In the last article, we saw how William of Ockham developed his nominalist philosophy in the context of disputes within the medieval Franciscan order. Ockham’s nominalism—the thesis that there are no real, abstract universal concepts, but that these terms refer only to ideas that we have—undercut Aristotelian arguments about the naturalness of property ownership, based as they were on the assumption that abstract universals such as “human,” and therefore some such thing as “human nature,” really did exist. If there is no such thing as an essential human nature, neither can there be any such thing as certain, permanent, a priori knowledge, on the model of geometry and as advocated by Plato, about how humans ought to live, including the propriety of property ownership. So nominalism strengthened the hand of the Franciscans who wanted a more austere, poverty-embracing way of life, against the popes, bishops, and their allies in the Dominican order, who thought that the naturalness of owning property could be deduced from self-evident truths about human nature. If there was no human nature, those “truths” were not self-evident, but only names. There were many other facets to this discussion, but the general idea of nominalism was to attack these kinds of knowledge claims, those based on abstract, speculative, metaphysical reasoning, which had characterized Western philosophy since the time of Plato.
Nominalism seemed to cut human beings adrift, however. If universals exist, are evident to reason, and can be used as a basis for extracting certain, permanent knowledge, then there is a close connection between the intellect and reality. Getting at truth may be difficult in the sense that one has to put the work in, but it is not difficult in the sense that the concepts of truth, or of knowledge, are in themselves problematic. Some ancient philosophers had taught this, of course, but Plato’s supremacy ensured that it never became the dominant position. For most philosophically inclined people, they would not become problematic again until Hume and Kant raised the specter of skepticism in the eighteenth century. But it was rather the point of Platonic philosophy that certain knowledge was, finally, obtainable. One simply had to define one’s terms, and think carefully about what those definitions entailed.
There aren’t going to be any big surprises with a God who is predictable, rational, and more or less fully known.
But if all our concepts are mere names, as William of Ockham taught, then the kind of knowledge that Plato sought was not available. In a modern context, where reason is the only path to knowledge, this would have entailed some form of skepticism. If reason is all you have, and all reasoning proceeds on names and appearance, then the kind of knowledge that one can expect to acquire is going to be very limited. It might have all sorts of advantages, but it is not going to be “truth-with-a-capital-T,” the certain, final knowledge that Plato and his followers sought. So a certain degree of skepticism is built into a nominalist outlook. In a naturalistic context, and one accommodated to nominalism for so many centuries, this is simply par for the course. But in William of Ockham’s context, where Christian theology occupied a very high station, it could be a truly terrifying idea.
The reason is that Platonism made God intelligible. God was not arbitrary or capricious, according to a Platonic conception, but preeminently rational, and hence knowable. A God that can be known is, in a sense, a safe God. That kind of God produces regular effects in a regular manner, so one’s obligations are clearly spelled out, and one simply has to follow the rules in order to stay in God’s good graces. There aren’t going to be any big surprises with a God who is predictable, rational, and more or less fully known. So, by emphasizing the rationality of God, Platonic philosophy emphasized the reasonability of God, and hence of reality itself. It was a reality where one could feel at home.
But if all concepts are in us, not out there, then what do those concepts mean when applied to God? Their meaning becomes uncertain, so God’s activity and character, too, become uncertain. If, for instance, someone says that God is just or loving or wrathful, then we know what that means by way of analogy to humans. Such a God acts the way humans do when they are just, loving, or wrathful, so there aren’t going to be any big surprises. But if those words do not mean the same thing when applied to God that they do when applied to human beings—after all, the concepts are in us, and don’t necessarily refer us to anything real in the world, let alone in God—then what do they mean? Well, they could mean anything. Perhaps God’s love is very different than human love. Perhaps God’s justice and wrath are very different as well. So there was a danger in the nominalist worldview, that concepts would become detached and uncertain in a way that, on the Platonist worldview, they were not.
Where Thomas Aquinas, following Aristotle, emphasized God’s rationality and omniscience, William of Ockham emphasized God’s freedom and omnipotence. “God is no man’s debtor,” Ockham frequently said, meaning that He is not obligated to human beings in any way. God cannot be so-obligated, according to Ockham, because that would constrain His omnipotence, which is a logical impossibility. So God can create a world one day, and uncreate it the next; God can make promises one day, and unmake them the next; God can save this one, and damn that other one, for any reason, or for no reason at all. Thus human beings are never in a position to question God, in Ockham’s view.
The concepts of omnipotence and inscrutability, taken to their logical extremes, meant that God could never quite be trusted.
This conception of God could be a very unsettling prospect. It was made much more plausible during the outbreaks of plague that ravaged Europe continually during the late medieval period. By some estimates, up to a third of Europe’s population was wiped out, and the medical technology of the time was more or less powerless to prevent, or even understand, these deaths. What possible meaning could such events have? It really seemed that God might, out of sheer caprice, destroy anyone at any time for any reason. Under the influence of nominalism, God became less a universal spirit of love, as experienced by the first Christians, but a continual threat to human well-being. The concepts of omnipotence and inscrutability, taken to their logical extremes, meant that God could never quite be trusted. Only a very radical kind of spirituality (the kind that, for instance, might induce someone to join the Franciscan order, and renounce all one’s worldly property) could feel any devotion toward this kind of God.
Ockham’s conception of God had some important consequences for science, however. If the Platonic conception of God was true, then one could reason from God to the world, and from the world to God, because everything happened out of logical necessity. In fact the Roman Catholic Church never entirely embraced this view, since a God who not only could not contradict logic (as most Christian theologians have held), but was positively forced, at all times, to act from logical necessity, would not be free in the sense required to affect any kind of reconciliation or harmony with the Hebraic, prophetic tradition, as contained within the Bible. The Hebraic conception of God is of an emphatically free being, who is in relationship with the chosen people. But if every act of God is logically determined, then how is God free? So the Roman Catholic Church never embraced the conception of God as a being whose every act was logically determined, as Spinoza was to do in the seventeenth century. But it remained the case that one could reason a good deal about God from the state of the world, and the state of the world from what one knew about God. Especially in the Aristotelian, Scholastic philosophy of Thomas Aquinas, the rationality and omniscience of God was definitely privileged over the freedom and omnipotence of God. So a priori knowledge about the world is obtainable, on that view.
Nominalism involves an important shift in the concept of knowledge itself. A priori knowledge doesn’t count anymore
But Ockham’s nominalism called this assumption into question. If God is essentially a volitional, rather than a rational, being, and if God’s omnipotence could have produced a world of virtually any conceivable description, then one could not just sit back and reason about how things must be. One has to go out and look. True, such knowledge will only be partial and provisional, but since that’s the only kind of knowledge that is available in any case, according to nominalism, one can hardly complain about it. So nominalism involves an important shift in the concept of knowledge itself. A priori knowledge doesn’t count anymore.
To give an example of the difference in thinking involved, Bertrand Russell once mocked Aristotle, saying that he “maintained that women have fewer teeth than men; although he was twice married, it never occurred to him to verify this statement by examining his wives’ mouths.” How can something so obvious have escaped the attention of the great philosopher? Well, on the Platonic conception of knowledge, just counting the number of teeth in his wives' mouths would not have gotten to the heart of the matter. All it could have told him is how many teeth were in the mouth of a particular woman. He could have counted all the teeth in all the mouths of the people in his village, and the result still wouldn’t have been knowledge. It would have told him about the teeth in the mouths of particular people, not about human mouths as such. Because, for Plato, the world of sense experience, that where things come into being and go out of being, is not the real world, but only a shadowy reflection of the forms that have true existence, the kind of empirical inquiry that Russell called for could not, in principle, establish knowledge. Real knowledge is about real objects—which is to say, the forms. And it has to be certain, and permanent in character, not mere conjecture. Real knowledge is the kind that we have about triangles: they always and necessarily have three sides, and interior angles of one hundred and eighty degrees, not any other number, ever, else it is not a triangle. So if geometry sets the standard for what counts as knowledge, Bertrand Russell’s suggestion that one simply count teeth is not applicable. One first has to have the concept of nominalism in place to think that this kind of procedure is going to produce knowledge. In other words, one has to already be accustomed to the idea that knowledge is only ever partial and provisional, to think that counting particular teeth in particular mouths is going to yield results that ought to count as knowledge. Aristotle didn’t look into his wives' mouths and count their teeth, not because he was ignorant, but because he was not a nominalist.
By shifting the grounds of knowledge, Ockham’s nominalism helped pave the way for modern science: by privileging empiricism (that is, observation and experiment) over rationalism (that is, an emphasis on a priori deduction from first principles); and by encouraging us to think of the provisional and partial nature of the resulting knowledge, not as disqualifying it from the category of genuine knowledge, as Plato held, but rather, as both a humbling and an exhilarating aspect of our pursuit of it. It is humbling, because one has to be willing to think of the knowledge that results as always open to future revision, so one can never be quite certain that one has laid a hold of truth. And it is exhilarating, because it means that the voyage of discovery is, in principle, without end.
This essay is part of a series; the previous essay can be found here.
Daniel Halverson is a graduate student studying the History of Science and Technology. He is also a regular contributor to the PEL Facebook page.