In my last post, I introduced the millennial debate on order in the universe. Is the universe fundamentally ordered or chaotic? If it is ordered, do we have the ability to understand that order? Such questions must lurk at the base of any epistemology, any systematic way of knowing, so they will apply equally to science and theology. Can the world be known?
Plato thought the underlying order of the world rested in the eternal realm of ideas, a place dimly remembered from before our birth. For him, certain knowledge was available through our memory and through the immortal part of us that perceives immortal knowledge. Aristotle had a related view that we had access, through our souls to the forms that were the essences of real things. The Stoics and Epicureans on the other hand felt that all our theories must come only through our senses, and thus they were more skeptical of our ability to have certainty.
For the most part, Medieval Christian philosophers believed the world was ordered by God, but they disagreed on how that process worked. Drawing on Margaret Osler’s book, Divine Will and the Mechanical Philosophy, I’m going to set forth the competing positions of Thomas Aquinas and William of Ockham that set the stage for the origins of modern science.
We must begin with a question of human reason. How do we know things? Aquinas, following Plato and Aristotle, thought we had two inputs. Our senses respond to the changing physical world and bring us shadows of reality. The senses are a function of the (mortal, physical) animal soul or, for us, an aspect of the human soul. Our intellect responds to ideas and brings true perception of eternal truths. The intellect is a function of the (immortal, transcendent) rational or human soul. Only a perfect vessel (immortal soul) could hold perfect concepts, or as Aristotle called them, universals. Universal categories contain groups of things we experience (human, cat, table, white) and have essences that apply to all members of the group (e.g., humans are rational mammals). The intellect processes both sense data and universals and stores accurate statements about the world.
Moving on the question of divine power, Aquinas differentiated two types. On the one hand was God’s absolute power (potentia Dei absoluta). This involves God’s utter freedom in setting up the laws by which the universe operates. God could have done this in any way. On the other hand was God’s ordained power (potentia Dei ordinata). This involves God’s restraint in interacting with the universe only according to the established laws.
“Intellectualists” like Aquinas thought that the scope of ordained power was radically less than the scope of absolute power. Whether from logical necessity or personal restraint, God without deviation follows the rules, what we would now call laws of nature. [Note Aquinas used both “law” and “nature” far differently.] Some of the primary rules had to do with the universals. It was, Aquinas thought, essential that humans be rational mammals. God could not make a human otherwise, because rational and mammal were thought “necessary” to humanity.
“Voluntarists” like Ockham held a different view. Ockham had a lower opinion of the intellect in both God and humans. Ockham was unwilling to give up on miracles and wanted to ensure a theology in which God could always act according to the divine will (Latin voluntas). Neither eternal necessity nor God’s previous commitments in Creation could stop God from acting in any way at all. Ordained power is as great as absolute power; indeed, he thought there wasn’t much of a difference. [Ockham did think God could not create a contradiction – for example making something simultaneously exist and not exist – but that was the only limit he saw.] In the whole cosmos, only God is necessary; everything else is completely and eternally contingent on God’s sustaining power.
The range of thought was much greater than these two, with Peter Abelard being one of the most extreme intellectualists – he thought an order existed higher than God – and Peter Damien among the most extreme voluntarists – he thought God set even the rules of logic and contradiction and could do anything at any time.
For Aquinas, perfect knowledge was available through the intellect prior to any observation. To understand the laws of nature was literally to read the mind of God for it meant your intellect had grasped an element of order established in the Divine intellect at creation. Science was all about reading the mind of God. Observations stimulated the process, but much could be reasoned out by reason alone.
For Ockham, we must use our senses and generate probable (uncertain) knowledge based on the regularity of appearances. To understand the laws of nature was to make models of reality that best accounted for the sense data we have. Curiously, it is this defense of omnipotence by a theologian that leads to a central tenet of modern science – you must observe before you can understand. Ockham thought God’s unpredictability required us to be humble in our assertions. We can only model, we cannot “know” in the classic sense.