From the Causal System to Parallelism
These principles gave me a natural way of explaining the union of the soul with the organic body, or rather their conformity with one another. Soul and body each follow their own laws; and are in agreement in virtue of the fact that, since they all represent the same universe. There is a pre-established harmony among all substances. (Leibniz, 1714, Monadology, 78, p. 10)
According to the philosopher Edmund Husserl,5 Galileo’s generation also postulated that each event of the universe can be defined in function of fundamental properties that are applicable everywhere: location, space and time, weight, size, and so on. The calculations become possible when the object studied is reduced to an idealizedâ form (sphere, cube, etc.) associated to the properties of the real object (location, weight, size, etc.). Once these properties have been isolated, the physicist can compute how an object can be situated in a causal chain. This type of procedure permits scholars to construct an explanatory scientific system. This vision is monistic and materialistic: the universe is composed of one basic material substance. The relationship between the properties and mathematics makes it possible to sort out the great laws of a causal system that allows one to understand the functioning of the universe. Science would henceforth associate empiricism (e.g., experimental physics) and mathematical theory (e.g., theoretical physics). If one accepts that every particle of the universe obeys these laws, then one also assumes that the thoughts of the mind follow these same principles. Even today, no one knows what the properties of the mind really are. But if we follow this vision, the day when psychologists will be able to isolate the properties of a thought or a sentiment will be the day when it becomes possible to foresee, mathematically, the way these phenomena relate to each other.
Galileo’s absolute formulation leaves little place for God. Some philosophers of the subsequent generation, like Descartes, distinguished a dimension of the universe that effectively follows the scientific laws (matter) and a parallel dimension whose dynamics are distinct, near to those that actuate God (soul):6
1. Matter is everything that the senses can perceive: planets, objects, particles, air, fluids, and light.
2. The soul can perceive and think.