Christian Materialism in Philosophy of Mind: Combining the Worldviews of Freud and Lewis

Though science and faith have often been seen to conflict, especially in neuroscience and philosophy of mind, new work by Nancey Murphy and Warren Brown offers a new path of integration between these once-warring factions. Scientific thinkers, represented by Sigmund Freud, tend to favor reductionist physicalism – the mind can be reduced to the body, there is nothing more than the physical, whereas religious thinkers, such as C.S. Lewis, have often been tied with Cartesian dualism – the mind and the body are separate; there is something more, a soul, beyond the physical body. Murphy, a theologian and philosopher at Fuller Theological Seminary, proposes an alternative: nonreductionist physicalism, which rejects a metaphysically strong notion of the soul. After reviewing the concerns of C.S. Lewis against similar philosophies, I will show how Murphy’s model preserves the possibility for faith while meeting Sigmund Freud’s demands for a scientific worldview.

Before getting to the issue at hand, it is necessary to offer some more definitions. The “soul,” as it is usually understood, is a metaphysically strong notion; that is, there is some definite entity, albeit a non-physical one, which exerts some influence on the physical domain. The “mind” is simply the first-person experience of pain, joy, love, reason, etc. and it may or may not be physical. A reductionist is someone who says that mental states can be reduced to brain states; a mental state such as “love” can be explained by a description of the brain state as a certain configuration of neurons or neural activity. A physicalist is someone who says that the physical is all that exists; in the context of philosophy of mind, this is particularly applied to the brain or mind; physicalists believe that there are no supernatural entities involved in either. Physicalism within philosophy of mind need not commit one to the general view that only the physical exists; for example, Murphy still subscribes to the idea of a supernatural God while only believing in a natural mind.

There have been a couple of key cases that have pushed philosophers toward physicalism. Phineas Gage is a classic example from the 19th century. Gage was initially a hard-working and reliable young man, but he had a terrible accident while working on a railroad that damaged great portions of his brain. After this injury, Gage’s personality changed dramatically and he became easily-angered and irreverent. If there is a soul, philosophers ask, why would damage to the brain so greatly affect a person’s character? Furthermore, there has been a great deal of recent research into the mind and brains of animals. Chimpanzees have been capable of learning simple language and grammatical constructions, displaying cognitive abilities similar to infant human beings.1 If there is a soul, why do mental states have a gradient quality? Why do animals have mental states approaching the same type as human beings?

Of course, there are problems for the physicalist as well. One of the most notable questions is asked by C.S. Lewis in chapter three of Miracles – if knowledge “is merely a feeling in our own minds and not a genuine insight into realities beyond them – if it merely represents the way our mind happens to work – then we can have no knowledge.”2 If all mental states – including thoughts and ideas about the veracity of physicalism – are simply derived from configurations of the brain, then it seems arbitrary to say that one configuration is “true” and another configuration is “false.” So we arrive at a very serious problem in coming to understand the mind: on the one hand, we don’t want to construct an entity that doesn’t seem to have strong evidence for its existence and on the other, we don’t want to give up our reasoning abilities.

Fortunately, there is a solution: In Did My Neurons Make Me Do It? Nancey Murphy describes a nonreductive physicalist view of the mind. Though the physical brain is the only entity that exists, the configuration of its individual parts allows for explanatory structures that come from the brain as an entire system instead of from the atoms involved. That is, though neurons have particular properties that cause thoughts to emerge, those thoughts can be constrained by other factors. Murphy explains that the mind works “in terms of both bottom-up causes and constraints [so] a variety of behaviors is possible, and the important question is what constricts the possibilities to give the observed result.”3 She provides the analogy of an ant colony: ants possess both micro and macro behavior. Though each ant is endowed with a particular set of instructions to follow genetically, colonies also manifest particular behaviors (like aggressiveness and passiveness) that change with time. There is nothing in an individual ant’s set of genetic instructions that suggest this should occur; rather, when faced with particular environmental constraints, colonies tend toward a particular behavior due to the structure of their interactions. To compare this to the brain, though individual neurons may be genetically programmed a certain way, one must also look to environmental and structural factors to fully explain their behavior. When a complex net of neurons exists, it is subject to rules deriving from its structure that cannot be explained simply by describing the behavior of its component parts. Therefore, the system cannot be rightly described as “reductionist” because one still cannot reduce the brain to its component parts; a systematic view is also necessary. Murphy’s description of the mind appeals to the scientific worldview because it does not ascribe causal powers to supernatural entities like a “soul.” Though Murphy’s view meets the demands of science, we still have to see how it can deal with Lewis’ extensive criticisms in Miracles.

Lewis argues that because atoms are irrational, any beliefs caused by them must also be irrational.4 Whatever notion of the mind we develop, “we must believe in the validity of rational thought” or else we cannot insist on the truth of our claims about the mind.5 Lewis thinks that rational thought must come “by argument from observed facts.”6 If irrational objects become systematically arranged such that they form representations of observed facts, they would then be rationally determined. How could such an arrangement occur?

Murphy offers another analogy – a thermostat that regulates the temperature of a room. The thermometer attached to the thermostat simultaneously is affected by and affects the temperature of the room. In the brain, the mental state both affects and is affected by the environment. The thermostat and the brain are both self-regulating systems designed to match and affect the environment. We can define mental states as rational or irrational based on their correlation to environmental inputs or as Lewis calls it “observed facts.” So, for example, if the thermometer stopped responding to the correct temperature of the room and allowed the room to overheat, we would describe the thermostat as broken. Similarly, if the brain stops responding to environmental stimuli in an appropriate way – if it no longer describes observed facts – we can describe it as irrational.

Lewis is still concerned, however. It seems that we need someone to set the thermostat to the right temperature for the room; and the human brain needs to be set somehow to achieve rational thought. Yet if evolution is what sets rationality, then it seems we must defend the absurd conclusion that “because a thought is useful it must be (at least partly) true.”7 The problem is that this argument reverses the required conditional. As Lewis points out, to set the brain correctly to achieve rational thought, we need it to be the case that “if a thought is true, it is likely to be useful.” For example, it is universally agreed that “2+3=5” is a true statement. This is in part because it matches with our experience; we find that the representational numbers are correct when we work out the math by observing objects. Our brains would have to be sorely broken to observe reality and perceive a false statement that “2+3=6,” so broken, in fact, that it would be an obstacle to survival. This is all that is necessary for the evolutionary development of our brains to succeed in ensuring rational thought.

As we grasp these simple rational statements, our brain becomes capable of higher level rational thoughts. A few years ago, I was tutoring one of my younger cousins. She was still struggling with addition, and when going through flashcards, she would often incorrectly answer “4” or “6” to the equation “2+3.” It required much repetition to make her remember that “2+3=5.” Yet this repetition left imprints on the brain; with each repetition, recall is faster. A particular thought once engrained alters the neural network in such a way that the state is more likely to appear again. As the brain is trained to recognize rational statements like “2+3=5,” it can eventually advance to other rational statements like the principle of non-contradiction which are similarly affirmed by experience. Though the atoms composing the brain are irrational, their arrangement is determined by experiential inputs such that they yield rational beliefs.

Lewis offers one last worry for a physicalist view, saying “the naturalist will have to admit that thoughts, produced by lunacy or alcohol are just as valid as his own thoughts.”8 Yet in the example of the thermostat, it is clear that substituting the mercury for alcohol in the thermometer will affect the system in such a way that it no longer functions to best regulate the temperature of the room. The room could become unbearably hot or cold due to the disruption. In a similar way, when modified by chemicals or disease, the brain’s self-regulating rational system will go into error. The thermostat will be in error, and quite like the mind itself, will go wrong according to the amount of alcohol inserted. Just because the mental state is determined by the brain state does not mean that it is developed rationally in the same way that the room may be too hot or too cold even when its temperature has been determined by the thermostat.

To fully understand this, it is important to get a firmer grasp on what it means to be rational. It seems that there must be something more to rationality than simply making decisions based on observed facts. The individual ant in the colony observes the number of foraging ants near it and will alter its behavior based on this observation, but we do not want to consider an ant to be a rational entity. Murphy offers a better definition here:

“Mature human rationality develops when children attain the ability to consider why they are doing whatthey are doing, and then to raise the question of whether there might be better reasons for acting differently. . . children become independent moral reasoners when they can switch from acting to please parents or peers to acting on the basis of some abstract concept of good; not just what seems good to me now, but what is good per se. MacIntyre says: ‘In so evaluating my desires I stand back from them. I put some distance between them and myself qua practical reasoner.”9

The cognitive leap from ant to human being comes from the human’s ability to consider other options and then develop reasons for choosing one behavior over another. This choice is not determined by the individual atoms within the brain, but by the systematic reasoning function of the brain. This view helps explain why children, who do not yet have this system fully developed are not deemed completely “rational” (nor morally responsible). It is only when children have matured, when their neural nets are more established, that they can be deemed fully rational. Thus, Murphy’s view is more compatible with the other key problem in philosophy of mind: the appearance of gradient levels of cognition.

Of course, Murphy’s definition begs a question: where do agents get the idea of “good per se”? There is no a priori reason to think that the good should be advantageous, so the brain does not necessarily possess a self-regulating system for ethics. Furthermore, there are not observed facts about ethics; there are no purely physical or natural environmental stimuli that provides us with a clear direction for how we ought to live. Murphy’s view fits nicely with a Christian perspective, because it inherently implies that revelation is the only way to achieve certainty about morality. Of course, it is reasonable to think that God would direct the universe in such a way as to make some moral behavior evolutionarily advantageous (as appears to be the case with altruism). Yet the evolutionary intuitions alone would be insufficient to guarantee that a particular moral intuition was “reasonable.”

Murphy’s view is also helpful for the Christian because we can determine whether particular mental states involving religious commitments are rational given certain environmental conditions. So, for example, if one did observe one of Jesus Christ’s post-resurrection appearances, it would be fully rational to believe in Christ. It is only due to our distance from the event that provides epistemological uncertainty. In this case, there can be arguments about whether it is reasonable from a particular perspective to believe in Christ. Such a view comports with Freud’s demands for religion to be subsumed under science, without giving him a total concession to empiricism. In fact, we ought to test religious views to see if they match with reality; it is only through such testing that we can discern that some religions are irrational. Murphy’s view is perfect for the scientist or historian, who seeks to discern whether faith is reasonable, and for the Christian who holds his views on account of what has historically occurred.

Murphy’s view also allows for Freud’s idea of the person as influenced by environmental factors. Childhood impulses will have lasting effects on the overall person by affecting the development of the neural networks in the brain. Though this does not guarantee some of Freud’s more extreme theories like the Oedipus syndrome, it suggests that he was correct in attempting to analyze the impact of one’s childhood on their thoughts as an adult. Freud explains in The Question  of a Weltanshauung, that “the strength of Marxism clearly lies … in its sagacious indication of the decisive influence which the economic circumstances of men have upon their intellectual, ethical, and artistic attitudes.”10 Just as environmental factors contribute to reasoning ability, limited experience may give a person a bias in a particular direction. Thus, a poor person who had limited experience with poverty would not grasp arguments for lowering taxes on the upper income bracket as easily as one who had experienced wealth; while Marie Antoinette, on the basis of her limited experience, would declare in the face of starving Frenchmen, “let them eat cake!” Ultimately, Murphy’s view allows for a humble sense of human reason; it works, but imperfectly. In light of this fact, we may have to turn away from Freud’s desire for reason as a dictator,11 and turn to Pascal: “Be humble, impotent reason! Be silent, feeble nature! Learn that man infinitely transcends man, hear from your master your true condition, which is unknown to you.”12

So we see that Murphy’s view enables reason to have an influence while giving clear place for faith to enter in, which is ultimately what Lewis desires. It’s interesting to note that Lewis never explicitly defends dualism. Perhaps he was not as diametrically opposed to physicalism of the mind as is often supposed. In Miracles, he says “the distinction we have to make is not one between ‘mind’ and ‘matter,’ much less between ‘soul’ and ‘body’ (hard words, all four of them), but between Reason and Nature.”13 Lewis is surprisingly presentient in recognizing that we ought not get ourselves too concerned with the metaphysics behind souls and bodies. Hopefully, then, he would not be too distressed by a view like Murphy’s, which preserves reason while presenting a physicalist view of the mind.

There is one last criticism that Murphy’s view must encounter from the faithful Christian: why does the Bible speak of the soul if it doesn’t really exist? Fortunately, a full understanding of Murphy’s view quickly explains why Paul might speak of souls without committing himself to dualism. The history of intellectual thought shapes our understanding of terms, which is then impressed upon previous writers; Paul would not have necessarily held a Cartesian dualist view when he spoke of souls. To argue that his use of the term “soul” commits him to that metaphysical view is to commit anachronistic intellectual dishonesty. Rather, we can use linguistics and literary criticism – or even common sense – to understand that Paul’s use of “soul” ought not be understood as an ontological commitment to the soul. Murphy’s view is surprisingly compatible with scripture, in fact, for a physicalist view of the mind aligns perfectly with the traditional Christian view of bodily resurrection.

By using the observations of science, we can develop a better understanding of religious metaphysics that is compatible with both reason and faith. While so doing, we may use science to reach new insights on meanings previously overlooked. We may develop a greater appreciation for the Christian hope of bodily resurrection, taking more seriously our role as embodied beings and more accurately portraying the afterlife.14 We may understand to a greater extent what it means to be “a slave to sin.” Literally our neural networks are primed to commit sin, and we must diligently work to rewire them through changing environmental stimuli. As Lewis notes, we don’t need to understand the properties of poison to understand that we shouldn’t eat those “horrid red things.” Yet it is comforting to know that those horrid red things are still fully compatible with our modern understanding of the world and are not simply the machinations of an irrational mind.

The gulf between Lewis and Freud is not so insurmountable as might be thought, even in fields where scholars often stand in stark contrast to one another based on their religious views. Nancey Murphy’s view has demonstrated one particular way to cross the gulf between science and religion; hopefully her work can be continued in a number of other fields beyond the philosophy of mind. By combining elements from both worldviews, we may come to better grasp both the limitations of our reason and the essential role of faith to more deeply appreciate our nature as human beings.15


[1] Suddendorf, Thomas, and Andrew Whiten. 2001. “Mental evolution and development: Evidence for secondary representation in children, great apes, and other animals.” Psychological Bulletin 127 (5) (09): 629-50.

[2] Lewis, C. S. 1947. Miracles.” A preliminary study. London: G. Bles, the Centenary Press, p. 20

[3] Murphy, Nancey c., and Warren S. Brown. 2007. Did my neurons make me do it? .” Philosophical and neurobiological

perspectives on moral responsibility and free will. Oxford; New York: Oxford University Press, p. 95

[4] Lewis, C. S. 1947. Miracles.” A preliminary study. London: G. Bles, the Centenary Press, p. 22

[5] Ibid, p. 20

[6] Ibid.

[7] Ibid, p. 23

[8] Ibid, p. 22

[9] Murphy, Nancey c., and Warren S. Brown. 2007. Did my neurons make me do it? .” Philosophical and neurobiological

perspectives on moral responsibility and free will. Oxford; New York: Oxford University Press, p. 242

[10] Freud, Sigmund. “The Question of a Weltanschaunng.”, p. 178

[11] Ibid, p. 171

[12] Pascal, Blaise, and A. J. Krailsheimer. 1995. Pensees. Penguin classics. [pensees.J. Rev ed. London; New York: Penguin Books;

Penguin Books USA.

[13] Lewis, C. S. 1947. Miracles.” A preliminary study. London: G. Bles, the Centenary Press, p. 25

[14] For more on the theology behind this, see NT Wright’S Surprised by Hope.

[15] To read more about the conflicts and tensions between Lewis and Freud, I highly recommend Armand Nicholi’s A Question of

God. If you are a student at Harvard, I would also encourage you to consider taking his class of the same title. This essay was my

final paper for that class.


Jordan Monge ’12, the former Editor-in-Chief of The Ichthus, is a Philosophy and Religion concentrator in Quincy House.

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