This is the second article in my new series exploring the relationship between atheism and various other commonly associated ideas. In the first article, I explore the link between atheism and skepticism. In this article, we look at the relationship between atheism and materialism.
What is the relationship between atheism and the philosophy of materialism? The close association between atheism and materialism is evident in Christopher Hitchens’ edited volume The Portable Atheist: Essential Readings for the Nonbeliever which includes as its first entry a collection of excerpts from the great Roman philosopher Lucretius’ magisterial two thousand-year-old poetic work De Rerum Natura (On the Nature of Things). This famous poem provides a sweeping depiction of the ancient Greek materialist’s vision of reality. Lucretius begins,
For ‘tis high lore of heaven and of gods that I shall endeavour
Clearly to speak as I tell of the primary atoms of matter
Out of which Nature forms things: ‘tis “things” she increases and fosters;
Then back to atoms again she resolves them and makes them to vanish.
Later he adds the following bucolic vision:
Secondly, why do we see spring flowers, see golden grain waving
Ripe in the sun, see grape clusters swell at the urge of the autumn,
If not because when, in their own time, the fixed seeds of matter
Have coalesced, then each creation comes forth into full view….
With these two elevated poetic passages, Lucretius is painting for us a picture of the world in the terms of the Greek atomists, a world in which all the things we encounter from blooming flowers to fulsome golden heads of grain are borne of the atoms that make up all things. As nineteenth-century poet, Percy Bysshe Shelley described it in the poem “Hellas,”
Worlds on worlds are rolling over
Like creation to decay
Like bubbles on a river
Sparkling, bursting, borne away.
In one sense, Lucretius’ materialist vision of nature being wholly composed of atoms is striking for its marginalization of spirit forces and in that sense it appears to offer the kind of secularized and skeptical worldview that warrants its inclusion in a book chronicling the intellectual atheist tradition.
More about that aspect anon, but note first that the passage in question is not explicitly atheistic. Indeed, the first passage begins with a reference to “the gods.” Granted, deity has little-to-no religious function in Lucretius’ atomistic vision of reality. But even so, one cannot dismiss the reference as if it is merely perfunctory. The fact remains that deity is not eliminated altogether from Lucretius’ worldview, even if the realm of the gods is placed beyond the horizon of existential relevance.
Lucretius did not originate the tradition he represents. He was a disciple of Epicurus who in turn drew his philosophical inspiration from the Greek atomist Democritus. In his magisterial History of Western Philosophy Bertrand Russell (perhaps the most important atheist of the twentieth century) expressed his view that the Greek atomists like Democritus provided a striking anticipation of contemporary science:
“Their point of view was remarkably like that of modern science and avoided most of the faults to which Greek speculation was prone. They believed that everything is composed of atoms, which are physically, but not geometrically, indivisible; that between the atoms there is empty space; that atoms are indestructible; that they have always been, and always will be, in motion; that there is an infinite number of atoms, and even of kinds of atoms, the differences being as regards shape and size.”
The atomists had their internal disagreements regarding issues like the precise nature and movement of the atoms (which they believed to be the fundamental constituents of reality), but they shared a commitment to determinism in which all events were governed by natural laws. In Russell’s estimation, “The theory of the atomists, in fact, was more nearly that of modern science than any other theory propounded in antiquity.”
My concern here is not with the accuracy of Russell’s description of Greek atomism or the degree to which the atomists may have anticipated a contemporary scientific view of the world. (However, while we’re on the topic, it should be said that the deterministic world of Greek atomism looks like a more natural fit with pre-Einsteinian science than the world of quantum and chaotic indeterminacy that is the current picture in science. ) Rather, my point is that modern atheists like Hitchens and Russell see a close association between their own atheism and a materialist tradition that extends back more than two millennia.
Naturalism and Physicalism
It is important to recognize that while Greek atomism may seem dated, materialism itself is not a relic of the past. In fact, it lives on even now within the academy, although these days one is more likely to find it identified under a label like naturalism or physicalism.
The definition of naturalism is much disputed. Or perhaps a better way to put it is that there are distinct concepts at play that share the same name. In some instances, naturalism refers to the view that nothing exists beyond nature and that nature is a closed system. Others define naturalism explicitly in terms of the end goals of science, i.e. as the view that whatever exists is that which will one day be defined by a completed natural science. Under this guise, naturalism merges with another concept, scientism, which we will discuss momentarily.
Fortunately, the term physicalism is easier to define. Daniel Stoljar states that “Physicalism is the thesis that everything is physical, or as contemporary philosophers sometimes put it, that everything supervenes on the physical.” Clearly, there is significant overlap between classic materialism and contemporary naturalism and physicalism. All these views affirm that existence is somehow to be understood in terms of nature and natural science.
Reductive and Non-Reductive Materialism
Let’s hone in for a moment on one aspect of Stoljar’s definition, namely the reference to non-physical entities supervening on the physical. Just what is this supervenience relationship exactly? To answer that question, we can begin with the fact that many forms of classic materialism are reductive. That is, they aim to reduce all existence to the material. To illustrate, think of the world as akin to a photograph of a crowded summer beach with hot sand, rolling surf, puffy clouds on the horizon, and hundreds of umbrellas, beach balls, towels, and swimmers. Now move in closer and focus on a portion of the photograph. As you continue to focus in, eventually the particulars of the image disappear as the scene blurs into patterns of tiny pixels, each one composed of a red, green, and blue element. Just as the image of the photograph is reducible to the pixels, so, in this reductive picture, the world around us with all its diversity and complexity is reducible to fundamental physical constituents, atoms in the classic Greek picture. Reductive materialists believe something like that is true of the universe. Even something as seemingly irreducible as consciousness, composed as it is of intentional thoughts, sensations, and emotions, is nonetheless believed to be reducible to material constituents much like the picture is reduced to pixels.
While some philosophers still accept the reductive picture, others believe that various aspects of reality and consciousness, in particular, are not reducible to physical constituents in the way the picture is reducible to the pixels that compose it. Instead, they insist that reality is complex and layered, with novel, irreducible ontological realities emerging at higher levels of complexity. John Heil writes, “We inhabit a layered world, the characteristics of which present a hierarchical or sedimented appearance.” And that brings us to the concept of supervenience. For many philosophers, the mind-brain relationship has provided the paradigm example of a supervenience relation. Thus, for example, the idea is that physical neurons firing in the (physical) brain give rise to non-physical conscious experience (e.g. tasting spearmint). In that case, the conscious experience of tasting peppermint supervenes on the physical pattern of neuron synapses in something like the way smoke supervenes on a fire. The sensation of tasting peppermint cannot be reduced to the neurons firing in the way the image is reducible to pixels. Nonetheless, the sensation is dependent on the physical pattern of neurons firing.
While the mind/brain relation provides the paradigm example of a supervenience relation, there are many others as well. To note one further example, the property of liquidity supervenes on the molecular structure of hydrogen and oxygen atoms as they comprise H20. In other words, when hydrogen and oxygen atoms combine to form water, the novel property of liquidity supervenes on those atoms. The property of liquidity is a necessary byproduct of the existence of water. Physicalists believe that in a similar way the creation of a brain with collections of firing neurons gives rise to a novel by-product: consciousness. Like smoke rising from a fire, consciousness arises from the functioning of a brain.
When is one a materialist?
There is an important difference between reductive and non-reductive materialist models of the world. And that difference leads one to ask, just what does it take to qualify (or fail to qualify) as a member in good standing of this materialist-naturalist-physicalist tradition? That’s a difficult question to answer because traditions like this inevitably have fuzzy boundaries, and there is no universally recognized magisterium, that is, a teaching authority or a judging panel, to which one may appeal to settle a dispute. Having said that, it seems to me that the materialist tradition can be understood as combining thesis 1 with thesis 2 or thesis 3:
- causal closure thesis: the system of nature is closed to intervention by any outside agent/intelligence;
- weak materialist thesis: everything that exists in nature is material or supervenient on the material;
- strong materialist thesis: everything that exists is material or supervenient on the material.
Can a theist be a materialist?
Having summarized the materialist tradition with these various theses, we can now pause to ask the question of whether theists might qualify as adherents to this materialist tradition. Let’s begin with thesis (1) concerning causal closure. If we turn back to Lucretius we certainly get the picture of nature as a closed system in keeping with the causal closure thesis. At the same time, as I noted, Lucretius allows for the possibility that there are gods beyond this closed natural system. The specific type of theism that affirms God along with a causally closed universe is called deism. According to deism, God brings the universe into existence but he does not engage in discrete action within the universe once it is created.
It is important to recognize that one does not need to go back two thousand years to find an adherent of the naturalist tradition accepting deism. Even today there are naturalists who explicitly take this position. In his book Consilience: The Unity of Knowledge scientist E.O. Wilson provides a dazzling and ambitious defense of a naturalist view of the world. In Wilson’s optimistic view, science may one day achieve a sweeping understanding of a complete closed system of nature ranging from fundamental physics all the way up to the reified reaches of ethics and aesthetics. At the same time, Wilson tentatively retains a place for God (defined in deistic terms) just beyond the border of nature. As he says, “On religion, I lean toward deism but consider its proof largely a problem in astrophysics.” Note that Wilson appears to endorse causal closure.
While we could spend more time exploring the nuances of naturalism and the lineaments of causal closure theism, the lesson for us, as William Dembski rightly observes, is that “Naturalism is not atheism. To affirm that nature is self-sufficient is not to deny God’s existence. God could, after all, have created the world to be self-sufficient.”
Before moving on to the two supplemental materialist theses, it is perhaps worthwhile to point out that some non-deistic theists also accept causal closure. And how might this work? To consider one proposal, Dennis Bielfeldt offers an interesting, if speculative, model in which God supervenes on the material universe and then exercises top-down causation back into it in analogy to human minds acting on human brains. Bielfeldt’s model is clearly intended to offer a way to accept both causal closure and non-deistic divine action in the world. And while the proposal faces significant objections and challenges, one must at least concede that its very existence shows that even non-deistic theists could accept the causal closure of nature. Even if the universe is causally closed, God need not be consigned to existence beyond the outer limits of the cosmos.
Theism, Weak Materialism, and Strong Materialism
Next, let’s consider the relationship between theism and the weak and strong materialist theses. Might one find theists who would support these claims? To begin with, one can find several Christian philosophers of late who have endorsed weak materialism. For example, Nancey Murphy, Professor of Christian Philosophy at Fuller Seminary, has done some important work in developing and defending a non-reductive supervenient model of the world. Non-reductive physicalism (as the view is often known) is actually quite popular today among Christian philosophers and theologians.
Okay, but what about strong materialism? Surely one could not find a theist who is a strong materialist? After all, God is by definition non-physical, is he not? No doubt it is true that mainstream theism is committed to a repudiation of strong materialism. However, that doesn’t change the fact that one can indeed find materialists who are theists. For starters, Mormon theology is built on a materialist metaphysic that construes even the divine being as a material entity. What is more, the great third-century Christian theologian Tertullian was a materialist who conceived of God as a material being. To be sure, Tertullian’s strong materialism is highly idiosyncratic relative to the wider Christian tradition. But idiosyncratic though it may be, the fact remains that it is at least possible for a theist (and even a Christian theist) to be a strong materialist.
To sum up, theism is consistent with the great tradition of materialism as evidenced in the fact that theists can endorse (1) the causal closure thesis, (2) the weak materialist thesis, and (3) the strong materialist thesis.
Atheists Who Reject Materialism
This brings us to another important point. Just as a theist could accept materialism, so an atheist could reject it. And indeed, some high profile, respected atheists do precisely that. This brings us to the case of Thomas Nagel, the University Professor of Philosophy and Law Emeritus at New York University. While Nagel has been outspoken about his own atheism, he is also among the most persistent and effective critics of materialist or naturalist accounts of reality. Nagel provides his critique of naturalism as well as his counter-proposal in his book Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature is Almost Certainly False. Nagel is driven in particular by the mind/brain problem which he believes presents an irresolvable problem for conventional models of materialism/naturalism. Since he is an atheist, Nagel also repudiates theism. But in his view, there is an unexplored middle territory between theism and naturalism and it is this territory that Nagel stakes out for his own view.
And just what is that territory? Nagel suggests the possibility of a panpsychic view in which consciousness is fundamental and ubiquitous in the cosmos. As he suggests, “Everything, living or not, is constituted from elements having a nature that is both physical and nonphysical—that is, capable of combining into mental wholes. So this reductive account can also be described as a form of panpsychism: all the elements of the physical world are also mental.” In this way, Nagel seeks an explanation for life, consciousness, reason, and knowledge which depends neither on divine action (as in theism) nor as accidental by-products of laws of nature but instead as “an unsurprising if not inevitable consequence of the order that governs the natural world from within.” Nagel recognizes that this proposal is “unorthodox” relative to the naturalist tradition, but he is nonetheless compelled by the evidence as he sees it, to explore this otherwise idiosyncratic position.
Here we find ourselves at the tip of an iceberg of debate. The takeaway point for us is simply that Nagel presents his view precisely as an atheist who is dissatisfied with the prospects of the venerable naturalist tradition that traces back to Lucretius and the Greek atomists. So the irony is that theists may accept and work within the materialist/naturalist tradition while atheists like Nagel explicitly reject it.
 Lucretius, “From De Rerum Natura (On the Nature of Things),” trans. W. Hannaford Brown, in Hitchens, The Portable Atheist, 2.
 Lucretius, “From De Rerum Natura (On the Nature of Things),” 4.
 “Hellas,” The Complete Poetical Works of Percy Bysshe Shelley (Boston: Houghton Mifflin, 2009), 325.
 Bertrand Russell History of Western Philosophy (New York: Simon and Schuster, 1972), 65.
 Russell, History of Western Philosophy, 66.
 The word atom comes from the Greek work atomos meaning “uncut” or “indivisible.” Since scientists split the atom the journey to understand the most fundamental constituents of material existence from protons, neutrons, and electrons on to more exotic subatomic particles and beyond. This transition calls to mind the old adage, he who marries the science of the age is soon a widower
 For further guidance on the definition of naturalism see Kelly James Clark, ed., The Blackwell Companion to Naturalism (Malden, MA: Wiley, 2016); David Papineau, Philosophical Naturalism (Oxford; Cambridge, MA: Blackwell, 1993); Stewart Goetz and Charles Taliaferro, Naturalism (Grand Rapids, MI: Eerdmans, 2008);
 For difficulties with this picture see Bas van Fraassen, “ “.
 Daniel Stoljar, “Physicalism,” Stanford Encyclopedia of Philosophy,
 John Heil, The Nature of True Minds (Cambridge: Cambridge University Press, 1992), 5.
 For a further discussion of supervenience see Heil, The Nature of True Minds, chapter 3. Many philosophers have worried that this picture results in the consequence that consciousness is causally inert. In other words, the mind does not do things in the world. See Heil, The Nature of True Minds, chapter 4; cf. David Chalmers, The Conscious Mind: In Search of a Fundamental Theory (Oxford: Oxford University Press, 1996), 150-60.
 E.O. Wilson, Consilience: The Unity of Knowledge (New York: Vintage, 1999), 263.
 Dembski, “Naturalism and Design,” in William Lane Craig and J.P. Moreland, eds., Naturalism: A Critical Analysis (London: Routledge, 2000), 253.
 Bielfeldt, “The Peril and Promise of Supervenience,” in Niels Henrik Gregersen, et. al, eds. The Human Person in Science and Theology (Edinburgh: T&T Clark, 2000), 140-7.
 First, his model seems to make God dependent on the existence of the universe. Second, unless Bielfeldt can secure a top-down casual influence from the supervenient entity to the subvenient base, God’s action in the world will be rendered inert.
 John Durham Peters writes: “Joseph Smith wrote that spirit was a form of matter, and that God the Father and his Son have tangible bodies of flesh and bone” (D&C, 130, 131).” “Reflections on Mormon Materialism,” Sunstone, 16, no. 4 (March, 1993), 47.
 A.H. Armstrong writes, “In spite of his ferocious contempt for the philosophers and for all professed and conscious attempts to adapt Christianity to pagan philosophy he was himself very deeply affected by Stoic thought, and like the Stoics is unable to conceive of any kind of real substantial being which is not body; therefore as God and the soul are undoubtedly real and substantial they must, for Tertullian, be bodies.” An Introduction to Ancient Philosophy (Totowa, NJ: Helix, 1981), 168.
 We will encounter him again later in the chapter when we discuss antitheism.
 Nagel, Mind and Cosmos (Oxford: Oxford University Press, 2012), http://plato.stanford.edu/entries/physicalism/ (Accessed June 25, 2016).
 “I do not find theism any more credible than materialism as a comprehensive world view. My interest is in the territory between them.” Nagel, Mind and Cosmos, 22.
 Nagel, Mind and Cosmos, 57.
 Nagel, Mind and Cosmos, 32.
 Nagel, Mind and Cosmos, x. Also see Joseph Brean, “‘What has gotten into Thomas Nagel?’: Leading atheist branded a ‘heretic’ for daring to question Darwinism,” in National Post (March 23, 2013), http://news.nationalpost.com/holy-post/what-has-gotten-into-thomas-nagel-leading-atheist-branded-a-heretic-for-daring-to-question-darwinism (Accessed July 1, 2016).