philosophy. By relieving philosophy of the responsibility for discovering the meaning of life and charting a path to personal fulfillment, it allowed philosophy to reclaim its role of advancing evidence-based knowledge in every domain (outside of revealed religion). As Copleston puts it:
Since historically speaking, Aristotelianism … was a production of reason unaided by revelation, it naturally brought home to the mediaevals the potentialities of the natural reason: it was the greatest intellectual achievement they knew. This meant that any theologian who accepted and utilized the Aristotelian philosophy … was compelled to recognize the theoretical autonomy of philosophy.… Looking back … we can see that acceptance of a great system of philosophy … was almost certain sooner or later to lead to philosophy going her own way independent of theology.25
This rebirth of classical philosophy—which would gradually become autonomous, self-critical, and focused on advancing scientific knowledge—was the great gift of Aquinas and other philosophically minded theologians who followed him.
One of these was the thirteenth-century British monk Roger Bacon (circa 1212–1292), whose belief in empirical observation, mathematics, and science coexisted with a conser
vative, even mystical, theology. In his chief work, Opus Maius, he declares it to be philosophy’s purpose to interpret the scriptures and, in all other ways, to lead us to God. Reason, philosophy’s tool, is identified with God, and so must never be despised. Since the function of truth is to lead humanity to God, no particle of truth should be neglected. These ideas led Bacon to science and mathematics, the latter essential to sciences like astronomy. A man of many interests, Bacon took the earth to be spherical and very small compared to the heavens. He also wrote about light, eclipses, tides, the structure of the eye, and the principles of vision. His work on reflection and refraction was devoted to learning how we could make small things appear large, and distant things near. Although he didn’t invent the telescope, he did discover principles that others would use to do so.
Opus Maius also contains a sophisticated discussion of scientific methodology in which reason’s role is to frame hypotheses and deduce observational consequences from them. He took a hypothesis to be refuted if those consequences are false, and he insisted that no hypothesis can be accepted without such testing. Like Aquinas, he used Aristotelian categories in his natural philosophy. But his major contribution to the Thomistic synthesis of faith and reason was his genuinely scientific spirit, not unlike Aristotle’s, which was reflected in the wide range of his empirical interests, the vigor of his investigations of natural phenomena, the clarity of his experimental method, and the practical value he hoped ultimately to be derivable from it.
If we pause at this point to ask What did philosophy contribute to mid-thirteenth-century Christian Europe? we see its contributions in the thought of Albertus Magnus, Thomas Aquinas, and Roger Bacon.
(i) It contributed, through Aquinas, to a view of faith and reason as allies rather than antagonists, thereby introducing a strain of rational theology into Christian thought that had already incorporated Platonic elements from Augustine, now championed by Saint Bonaventure.
(ii) It contributed, again through Aquinas, to a conception of God as a purely rational necessary being, who, by making human beings in the image of God, made them natural seekers of knowledge of what was assumed to be a rational, well-ordered universe.
(iii) It thereby contributed to a reawakening of the scientific spirit of Aristotle, which found expression in the empirical investigations of the natural world by Albertus Magnus and Roger Bacon.
As we move into the second half of the thirteenth century and beyond, we find increasing philosophical ferment, accompanied by a growing intellectual focus on the natural world. One of Aquinas’s immediate successors was the Franciscan theologian John Duns Scotus (1266–1308). Building on, and criticizing, the Thomistic synthesis of Aristotelianism with Christianity, he developed an independent following, while paving the way for more far-reaching departures from Thomism. One of his most consequential departures involved Aquinas’s argument for the soul’s immortality, which presupposed not only that Socrates and Plato were different persons, but also that their souls—the forms of their respective bodies—were different. Since Plato and Socrates were humans, those forms couldn’t have been the single human nature common to all humans. How then did Socrates’s individual human nature differ from Plato’s? According to Aquinas, they differed numerically because they were forms of different quantities of prime matter, but they didn’t differ qualitatively, because no qualities can be attributed prime matter. This thesis was generalized: Matter is the principle of individuation that distinguishes different members of the same natural kind.
Scotus argued that this doctrine, plus the Thomistic thesis that the different souls of Socrates and Plato exist after their deaths, entails that the two souls/forms contain prime matter that individuates them even when they are not the forms of any body. Since this was an Aristotelian absurdity, Scotus rejected the doctrine that matter individuates individual forms. He could have gone further. If Socrates’s soul were the Aristotelian form of his body, but not of anything else, then it couldn’t exist when the body dies or ceases to exist. Although this might seem to threaten the project of reconciling Aristotelian natural philosophy with Christian theology, Scotus didn’t take that step. Christianity was secure because revelation assured him of the immortality of human souls and the eternal lives of persons after the resurrection of their bodies. Consequently, he seemed to suggest, it ought to be possible to construct a synthesis of Christianity and Greek philosophy in another way. Indeed, his philosophy is sometimes taken to be the last such medieval synthesis.26
The critique developed by William of Ockham (1287–1349) was more far-reaching. Though he was a theologian and philosopher, his emphasis on God’s absolute freedom and omnipotence left little room for Greek notions of essence and necessity. Displaying strong logical, analytical, and empirical elements, his highly original philosophy offered no independent confirmation of God’s existence or nature. Nor did it offer independent support for the spirituality of the soul, or human immortality. In part because of this, Ockham’s thought was judged heretical by some in the Church. Among other things, he engaged in Church politics, including a dispute between the pope and the emperor of Bavaria. Despite being excommunicated in 1328, he remained an active intellectual influence until he died of the Black Death in 1349, after which his followers, advancing as advocates of the via moderna, continued their struggle against the via antiqua of Thomism, Scotism, and Augustinianism.
The heart of his critique of Greek metaphysics in Christian philosophy was his denial of universals—common natures of things of the same type, thought of as Platonic or Aristotelian forms. For Ockham, there is no such thing humanity that is common to all and only humans, and no such thing redness common to just red things. There are, of course, individual humans and particular red things plus the words ‘human’ and ‘red’ (and others with the same meanings) that are used to designate them. But there is nothing beyond being so designated that is common to those things—or so it seems until one asks What is the meaning of a general term T used in a predicate ‘is (or is a) T’? The traditional answer is that it is a way that individual things can be. Since it is possible for some things to be human, some to be red, and some to be round, being human, being red, and being round are ways things can be. These ways, it had been supposed, are the meanings of ‘human’, ‘red’, and ‘round’. When one uses a subject-predicate sentence, one represents the thing designated by the subject expression to be the way one’s use of the predicate represents it.
This picture of linguistic meaning presupposes that there are ways things could be. What are they? Denying the existence of Platonic or Aristotelian forms, Ockham says that the meaning of a general term T is a concept C existing only in the mind.27 He adds that when C is the meaning of T, the latter designates all and only things that are similar to each other in the way given by C. But how does this help? If one is puzzled by ways individual things are or could be, one should be equally puzzled by ways pairs of things are or could be similar. Either both really exist or neither does. If you doubt (or accept) that there are ways individual things can be—e.g., being red and being green—you should also doubt (or accept) that there are ways pairs of things can be—e.g., being similar in color to this (said of a fire engine) and being similar in color to that (said of a patch of well-watered grass). Ockham seems to miss this.
He also seems to equivocate. Although he often claims that only individuals exist, he sometimes adds the qualifier “outside the mind.” For example, he denies that relations (presumably including similarity) exist outside the mind. He bases his denial on the claim that all real existing things (outside the mind) are, in principle, independent of all other such things, in the sense that God could have created them independently of whatever else he created. So, Ockham argues, if relations existed outside the mind, God could have created them without creating any objects they relate. Regarding this as absurd, he concludes that relations exist only in the mind.
The claim on which he relies is questi
onable. Consider the relation originating from in which a giant redwood stands to the seed from which it originated, and in which I stand to the particular zygote from which I originated. Is it clear that the first members of those pairs (the redwood and me)—not qualitative duplicates but those very things—could have existed without the second? For that matter, is it also clear that I could have existed even if my biological mother never did, and hence even if I didn’t stand in the relation being her child to her? If these things aren’t obvious, then Ockham’s argument that relations don’t exist “outside the mind” relies on a questionable premise.
Ockham gives another argument for the same conclusion. If, he says, there were relations outside the mind, then when I move my finger, I would change the spatial relation in which it stands to other things, and so change the properties of everything in the universe. He regards this as absurd, but doesn’t say why, or indicate how the absurdity is supposed to be removed by saying the relation exists only in the mind. Surely, for each physically located object x in the universe, it ought to be possible to construct a spatial predicate relating x to my finger that is true of x before I move my finger, but not after, and another predicate that will be true of x after I move my finger, but not before. Since to say this is just to say that certain things are true of x before I move my finger that won’t be true after, this should mean that x changed properties. Since this result doesn’t depend on the awareness of any mind, it’s not clear that Ockham’s in-the-mind stipulation does any real work.