Causality, Determinism, Reductionism, and Scientific Materialism
The basis for a scientific worldview is that things happen for reasons—they are caused. But can chance be reconciled with such a scheme?
Our western scientific worldview arose within the context of western philosophy going back to the ancient Greeks, so this is where I start this inquiry. Greek philosophers recognized that chance and lawfulness seem to conflict. This issue was also bound up with the ideas of an intelligent, eternal Creator and the immortality of the human soul.
The Epicureans took the pragmatic (and materialistic) view that neither a Creator nor an immortal human soul exists. Their explanation of how the world arose is remarkably Darwinian. It also includes the evolution of human culture. As to the human soul, Epicureans maintained that it is made up of soul atoms—far more rarified than the more massive atoms that make up our bodies. And, just as our bodies disperse into their elemental parts upon death, they said, so do our souls. Stoics and Platonists (and perhaps Aristotelians) disagreed.
In late Roman times, Boethius had little sympathy with Epicureanism. He tried to synthesize the ideas of the giants of Greek philosophy—Plato and Aristotle—in support of a Christian worldview. He took aim at the old, pagan idea of the goddess Fortuna (who just did things, with no rhyme nor reason). No such power could exist, he said, in a world created by an omniscient, omnipotent God. Thus he saved causality—that things happen for reasons.
But Boethius stopped short of determinism—that God makes you do whatever you do. Clearly, he said, God knows all, so he knows the future, including everything that you will ever do. And, being omnipotent, God could make you do what he wanted—if He so chose. Instead, he chooses to give humans free will, so they can make their own choices. His seeing your future no more determines your choices than (to use a modern analogy) you watching a football game on TV makes the players score a touchdown. True, you can’t watch a future football game, but that’s beside the point. God’s knowing is neither causal nor deterministic in terms of our actions.
Thomas Aquinas, a medieval Christian Aristotelian, got more specific. God made two categories of things, he said: those that must happen just as he chooses and those that he allows to happen in various ways (though still subject to His general laws). For example, God lays down the laws of physics that give rise to weather and storms as well as the laws of biology that grow a forest, but He doesn’t choose which trees in the forest will fall in a given storm. (So don’t blame God if a tree falls on your house. It did so following natural laws, not because He wanted to punish you.)
But, with the protestant Reformation, determinism made a comeback (and free will fell by the way). Our choices are determined, said Martin Luther, by either Satan or God—and God chooses which souls will belong to whom. This doctrine is a form of religious determinism.
It fell to the Enlightenment thinkers Descartes, Newton, and Locke (and later Kant and Laplace) to grapple with causality and determinism in the newly emerging context of modern science. Descartes laid the groundwork by separating spirit and matter. A devout Catholic, he believed in God, but his god was the maker of a clockwork Universe. God made the clock, wound it up, and let it keep ticking on its own. So all natural phenomena are explicable by natural causes.
But Descartes was no materialist. He believed in a human soul, with God-given intelligence. In fact this was his starting place for our ability to know. Descartes famously said, Cogito ergo sum—I think, therefore I am. But the mental or spiritual had precious little overlap with the physical. Thus, Descartes’ philosophy is know as Cartesian dualism.
Newton (a deeply religious protestant) expanded and provided proof for the Cartesian framework. Newton’s universal laws were indisputable and invariable. The angle of incidence will always equal the angle of reflection. For every action, there will always be an equal and opposite reaction. The gravitational pull between two massive bodies will always be inversely related to the square of the distance between them, in relation to their masses.
So causality was a pillar of Enlightenment science. By the time of Laplace (in the Industrial Era), so was determinism. Laplace said that—if one were given the details of all the matter and forces at the beginning of the universe (what we now call the Big Bang)—one could, in principle, calculate everything that happened up to the present, and so on into the future.
In this assertion, the assumption of reductionism is also implicit. Things that happen on a large scale are the sum of many more things happening on smaller scales. Therefore all occurrences in the unfolding universe are ultimately reducible to the motions of bodies relative to one another (all following the laws of Newtonian physics).
But scientific determinism hit a significant blip in 1900. French mathematician Henri Poincaré won a competition to solve the “3-body problem”—but he didn’t solve it. The 3-body problem was physicists’ inability to expand Newton’s gravitational equations from accurately describing the gravitational attraction between two bodies to doing the same for more than two bodies (three being the simplest such case). Poincaré demonstrated that the problem was, in fact, mathematically insoluble. The best one could do was to make approximations. Moreover, it was possible that, very occasionally, something wildly unexpected might transpire.
In retrospect, Poincaré was laying the groundwork for complexity theory, which describes highly interrelated systems whose behavior is causal but not deterministic. Newton’s mechanics work splendidly for mechanical systems—but not for complex ones.
1900 was also when Max Planck proposed quantum theory. And, five years later, Albert Einstein described special relativity. Later he introduced general relativity, which improved upon Newton’s laws of gravity. Newton had never been able to explain how gravity’s “action at a distance” worked. Einstein posited that very massive bodies actually warp the fabric of space-time, causing nearby bodies to begin spiraling towards them.
As transformational as Einstein’s findings were, quantum mechanics (as developed by Niels Bohr, Werner Heisenberg, and others), posed the greater challenge to determinism—and even to causality. The quantum world seemed to be acausal. Sub-atomic particles could pop into and out of existence (coming from and disappearing back into the background quantum field), for no particular reason whatsoever.
Moreover, the boundary between observer and observed became fuzzy. Observers of light could detect it as particles (photons) or waves, depending on the measurement apparatus they employed. Before observation, light was potentially both wave and particle, but only after observation did it manifest as one or the other. This brought into question the ultimate nature of reality—was it “out there” or “in our heads”(or some combination of the two)?
The influence of observer on observed was one of Heisenberg’s explanations for his Uncertainty Principle. If, for example, one wished to very accurately measure the position of a quantum particle, one’s ability to accurately measure its momentum diminished—and vice versa. This was a theoretical limitation; it could not be overcome by devising better measurement devices. With Newton’s calculus, both the position and momentum of a cannonball, anywhere along its trajectory, could be precisely calculated. Not so a quantum particle. There would always be a degree of uncertainty about the totality of its behavior.
Einstein objected strenuously to Bohr and Heisenberg’s interpretation of quantum theory—most particularly to its acausal nature. The purpose of science, he said, is to figure out which causes lead to what effects. If effects simply happen for no reason, that’s no longer science. Einstein famously said to Bohr, “God does not play dice.” To Einstein, a random universe was not an intelligent universe, and Einstein believed deeply in a lawful universe, imbued with an intelligence far greater than that possessed by humans. Einstein proposed a series of experiments that he thought would prove Bohr wrong. As each was conducted, it seemed instead to vindicate Bohr’s interpretation. Science had indeed entered an age of uncertainty.
But, even as physics was becoming less deterministic, biological and social sciences were becoming more so. On the one hand, genetic determinism posited that genes are ultimately responsible for behaviors of both organisms and species. This is a highly reductionistic stance (small-scale dynamics dictating large-scale phenomena). At the same time, behaviorism—famously citing studies of rats, trained in various manners—maintained that environmental conditioning was the ultimate determinant of behavior.
This “Nature vs. Nurture” debate was ultimately resolved (in part thanks to twin studies conducted at the University of Minnesota) with a more or less 50/50 split. Nature (genetics) and nurture (environmental influences) were said to combine about equally to determine behavior. But behavior was still determined.
Reductionistic thinking also flourished. Mental phenomena, for example, were said to be completely reducible to brain chemistry and physical exchanges (electrical and chemical) amongst neurons. In fact, many scientists questioned the very existence of “mind,” since all mental phenomena were explicable in terms of the activities of the physical brain.
This view is also an example of the ascendancy of scientific materialism. For the ancient Greeks, as well as the medieval philosophers, mind or spirit was more primary than physical nature. Even the founders of modern western science (such as Descartes and Newton) upheld the primacy of spirit, though they saw the spiritual as separate from the physical. But, especially in the latter part of the nineteenth century and the first half of the twentieth, the physical world came to be regarded as the only world.
However, in the last fifty years or so, the pendulum has begun to swing back a little. The new field of epigenetics has emerged as a sort of middle ground between genes and environmental factors. While environmental stressors don’t directly change the genes themselves, they can cause genes to be “switched on or off.” Moreover, the “settings” of these “switches” can even be passed on, from one generation to the next (as famously demonstrated by a study conducted on Holocaust survivors and their children).
There are two ways to interpret epigenetic findings. One would be to say that behaviors are still determined, but now in a 3-way split amongst genes, the environment, and epigenetic factors. Another way would be to observe that not all the children of Holocaust survivors have the same “switch settings” as their parents. So determination is too strong a word (though causality would still apply).
Complexity theory, however, may represent the strongest challenge to determinism. The dynamics of complex systems do behave causally. Certain inputs tend to produce particular outputs. However, complex behaviors are inherently unpredictable—though they can be probabilistically forecast with accurate models, as in weather forecasts. Note that quantum behaviors can also be probabilistically predicted. The difference is that quantum laws only apply to extremely small phenomena (such as photons/light and electrons/electricity), while complex systems exist at all scales.
Complexity certainly challenges reductionism. The essence of complexity is that, the properties of the whole are more than the sum of the properties of the members. Therefore the dynamics of the whole cannot be reduced to the dynamics of the parts.
The characteristic of emergence in complex systems may also challenge scientific materialism. What emerges in the whole is qualitatively different than what exists in the parts. In applying this view to the mind-brain controversy, one might assert that mind is an emergent property that is based upon brain but is qualitatively different. Simply put, the mental is not reducible to the physical but it exists nonetheless. However, integration is also key to complexity, so a complex view of mental and physical cannot hold them apart, as Cartesian dualism did.
Under any interpretation, complexity is a watershed science. Most of the systems that influence our lives (including all biological systems and all human social systems) are, by definition, complex. So the fact that the dynamics of these systems are casual but non-deterministic is highly pertinent. However, most people are still steeped in a linear, Newtonian view of the world—one that is highly deterministic. The “modern scientific” worldview we tend to see the world through is more than a century out of date. The study of complex systems allows us to develop a new way of thinking—one that is integrated rather than reductionistic—that can better inform our view of and interactions with the world.
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