A central tenet of theist and especially Christian beliefs is that people have agency; that is, moral choice and therefore moral responsibility, based on a moral Authority outside themselves. The modern view of reality, however, is that there is nothing beyond matter in motion governed by laws of physics, and therefore no God, and therefore no authority beyond our own. Our moral choices—indeed, all our choices, moral or otherwise—are therefore predetermined. That is, the actions of a person at any given moment are the result of the sum of all the movements of atoms from the dawn of time, and not the sovereign choice of the individual.
In fact all events are believed to be thus predetermined. At the dawn of the Enlightenment, certain thinkers took the revelations of Newtonian physics as being proof of determinism—the idea that all that we observe is the result of a series of physical causes and effects stretching back indefinitely. Though he himself strongly acknowledged God, Newton ushered in a revolution in thinking of the universe as being mechanistic.
One who early on appreciated the deterministic implications of Newtonian physics was Pierre-Simon Marquis de LaPlace, 1749-1827. He famously responded to Napoleon’s question why his book on celestial mechanics made no mention of God, by saying “I have no need of that hypothesis.” One could attempt to invoke an innocent meaning to those words, because after all much of what we observe in the material universe does operate mechanistically. LaPlace might have been understood to be limiting his comments to the workings of the inanimate universe without attempting to explain the first causes of physical phenomena. But there is a reason that this exchange is famously imputed to him, and it must be that Napoleon’s sycophants were eager for explicit renunciations of God by well-regarded scientists.
And LaPlace did in fact hold to a deterministic worldview. To the question “What determines what will happen next” he would respond “the state of the universe right now.” This sounds innocuous, at first blush, but the implications are large. Whatever is about to happen, whether an apple falling from a tree or an asteroid slamming into the earth, is determined by the combination of all the events immediately preceding that moment. The apple and the asteroid must fall, given the preconditions for their falling. Just as the pistons of an engine fire in a preconfigured pattern, so every physical event in the cosmos occurs because of the combination of all events preceding it. The entire universe is preconfigured, in that sense. That means not just apples and asteroids, but human beings—their movements, moods, sentiments, emotions, motivations, and conduct.
It must be said, then, that in this deterministic view of reality, there can be no moral choice. Now we can certainly do things we call “good” and “bad” morally, but those are characterizations we impute, presumably because of our evolved biology, not something that inheres in the action itself. If we are kind to someone in a situation in which we have no hope of reward, it is because we are socially conditioned to do so, and we are socially conditioned to do so only because as a species we have evolved to have certain society-enhancing traits, which are self-reinforced by social approbation. There is not really a moral component to what we do. Morality is just a social construct. It is what ardent determinists would call an emergent property of matter.
One way that atheist materialists try to get around this uncomfortable point of their worldview is to suggest that people are way too complex to be deterministic like, say, the movement of planets in the solar system. But that’s just a dodge. That presents an issue of predictability, not a refutation of determinism. There may be a very very large number of vectors explaining the conduct of a complex machine like a human, but the number is still finite. Of course there are more variables involved in a human’s decision-making than in the movements of planets or of specified subatomic particles. But the underlying principle is the same: everything that happens—everything, including what appears to be human volition—is explainable by the state of the universe immediately before.
Pretty bleak, to think of ourselves as being only tiny cogs in a giant machine, with no real decision-making on our own. Nothing we do is really by choice. We have no agency. And nothing we do is “good,” because if there is no agency, that includes moral agency. On the other hand, we’re off the hook for doing the evil we’re pre-programmed to do.
Sure, we can reject all the manifold evidences of God, and believe, like LaPlace, that “we have no need for that hypothesis.” But before doing so, we should think about what principles we embrace, like determinism, rather than just what we reject. If we exclude God from our assessment of reality, then that leads inexorably to the conclusion that everything, including all the wonder and awe and emotion and love and all the other mysteries of the human heart, is an inevitable extrapolation of physics, and nothing more.