Monday, January 01, 2018

Spinoza's Neurobiology: The Emergence of the Mind in the Body and the Brain

The human mind is the idea of the human body.

This assertion by Spinoza in his Ethics (particularly, part 2) can be judged as a claim about human biology open to confirmation or falsification by recent research in neurobiology.  If this is so, then this illustrates a point that I have often argued on this blog--that the history of political philosophy is largely a history of debatable empirical claims about human nature, social life, and the natural world generally that can be interpreted and assessed in the light of modern scientific knowledge.

Some folks might object that Spinoza is speaking as a philosopher, who appeals to logic and intuitive judgment, rather than as a biological scientist, who relies on hypothesis-testing through empirical research.  But this modern distinction between philosophy and science was not accepted in Spinoza's time, when what we today would call "natural science" was called "natural philosophy."  Beginning in ancient Greece, philosophers like Aristotle engaged in biological research.

Moreover, Spinoza indicated that his understanding of the relationship between the mind (mens in Latin) and the body (corpus) depended on his understanding of the brain (cerebrum).  Our thoughts arise in our brains as stimulated by the motions that our bodily nerves receive from objects outside of us and from the internal activities of our bodies (Ethics I, appendix).  Spinoza took seriously Descartes's research on human anatomy and physiology; and although he rejected Descartes's claim that the pineal gland is the place in the brain where mind and body meet, and although he saw this as contradicting Descartes' assumption that that mind and body are two distinct substances, he assumed that thought must arise somehow and somewhere in the brain (V, pref.).  Spinoza thus left open the possibility that increasing knowledge of the brain might reveal how mind emerges in the brain from its integration of signals from the body, which would explain the neural basis for what he saw as the parallelism of mind and body.

Indeed, Antonio Damasio has argued, in Looking for Spinoza, Spinoza's intuition that the mind is the activity of the body is confirmed by modern neurobiological evidence that "mental processes are grounded in the brain's mappings of the body, collections of neural patterns that portray responses to events that cause emotions and feelings" (12).

This Spinozistic claim that our conscious feelings arise from neural mappings of body states can now be experimentally tested.  For example, Damasio and his colleagues have hypothesized that when feelings occur, there is increased neural activity in those areas of the brain that receive signals from the body and thus map the ongoing state of the body.  These brain areas are at different levels of the central nervous system, which include several nuclei in the brain stem tegmentum (the back part of the brain stem), the hypothalamus, two of the somatosensory cortices (the insula and the secondary somatosensory cortex), and the cingulate cortex.

To test this hypothesis, Damasio and his colleagues recruited forty people with no history of neurological or psychiatric disease.  The subjects were asked to think of some intense emotional episode from their lives that involved happiness, sadness, fear, or anger.  They were in a brain scanning room so that machines could measure blood flow in their brains using the technique of PET (positron-emission tomography), with the understanding that increased blood flow to some region of the brain is correlated with the local activity of the neurons.  The subjects were asked to signal with a hand movement the moment they began feeling the emotion--happiness, sadness, fear, or anger.  The brain scans showed increased activity in the predicted areas of the brain, which indicated that the mapping of body states had been modified during the process of conscious feeling.

Apparently, what was happening is that in the past, body states had induced a feeling like anger in the brain, and then this experience had been stored in memory; so that when they recalled this memory of anger to recreate the feeling of anger, they activated the neural circuitry of the body-sensing brain regions associated with this feeling.

Here, then, Damasio concludes, we can see in these brain images the correlation of mind and body claimed by Spinoza.

Damasio's use of brain imaging to support this kind of argument is illustrated in this TED talk:

There are, however, at least three problems with Damasio's use of neurobiology to support Spinoza: the mystery of subjectivity, the self-refuting character of materialist science, and the experience of spirituality.

In his TED talk, Damasio passes over the mystery of subjectivity in two sentences about two minutes into the talk.  He says that many people, including many neuroscientists, have said that human self-consciousness is too mysterious to be explained scientifically.  He rejects this.  But then he says: "It would be ridiculous to claim that we know how we make consciousness in our brains. But we can begin to approach the question and to see the shape of an answer."  Here he is pointing to what he calls the "consciousness puzzle" in Looking for Spinoza (198).  We can see neural patterns through the "tools of neuroanatomy."  And through the "tools of introspection," we can subjectively see our own mental images or ask other people to report their mental images to us.  But we cannot see the process by which observable neuroanatomy creates subjective introspection.  We see correlation but not causation.

In his experiment with the 40 people asked to create feelings of happiness, sadness, fear, and anger, he could see the PET brain images, but he could not see their conscious feelings, because he had to rely on the people to report to him what they were feeling.

In his book, Damasio admits that there is a "knowledge gap" here (208).  He observes:
"The mind level of biological phenomena has additional specifications that are not present at the neural-map level.  I hope a reductionist research strategy eventually will allow us to explain how we get from the 'neural-map' level to the 'mental' level, although the mental level will not 'reduce to' the neural-map level because it possesses emergent properties created from the neural-map level.  There is nothing magic about those emergent properties, but there is a lot that remains mysterious, given our massive ignorance of what they may involve" (325).
As I have indicated in my posts on the evolutionary emergence of the mind in the brain, I agree that there is nothing magic here, but I also agree that there is some mystery as long as we cannot explain exactly the natural process by which the observable brain causes the subjective mind.

The biblical creationist might say that the only way to resolve this mystery of consciousness is to see that the conscious human mind is the creation of God in His image.  But as I have indicated in another post (here), this falls into the fallacy of explaining a mystery through an even greater mystery.

The second problem for Damasio's Spinozist neurobiology is the possibility that any materialist science that sees the human mind as the product of mindless evolution becomes self-refuting.  (I have written about this here.)  Damasio never recognizes this problem.

One of the best arguments for theism is that the theistic doctrine of the human mind as created by God in His image provides the necessary support for believing in the validity of human thought, including the validity of modern science. If we embrace Naturalism--the view that nothing exists except Nature, and so there is no transcendent Creator God--we are caught in self-contradiction: if human thought originated not from a divine Mind but from the irrational causes of Nature, then we cannot trust our minds as reliable, and thus we cannot trust our belief in Naturalism. Naturalism destroys itself by destroying the rationality of believing in Naturalism, or anything else. Insofar as science--including evolutionary biological science--depends on the validity of human thought, and insofar as theism is the indispensable support for trusting in the validity of human thought, science is not only compatible with theism, science depends upon theism.

Natural selection rewards adaptive behavior and punishes maladaptive behavior. But natural selection does not care about the truth or falsity of an animal's beliefs. If beliefs produce adaptive behavior, they will be rewarded by natural selection regardless of whether the beliefs are true or false. Therefore, the evolution of adaptive behavior in our prehistoric ancestors did not guarantee or make it probable that our cognitive faculties would be reliable in generating mostly true beliefs.  Even Damasio admits that as produced by evolution, the brain is not a passive mirror of objective reality, because it constructs its own images of the world to serve the evolved purposes of survival and reproduction (199-209).

The weak link in this reasoning, however, is the assumption that adaptive behavior is completely unrelated to true belief. On the contrary, the evidence of evolutionary history suggests that evolution produces cognitive faculties that are reliable but fallible. The mental abilities of animals, including human beings, are fallible because evolution produces adaptations that are good enough for survival and reproduction but not perfect, and this results in the mental fallibility that is familiar to us.

Despite this fallibility, the mental faculties cannot be absolutely unreliable. In the evolution of animals,adaptive behavior requires accurate indicators. So, for example, a frog must have sensory equipment that allows him to accurately detect flies so that he can catch them with his tongue.  The waggle dance of bees must convey accurate information to other bees. Similarly, the immune system of the human body must accurately indicate the presence of foreign bodies and then accurately devise responses to destroy the invaders.

For those animals who develop some capacity for conscious reasoning--and most preeminently human beings--the accuracy of this conscious reasoning will be important for adaptation. The highest mental capacities of human beings are so biologically expensive in terms of the investment of energy they consume that it is implausible that evolution would have produced them unless they improved the ability of human beings to track the truth about themselves and their environment. Again, this is going to be fallible, but it's implausible that human beings could be naturally evolved for being in a state of complete and perpetual delusion.  These reliable but fallible cognitive capacities can then be appropriated for scientific research, which must include methods to minimize those evolved biases that impede our accurate perception of the world, an important theme for Spinoza.

The third problem for Damasio's Spinozist neurobiology is whether it can account for and satisfy the human need for spirituality and religious salvation.  Damasio does recognize this problem (267-89).

If Spinoza is right about the essence of human nature being the natural striving for self-preservation, then we might expect that when we confront the reality of suffering and death, we naturally strive to escape that vulnerability and mortality in achieving some enduring if not eternal joy in our lives and the lives of those we love.  Our striving for self-preservation becomes a striving for salvation.

Spinoza identifies two ways to human salvation--one for the many common people (the vulgus), and the other for the philosophic few.  For the common people, salvation can come only through faith in biblical revelation:
". . . I judge the utility, even necessity, of Sacred Scripture, or revelation, to be very great.  We can't perceive by the natural light that simple obedience is a path to salvation.  Only revelation teaches that this happens, by a special grace of God, which we cannot grasp by reason.  It follows that Scripture has brought great comfort to mortals.  Everyone, without exception, can obey.  But only a few (compared with the whole human race) acquire a habit of virtue from the guidance of reason alone.  So, if we didn't have this testimony of Scripture, we would doubt nearly everyone's salvation" (TPT xv.44).
For this reason, Spinoza did not want common people to read his books, because this would do them no good (TTP, pref. 34).  He wrote his books in Latin and discouraged any translations into Dutch, because he wanted to be read only by those few learned people who could read Latin.

The philosophic few could not take the first way to salvation, because they accepted the truth of human mortality, and thus they could not believe in salvation through resurrection to eternal life with God.

For the philosophic few, there was a second way to salvation--what Spinoza at the end of The Ethics called  "the mind's intellectual love of God," which induces that fullest satisfaction of the mind that is felt as Joy, and which is eternal (V, prop. 34-42).  When I first read The Ethics in Cropsey's class, I struggled to understand what this means.  I still do.

If atheism is the denial of the existence of God or of anything divine, then Spinoza was not an atheist, because he does affirm the existence of God (Ethics I, p. 11). Spinoza denied the common charge that he was an atheist.

But if atheism is denial of the existence of a personal God, who cares for human beings, who listens to prayers, who reveals Himself miraculously to human beings, who demands obedience to His law, and who rewards and punishes human beings in an eternal afterlife, then Spinoza was an atheist.

One can say for sure that Spinoza's God is an absolutely infinite being that is the first cause--the uncaused cause--of all things, that it is a being that human beings can love, and that this love of God is the greatest human good, although in loving God, human beings cannot expect God to love them in return.

Spinoza's phrase "God or Nature" (Deus sive Natura) has led some people to say that Spinoza is a pantheist who identifies the whole universe as divine (IV, pref., p. 4).  But then Spinoza says that God as first cause is to be identified with "nature naturing" (Natura naturans) rather than "nature natured" (Natura naturata) (I, p. 29).  And yet he also says that he does not separate God from nature as other philosophers do (letter 6).  (Is "Nature's God" in the Declaration of Independence Spinoza's God?  I have written about this here.)

Spinoza seems to be affirming a secular or naturalistic religiosity based on a religious feeling of awe, love, or joy in contemplating the order of nature, but without any sense of a personal God.  As Damasio indicates, this was most powerfully affirmed by Albert Einstein, who said that his God was Spinoza's God.  He described the religious feeling of the "profounder sort of scientific minds" as taking "the form of a rapturous amazement at the harmony of natural law, which reveals an intelligence of such superiority that, compared with it, all the systematic thinking and acting of human beings is an utterly insignificant reflection."  He described this feeling as "a sort of intoxicated joy and amazement at the beauty and grandeur of this world, of which man can form just a faint notion.  This joy is the feeling from which true scientific research draws its spiritual sustenance, but which also seems to find expression in the song of birds."  This might be what Spinoza meant by amor intellectualis Dei.

And what can a neurobiologist like Damasio say about this?  At the very least, he observes, "the spiritual is a particular kind of feeling state. . . . a particular state of the organism, a delicate combination of certain body configurations and certain mental configurations" (286).

But if Spinoza is right, these religious feelings in the brain do not point to any transcendent reality beyond nature.

In my copy of the Elwes translation of Spinoza's Ethics that was the text for Cropsey's class, I wrote this note in the margin of the text for Part 5, proposition 30: "On the intellectual love of God, compare Lucretius: 'it is true piety to be able to contemplate all things with a calm mind' (5.1205)."

Is that enough for our salvation--at least for those few like Einstein who can feel joy in contemplating the beautiful order of a natural world that is joyful in being intelligible to our minds, although it does not care for or about us, so that we can love it without expecting to be loved in return?

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