The technological marvels and medical advances that the empirical sciences and modern engineering have made possible are truly impressive, and they have, without question, improved the physical lives of countless numbers of people all over the world in the last couple of centuries. Despite the dangers and pitfalls that accompany these advances, it seems undeniable that modern science has improved the physical conditions of human life. Indeed, my ability to bring these musings to you—and your ability to consider them—are themselves only made possible by such advances in science and technology.
But with an appreciation for the goods delivered by science, there has also arisen an anti-religious tendency among those who laud science and scientific advances. In the last few decades especially, it has become commonplace in American culture to suppose that the rise of science came at the expense—and to entail the abandonment—of belief in the existence of God and any non-physical reality such as the spiritual human soul. In place of belief in anything spiritual existing beyond what is physical, many people, especially influential scientists and philosophers, adhere instead to the alternative reductionist worldview of scientific materialism (also known as naturalism or reductionist physicalism).
Scientific materialism or physicalism claims that all that exist are physical objects, the ultimately atomic (or subatomic) particles that compose them and to which they can fundamentally be reduced, and their physical, observable, and measurable forces and properties. This view of the world has the core conviction that science, in specifying the material constituents of which everything—including living things along with ourselves—is composed, has (or in principle can) discover and provide a complete explanation of everything there is in purely material terms.
For instance, noted philosopher of mind Paul Churchland provides what, for him, apparently is the most conclusive argument in favor of physicalism: “the argument from evolutionary history.
"What is the origin of a complex and sophisticated species such as ours? What, for that matter, is the origin of the dolphin, the mouse, or the housefly? . . .[S]ome three billion years ago, we find a trunk of just one or a handful of very simple organisms. These organisms like their more complex offspring, are just self-repairing, self-replicating, energy-driven molecular structures. (That evolutionary trunk has its own roots in an earlier era of purely chemical evolution, in which the molecular elements of life were themselves pieced together.) For purposes of our discussion, the important point about the standard evolutionary story is that the human species is the wholly physical outcome of a purely physical process. . . . Our inner nature differs from that of simpler creatures in degree, but not in kind.
If this is the correct account of our origins, then there seems neither need, nor room, to fit any nonphysical substances or properties into our theoretical account of ourselves. We are creatures of matter. And we should learn to live with that fact.—Paul Churchland, Matter and Consciousness
According to this physicalist view, human beings, like everything else, are exclusively composed of and reducible to their material constituents and the necessary physical laws that govern their interactions and behavior. Indeed, scientific materialism encompasses the more expansive yet fundamental claim that all that exists at all are physical things, their properties, and the necessary physical laws that govern and describe their past behavior and invariably predict their future behavior. Nothing beyond the material world and its elements is believed to be required, nor even allowed, since scientific materialism presupposes completeness and adequacy of its physical explanations.
John Searle, for example, ends his book Minds, Brains and Science (Harvard University Press, 1984) by explaining how this physicalist understanding of human action (including the action of thinking) plays out.
Our basic explanatory mechanisms in physics work from the bottom up. That is to say, we explain the behaviour of surface feature of a phenomenon such as the transparency of glass or the liquidity of water in terms of the behaviour of microparticle such as molecules. And the relation of the mind to the brain is an example of such a relation. Mental features are caused by, and ultimately realized in neurophysiological phenomena. . . . But we get causation from the mind to the body, that is we get top-down causation over time because the top level and the bottom level go together. So, for example, suppose I wish to cause the release of the neurotransmitter acetylcholine at the axon end-plates of my motor neurons, I can do it by simply deciding to raise my arm and then raising it. Here, the mental event, the intention to raise my arm causes the physical event, the release of acetylcholine—a case of top-down causation if ever there was one. But the top-down causation works only because the mental events are grounded in the neurophysiology to start with. So, corresponding to the description of the causal relation that go from the top to the bottom, there is another description of the same series of events where the causal relation bounce entirely along the bottom, that is they are entirely a matter of neurons and neuron firings at synapses, etc.
—John Searle, Minds, Brains and Science, page 93
This scientific materialist view of life and behavior obviously has implications for the notion of free will, which we can explore in another discussion. For the present, it is enough to note that this reductive physicalist view undermines the very processes that allegedly gave rise to it as a worldview and theory of life and behavior, namely the process of science itself (which, interestingly, still involves free will and moral/epistemic responsibility).
Seemingly unrecognized by, or untroubling to, its adherents and proponents, the determinism inherent in scientific materialism makes a farce of the supposedly privileged human behavior that informs us of its truth, namely empirical science and the very arguments in favor of scientific materialism. For, as physicalists such as Searle and Churchland have informed us, according to physicalism, every event in the world must be the necessary result of the physical properties of things (their ultimate atomic constituent parts) obeying necessary laws of physics and chemistry and the necessity of this physical causality would apply to human beliefs and conclusions which are themselves merely the physical states of the brains of the people who hold them.
These physicalists’ claims, however, fail to fit with how we normally describe and indeed must describe our behavior in terms of meaning, purposes, and logical implications of our beliefs and actions. The reason I want to hold and open my umbrella when leaving the house is that I believe it is raining (and I don’t want to get wet, along with the belief that rain gets things wet unless protected from it). These desires and beliefs, however, would not be consistent with grabbing a broom on my way out into the rain precisely because the meaning, purpose, and logical implications of brooms are different from umbrellas.
The full explanation of my activity cannot be physical alone. The physical action of reaching for, holding, and opening the umbrella is not fully explained in terms of axions firing, the release of acetylcholine, etc. This is because the explanation of my behavior also requires that I have the belief that without an umbrella, I will be wet because I believe rain makes unprotected things wet, but an umbrella protects (me) from the rain. All these reasons for acting and conclusions about rain and umbrellas depend on the semantic content of mental states: the meaning of, and the logical relations between, thoughts of rain, wet, wanting (or not), umbrella, and protection. A purely physical explanation in terms of brain states would necessarily leave this out and provide a false description of my behavior.
As Edward Feser notes, when we entertain the meaning of propositions, as when making an argument or giving reasons for why we do what we do or believe what we believe:
". . . there are logical relations between mental states that partially determine precisely which mental states one will have, if one has any at all. But there seem just obviously to be no such relations between neurons firing in the brain. It would be absurd to say – indeed, it isn’t clear what it could even mean to say – that “neuronal firing pattern of type A logically entails neuronal firing pattern of type B,” or that “the secretion of luteinizing hormone is logically inconsistent with the firing of neurons 6,092 through 8,887.” Neurons and hormone secretions have causal relations between them; but logical relations – the sort of relations between propositions like “It is raining outside” and “It is wet outside” – are not causal. There seems to be no way to match up sets of logically interrelated mental states with sets of merely causally interrelated brain states, and thus no way to reduce the mental to the physical."
—Edward Feser, Philosophy of Mind: A Beginner’s Guide, page 68
This limitation of physicalist descriptions of human behavior becomes fatal to the view when applied to the human behavior of reasoning and making arguments. According to scientific materialism, brain states—like every other physical state—are ultimately the necessary result of physical properties of material things (brains, neurons, neural transmitters, synapse firings) obeying necessary physical laws (brain chemistry). Thus, the brain states that realize or instantiate the conclusion of any theory (including scientific materialism) are the necessary physical result of prior brain states. Concluding brain states (like everything else) are completely described and governed by the physical laws of physics and chemistry. Therefore, brain states that instantiate the conclusion of any theory are not the logical result of the meaning and truth of the premises. That is, the neural instantiations in a person’s brain of any conclusion are not the result of the meaning and truth of the neural instantiations of the premises that preceded them in the person’s brain.
According to scientific materialism, at most, the chemically causative properties of premise-making-brain-states that bring about argument-concluding-brain-states may incidentally parallel the logical implications of their semantic content, i.e., what the premises and conclusions mean—though Feser seems to rule out even this incidental parallelism. Such logical implications, at any rate, are not the true, i.e., physical, cause of the concluding-brain state.
And, if the meaning of the premises of an argument (their semantic content) does not provide the true, genuine reasons for holding the alleged conclusion, the argument is either invalid or false, or both.
This is bad news for anyone who thinks that logical arguments provide a good reason for accepting a valid, true conclusion, even and especially physicalist philosophers and scientists who advance arguments for accepting scientific materialism (as Churchland advanced one from evolutionary history above).
Thus, it seems a logical conclusion, if not a physical necessity, that if physicalism is true, the premises of any argument never provide the reason a person holds to their alleged conclusion; brain chemistry is the true, i.e., physical reason a person believes a conclusion. Thus, if physicalism is true, physicalism (and every theory) is false or at least irrelevant.
It just seems obvious, however, that theories and arguments do (or at least should) logically cause what and why people believe what they believe by convincing them. There is even a role for freedom to play in logical, mental activity, for indeed, part of being convinced by an argument is choosing to accept that the premises are true and the conclusion validly follows from them and that one has an obligation to (which implies freedom not to) accept the conclusion as true. As Gary R. Habermas & J.P. Moreland explain:
"Given certain evidences, I “ought” to believe certain things. . . . It is self-refuting to argue that one ought to choose physicalism . . . on the basis of the fact that one should see that the evidence is good for physicalism. . ."
—Gary R. Habermas & J.P. Moreland, Beyond Death, page 65
The fact that it undercuts the validity and truth of all argumentation, including its own, is enough to show that scientific materialism cannot be true. Scientific materialism allegedly bases itself on the success of science in explaining things without the need for God or anything spiritual like the rational human soul. But since it cannot even explain the success, reliability, and truth of itself as a mental process or activity, it utterly fails to justify its claim that God or the soul are irrelevant to an accurate understanding of the world. None of this proves that God is real. This argument, and others like it, just show that scientific materialism has not proven that there is no God and no spiritual soul, but instead, it relies on some process that goes beyond the physical.
For a more complete treatment of this and other problems inherent in scientific materialism, you can read about them here.