"I think, therefore I have a soul" - Alvin Plantinga on the Soul

“Consciousness” writes J. P. Moreland, “is among the most mystifying features of the cosmos” (“The Argument from Consciousness” 119). Consciousness mystifies us because it is at once incomprehensible and deeply familiar. I identify with it and live within it, but if you ask me to define it, I cannot. The apparent identity of myself and consciousness gives questions of the mind a level of significance that is hard to beat. If I am nothing other than my brain, then when my body dies, so do I. If I am something more, then perhaps I continue even when my body ends.

My focus is on an argument from philosopher Alvin Plantinga for the soul’s existence. His claim is that material things cannot think, and because I clearly can think, I am not a material thing. After examining the argument on its own terms and then in the light of recent neuroscientific evidence, I conclude two things: (i) that Plantinga does not succeed in giving sufficient evidence for the soul, but also (ii) that modern science does not rule out a soul.

I. Overview of the field

Plantinga’s argument is a practice in the philosophy of mind, a field that begins with the basic distinction between mental and physical. Leaving physical to be defined intuitively, mental things encompass “beliefs, desires, intentions, emotions, itches, tickles, pains, sensations, perceptions, intuitions, thoughts…and so on” (Oppy 136–137).

Take beliefs as a jumping-off point: beliefs are those things we have when we entertain a statement and take an attitude towards it (Moreland, The Soul 27–28); we affirm, doubt, trust in, or reject them. Moreover, beliefs have intentionality. For example, I believe that Calculus is an unnecessary hoop to make high school students jump through. Here, my belief is about mathematics. One might say that math is the content of my belief. This property of “being about something else” or “having content” is known as intentionality, and it serves as a hallmark of consciousness.

Understanding the relationship between the mental and the physical is known as the mind-body problem. Here the philosopher attempts to craft a plausible theory of how the mind relates to the body, how the soul (if it exists) interacts with the brain, and so forth. There are two classes of solutions to the problem: monism and dualism.

According to monism, a person is composed of one type of thing: either immaterial mind alone (idealism) or physical material alone (physicalism). The former generally holds that the entire physical world is an illusion, while the latter holds to some identity between the mind and the brain.

Dualism, however, contends that a person is a composite of both mental and physical realities. The main form of dualism that concerns us is substance dualism, a view that contends that a person is a combination of two substances: a body and a soul. It is the thesis “that the mind and its contents are…neither themselves physical, nor the logical byproduct of anything physical” (Foster 455). In general, the soul is conscious; the brain is not. Plantinga’s argument, then, is an argument for substance dualism.

Descartes claimed that “the whole essence or nature of” a human person is “simply to think” (19). Alvin Plantinga, perhaps inspired by this claim, develops an argument for the soul based on our ability to think (11–22). His thesis is that physical things — quarks, electrons, waves, fields, and forces — cannot produce thought. Insofar as people can think, it follows that people are not physical things. They are therefore immaterial things, a soul or mind.

1. I am a thinking thing.
2. Physical things cannot think.
3. Therefore, I am not a physical thing.

II. The argument on its own terms

Plantinga simply presupposes premise (1), but it is clear enough that I am a thinking thing. Indeed, to argue that we do not have thoughts or beliefs seems pointless. For if we literally have no thoughts, it is unclear why one would bother trying to get people to think that there are no thoughts or to believe that there are no beliefs.

Some philosophers suggest that the intentionality or content of our thoughts is an illusion. It may seem, for instance, that I am thinking about the National Football League, but in fact, I am not. However, this proposal is self-refuting because illusions have intentionality; illusions are about or of certain things (Craig “The Mind”). Premise (1), then, is secure.

Plantinga outlines two reasons to think that a physical thing like the brain cannot believe statements or think about things — premise (2).

I. The first argument is that if it is the physical brain that thinks, an underlying physical process would have to generate thought, a feat Plantinga thinks is impossible. He asks us to imagine one solitary quark, floating around in space. Clearly, this quark is not capable of thought — reasoning, believing, and entertaining certain statements. Now imagine two quarks. Can this ensemble think? Clearly not. We can continue our thought-experiment and imagine an arbitrarily large number of quarks, banging around and combining to form more and more complex structures, and yet “we won’t find anything composed of them that can think” (Plantinga 13), including the brain itself.

I have two problems with this argument. First, it presupposes that a capacity for thought is not an emergent property. An emergent property is a property that a collection as a whole possesses, while the members of that collection do not. For example, individual molecules of hydrogen and oxygen do not have the property of wetness. Nevertheless, as we “zoom out” to see the whole structure, wetness emerges as a property of water. Plantinga fails to consider the possibility that consciousness is emergent; even if each quark is not capable of thinking, perhaps thought emerges on a higher level of structure. By overlooking this option, Plantinga commits the fallacy of composition when he argues that because every individual quark lacks capacity x, therefore the collection of quarks (i.e., the brain) lacks x.

Second, the argument commits the fallacy of ambiguity used in sorites paradoxes. One version of these begins by asking us to consider how many grains of sand must come together before one has a heap. We know that one grain will not do the trick. By the same thinking, two grains will surely not do; but then, neither will three. In this way, we seem forced to conclude that “no amount of [sand] can make a heap” (Hyde). However, we know that heaps exist. Therefore, our thought experiment must have gone wrong somewhere. On the surface, Plantinga appears to be arguing in a similar way.

Sorites’ Paradox

1. One grain does not make a heap.
2. If one grain does not make a heap, neither does two.
3. If two does not, neither does three.

…

If 99,999 grains do not make a heap, neither do 100,000.

Conclusion: 100,000 grains do not make a heap.

Plantinga’s Argument

1. One quark cannot think.
2. If one quark cannot think, neither can two.
3. If two cannot, neither can three.

…

If ten trillion quarks cannot think, neither can a brain.

Conclusion: A brain cannot think.

Take the sorites’ argument: it is logically valid, the premises seem to be true, and yet, the conclusion is false — hence the paradox. Insofar as Plantinga argues in the same form, one can have no confidence that his conclusion is true, even if his premises seem true and his logic sound.

In response to this objection, Plantinga may argue that the sorites’ reasoning is not parallel to his own. He may point out that the paradox occurs because of the vague definition of heap — as soon we define the term (e.g., a heap is composed of seven-hundred grains of sand), the paradox disappears. Per Plantinga, he does not use similarly vague terms and therefore his argument is sound, even if the sorties’ is not.

On the contrary, Plantinga’s argument only works because thought is an ambiguous concept. For example, let us say that to think about a statement x is to mentally entertain x. What do we mean when we say one entertains something? The second word is no clearer than the first. Or again, if we claim that to believe a claim x is to take a stance towards x, “taking a stance” can only be a metaphor, for the mind has no legs to stand on — but a metaphor of what? I do not know. In short, both arguments exploit the lack of concrete analysis of key terms — heap and thought, respectively — and therefore fail to support their respective conclusions.

In conclusion, Plantinga’s first argument for premise (2) fails.

II. Plantinga’s second argument for premise (2) is based on the observation that thoughts have content; they are intrinsically about something else. This is the property of intentionality mentioned earlier. For instance, I believe that researching the mind-body problem is interesting at times and dreadful at others. Here, my belief is about the philosophy of mind (and the latter is the content of the former). Or again, I realize that I have not yet unloaded the dishwasher; I am thinking of the household appliance.

The rub is that it is extremely difficult to see how a physical structure like a group of neurons can be about something else. For example, if I am joyously recalling the Broncos’ Super bowl 50 win, what does it mean to say that this hunk of my brain is about the Denver football team? If I am contemplating the ever-increasing complexity of Apple iPhones (call this belief p), what determines the relationship between the group of neurons supposedly identical with p and an iPhone? If we take out a piece of paper and record the number of neurons within p, the number of synapses, the rate of fire, and the electrical activity therein, we will have no inkling whatsoever that p is about iPhones. Indeed, “none of this seems even relevant” (Plantinga 13) to determine the content of p. Therefore, it is plausible that physical things are about nothing — they just are — including the brain.

In short, Plantinga claims that when we carefully reflect upon physical things, we can in some sense ‘just see’ that they never could have intentionality. Boiled down to its essentials, we are presented with two statements about any object x:

1. x has content.
2. x is physical.

Point (1) is the claim that x is about something else. Point (2) is the claim that x belongs to the realm that Physics as a discipline studies. Plantinga maintains that (1) and (2) are broadly logically incompatible; if one of them is true, the other is false.

I grant that we do have an ‘awkward’ sense when we contemplate a hunk of neurons supposedly identical to thoughts — let us call these hypothetical entities neuron-thoughts. Nevertheless, we need more than a vague discomfort to have a successful argument for substance dualism. While some are content to just assert that neuron-thoughts are impossible (Craig and Moreland 237), this assertion rings hollow if one cannot explain what the problem is.

Plantinga’s discussion is convoluted, and I will tease out all interpretations I can so that I might connect with his intended meaning. I distill three ways he claims to help readers see the incompatibility of the two points outlined above: (i) it is mysterious how a neuron-thought could gain its content — “How can that happen?”, (ii) we cannot find the content of a thought by looking into the brain — “nowhere, here, will we find even a hint of content”, and (iii) the very statement that neuron-thoughts are about something is nonsensical — “what is it for such an event to have a content?” (Plantinga 14).

With respect to (i), the claim is that we cannot explain how neuron-thoughts manage to carry out the incredible feat of having content, being about something else. To unpack this claim, observe that one can have a thought about almost anything (Moreland, “The Soul and Life Everlasting” 433). For example, I am now thinking about Pluto’s orbital path. If thoughts are nothing more than brain states, just how is it that this one physical structure comes to be about Pluto? If I begin to contemplate the United States Congress, what force acts to relate Congress to a hunk of my brain? No answer is forthcoming.

However, Plantinga’s inability to articulate how the brain gains its content is no reason to conclude that neuron-thoughts are impossible. The physicalist can claim that it just is the nature of particular neuron structures to be about their respective objects. Perhaps some structure simply must be about Congress; if I were thinking about apples, I would have a different thought in my mind and therefore a different structure in my brain. Asking why a particular arrangement of neurons is about Congress is like asking why 2 + 2 = 4. It simply must be that way. There is a mystery here, but it is the broader mystery of something having an essential nature.

Plantinga will respond that physical things, unlike mathematical truths, do things by way of physical mechanisms. My car moves forward because its engine, tires, and axles come together in the right way. Similarly, if the brain thinks, it must do so by way of the interactions of its parts. Therefore, even if it isn’t appropriate to ask why 3 x 7 = 21, it is legitimate to ask how the brain comes to be about other things.

This is not a good counter-response. If Plantinga is merely reiterating his claim that an underlying physical process cannot lead to thought, we have seen that his argument fails to take seriously the proposal that consciousness is emergent. In such a case, questions of how are still off the mark. For example, how is it that wetness emerges as a property of water? It is entirely mysterious, and yet, it happens. Plantinga has given no reason to think that intentionality and content cannot be emergent, and therefore argument (i) fails.

Regarding (ii), we look to the brain, we peer into it and dissect it, we see the electrical pulses, the neurons and synaptic connections; we measure the rate of fire, even the potential voltage — nevertheless, we still must ask: where is content? In the abstract structure? In the spatial relationships between neurons? In the electrical activity? In the atoms themselves? None of these things seem even remotely related to the economy, Congress, the dishwasher, or whatever else I might be thinking of. In short, Plantinga seems to argue that from our inability to see the content of thoughts in the brain, it follows that nothing is there for us to see.

This argument is invalid. Plantinga asserts the following:

1. We cannot find the content of thoughts by looking into the brain.

He then infers that neurons cannot constitute thoughts. This inference, however, is invalid unless we add an additional premise: (2) If thoughts reside in the brain, we should be able to find their content.

One cannot argue from claims about knowledge to claims about existence unless something like (2) holds. However, Plantinga gives no reason to think that (2) is true. I see no reason to think that if thoughts manifest themselves in physical structures within the brain, then we would be able to discern their content. Therefore, (ii) remains an argument from ignorance.

Finally, (iii) is the claim that neuron-thoughts are nonsensical. One might as well suggest that a group of rocks lying on the ground is about the Irish potato famine — the sentence itself seems malformed, like the assertion that philosophy weighs seven-hundred pounds. On the surface, then, neurons cannot constitute thoughts because the very assertion that they can has no clear meaning.

In response, it does not follow that because one physical thing — rocks — cannot have x, therefore the brain cannot have x. If thought and consciousness are emergent realities — non-existent on the fundamental level of atomic interactions, but prevalent at a higher level of structure — we can understand why ascribing intentionality to rocks is unintelligible: they do not have enough complex structure to generate thought. The same cannot be said about the brain, with over one hundred billion neurons and one thousand trillion synaptic connections. Indeed, I cannot mentally grasp this order of magnitude, so I find it unlikely that we are even capable of reflecting on what properties the brain could or could not have, including intentionality.

In short, I find myself without the awareness that neurons and gray matter cannot possess intentionality, and I cannot find a route to make that intuition any clearer. Perhaps there is an argument for dualism here, but I cannot find it.

In conclusion, while premise (1) is probably true, Plantinga fails to give any good reason to think that premise (2) is true. Therefore, his argument does not furnish good grounds to conclude that an immaterial soul exists.

III. Does neuroscience undermine belief in the soul?

Continuing upon our discussion above where I argued that premise (2) was unsupported, we now turn to neuroscientific evidence that ostensibly suggests that (2) is demonstrably false. Scientific American reports that in some circumstances, scientists can peer into the brain and find out whom someone is thinking of (Choi), basing this claim off a study published in Cerebral Cortex (Hassabis et al.). In that study, a team of scientists developed eight fictitious characters — Mike, Chris, Dave, Nick, Ashley, Sarah, Nicole, and Jenny. Each character differed in their levels of extraversion and agreeableness (Nick feels anxiety when in large groups, Ashley talks to everyone at a party, etc.), thereby corresponding to eight distinct personality types. Nineteen people underwent a brain scan, wherein scientists asked them to imagine four of these characters in various circumstances — in a bar, in the park, and so forth — and predict how they might behave given what they knew about their characters’ personalities.

By analyzing images of the brain during these scans, scientists discovered a tight correlation between mental states like imagining Chris swimming in the pool and increased blood flow in a specific region of the brain. Generalizing the results, the team developed a general model that allowed them to determine what type of person someone was thinking about, merely by observing their brain activity.

The question now arises: if a scientist can crack open my skull and discover whom I am thinking of, does this imply that my thoughts reside within the brain, rather than in an immaterial mind?

Perhaps not. It is incorrect to suggest that the research team asked people to think of anyone in the world, and then amazed them by correctly guessing whom they were imagining.[1] Rather, the only reason researchers could read brain activity and determine one’s mental state was that they knew beforehand the model or key for interpreting brain activity:

• Mental state x corresponds to brain state x’
• Mental state y corresponds to brain state y’
• Mental state z corresponds to brain state z’

They discovered this key by a three-step process. First, they told participants whom to imagine. Second, they collected data from all nineteen people. Third, they synthesized that data and derived connections between brain states and mental images. The important point here is step one: without that earlier agreed upon mental state, no scientist in the world could have determined whom participants were visualizing. The experiment does not prove that thoughts reside in the brain because knowledge of the brain state alone would not inform an observer whom someone was thinking of, even if it does point to important correlations between mental states and brain states.

Correlation, after all, is not the same thing as identity (Goetz 267). For example, every time I stub my toe, there is an increase in activity in some region of my brain, and yet my brain is not identical to the act of toe injury. By the same token, every time I think about a person, there is corresponding blood flow in my brain; we cannot infer from this, however, that the two are identical. In short, it is consistent with neuroscience to hold that thoughts are states of the soul, and that these states are always conjoined with particular brain states.

The physicalist may ask how it is that the mind and body can be so connected to correlate consistently with one another, and yet still qualify as separate things. Indeed, many claim that substance dualists ought to be surprised by the fact that so much of our mental life stems from a functioning brain — damage the brain, and one damages the mind (Corcoran 274). Alzheimer’s disease, traumatic brain injury, and even syphilis illustrates the point. If consciousness stems from the soul, “one would expect…[it] to be relatively invulnerable to…damage to the brain” (Churchland 453). Because it is susceptible in this way, consciousness is better taken as stemming from the brain.

It seems to me, however, that the dualist may plausibly point out that insofar as one is a dualistic interactionist, he believes that the soul uses the brain as an instrument of thought, much like the guitarist uses the guitar as an instrument to make music (Craig, “Questions”). When one damages the guitar, one damages the music; when the brain is damaged, so is consciousness. However, these facts no more call into question the soul’s existence than they do the existence of the guitarist.

In short, neuroscience gives little reason to conclude that premise (2) of Plantinga’s argument is false or that the soul does not exist.

IV. Conclusion

In conclusion, Plantinga’s claim that physical things cannot think does not support the idea that an immaterial soul exists. However, neuroscience does not make that idea implausible, either. Personally, I have come to a place of agnosticism: it seems to me that we have little reason to think that premise (2) is true, but also no reason to think that it is false (per my investigation into neuroscience). The bewildering complexity of the human brain leads me to conclude that the only intellectually honest answer is that we simply do not know whether the brain could give rise to consciousness. This was not my original assessment, having initially concluded that Plantinga’s argument was sound. I now think differently.

This agnostic conclusion might prove dissatisfying to some, but it seems to me that the current state of unknowing is not the end destination: perhaps it is merely a rest stop along the road to greater knowledge. The philosophical quest, after all, is a lifelong endeavor, and even then it does not stop but stretches on from person to person, generation to generation, and century to century. The conversation is always alive, never-ending. The joy is to give one’s own thoughts and perspective, for no one can see the world exactly the way you do. And perhaps, if a thousand perspectives come together and a thousand voices speak in tandem, we may see the world as it truly is.

Notes

[1] To see this, realize that researchers asked people to imagine three scenes: (i) devoid of people or activity, (ii) with themselves as the main actor, and finally (iii) with the relevant character. Scientists then used images of the brain associated with (i) and (ii) and compared them with (iii) to isolate the brain patterns corresponding with imagined people. This procedure serves as confirmation that it is only by knowing in advance what these brain patterns signify that researchers could later use them to infer mental states like imagining Mike playing tennis.

Works Cited

Choi, Charles Q. “Brain Researchers Can Detect Who We Are Thinking About.” Scientific American. Scientific American, 14 Mar. 2013. Web. 05 Aug. 2016. <http://www.scientificamerican.com/article/brain-researchers-can-detect-who-we-are-thinking-about/>.

Churchland, Paul. “A Refutation of Dualism.” Philosophy of Religion: Reader and Guide, edited by 

William Lane Craig, Rutgers University Press, 2002, pp. 447–454.

Corcoran, Kevin. “Human Persons are Material Only.” Ed. J.P. Moreland, Chad Meister, and Khaldoun A. Sweis. Debating Christian Theism. New York: Oxford University Press, 2012. 270–282. Print.

Craig, William Lane. “The Mind behind the Universe.” Reasonable Faith. Reasonable Faith. 29 April 2013. Web. 11 July 2016.<http://www.reasonablefaith.org/The-Mind-behind-the-Universe>.

Ibid. “Questions about Body-Soul Interaction.” Reasonable Faith. Reasonable Faith. 21 June 2015. Web. 11 July 2016. <http://www.reasonablefaith.org/questions-about-body-soul-interaction>

Craig, William Lane, and J. P. Moreland. Philosophical Foundations for a Christian Worldview. Downers Grove: Intervarsity Press, 2003. Print.

Descartes, Rene. Discourse on the Method for Conducting One’s Reason Well and for Seeking Truth in the Sciences. Translated by Donald A. Cress, Hackett Publishing Company, 1998.

Foster, John. “A Defense of Dualism.” Philosophy of Religion: A Reader and Guide, Edited by William Lane Craig, Rutgers University Press, 2002, pp. 455–475.

Goetz, Stewart. “Human Persons are Material and Immaterial (Body and Soul).” Ed. J.P. Moreland, 

Chad Meister, and Khaldoun A. Sweis. Debating Christian Theism. New York: Oxford University Press, 2012. 261–269. Print.

Hassabis, D., R. N. Spreng, A. A. Rusu, C. A. Robbins, R. A. Mar, and D. L. Schacter. “Imagine All the People: How the Brain Creates and Uses Personality Models to Predict Behavior.” Cerebral Cortex 24.8 (2013): 1979–987. Oxford Journals [Oxford UP]. Web. 5 Aug. 2016.

Hyde, Dominic. “Sorites Paradox.” Stanford Encyclopedia of Philosophy. Stanford. 6 December 2011. Web. 28 June 2016. < http://plato.stanford.edu/entries/sorites-paradox/>.

Jaworski, William. Philosophy of Mind: A Comprehensive Introduction. Chichester: John Wiley and Sons, 2011. Print.

Moreland, J. P. The Soul: How We Know It’s Real and Why It Matters. Chicago: Moody Publishers, 2014. Print.

Ibid. “The Argument from Consciousness.” Ed. J. P. Moreland, Chad Meister, and Khaldoun A. Sweis. Debating Christian Theism. New York: Oxford University Press, 2012. 119–130. Print.

Ibid. “The Soul and Life Everlasting: Introduction.” Ed. William Lane Craig. Philosophy of Religion: A Reader and Guide. New Brunswick: Rutgers University Press, 2002. 429–446. Print.

Oppy, Graham. “Consciousness, Theism, and Naturalism.” Ed. J.P. Moreland, Chad Meister, and Khaldoun A. Sweis. Debating Christian Theism. New York: Oxford University Press, 2012. 131–144. Print.

Plantinga, Alvin. “Against Materialism.” Faith and Philosophy 23.1 (2006): 3–32. Philpapers. Web. 06 May 2016.