Part 1: The heart in comparative physiology

Within natural theology, the heart and circulatory system has long been an icon of intelligent design. Not only does the heart so admirably show the craftsmanship of God, but William Harvey’s discovery of the circulatory system was considered exemplary of the usefulness of final causes and design arguments for the advancement of natural philosophy. Robert Boyle recounts in his Disquisition About the Final Causes of Natural Things (1688), that he once asked Harvey “What were the things that induc'd him to think of a circulation of the Blood?” Harvey’s reply could not have been more to Boyle’s liking:

He answer’d me, that when he took notice that the valves in the veins of so many several parts of the body, were so plac’d that they gave free passage to the blood towards the heart, but oppos’d the passage of the venal blood the contrary way : he was invited to imagine that so provident a cause as nature had not so plac’d so many valves without design: and no design seem’d more probable, than that, since the blood could not well, because of the interposing valves, be sent by the veins to the limbs; it should be sent through the arteries and return though the veins, whose valves did not oppose its course that way. (Boyle 1688, 157)

Natural theology, Boyle was trying to point out, is not a one-way street; not only can the new science help demonstrate the truth of Christianity, but in turn natural theology could also be a valuable heuristic to guide scientific inquiry. In fact, it would be mighty difficult to conduct physiological investigations without constantly asking what use or purpose any given structure has –a question which runs hand-in-hand with why a structure was designed the way it was.

To give another example; an important question at the time was whether humans were specifically designed to walk upright, and whether this made them special and above the brutes? In other words, are there design features unique to the human body, which demonstrate that God intended us to walk upright? To answer this question, the famous natural historian John Ray points out the remarkable design of the pericardial sack surrounding the heart. Our pericardium is special*, Ray tells us, because it helps support the diaphragm, preventing it from sagging too much – a design change deemed necessary for our upright position, as otherwise our organs would pull the diaphragm down preventing us from breathing properly:

Thus we see how necessary it is that in man the pericardium should be fasten’d to the diaphragm, and in quadrupeds how inconvenient it would be. And since we find this difference between the hearts of brutes and men in this particular, how can we imagine but that it must needs be the effect of wisdom and design, and that man was intended by nature to walk erect, and not upon all four, as quadrupeds do? (Ray 1743, 226)**

The heart, then, is considered exemplary of the distinction between man and beast. Another oft-repeated example of this special design of the human heart can be found in its connection to our brain. Firstly, it can be observed that in humans the heart is much nearer to the head than in brutes, a design change necessary for the copious amounts of blood that our brains require and the difficulty of pumping blood upwards. But more interestingly, we have a special nerve “sent from the cervical plexus to the heart, and praecordia. By which means the heart and brain of man have a mutual and very intimate correspondence and concern with each other, more than is in other creatures.”(Derham 1786, 20) This special correspondence between brain and heart shows, according to these men, that “the works of wisdom and virtue do very much depend upon this commerce which is between the heart and brain.” (Derham 1786, 21) Conversely, as the irrational creatures lack this special correspondence between brain and heart, we can find in brutes extra nerve connections from the vagus nerve to the heart – “so it is as remarkable an argument of the Creator’s art and care; who, although he hath denied brute-animals reason, and the nerves ministering thereto, yet hath another way supplied what is necessary to their life and state.” (Derham 1786, 22)

Part 2: The heart in philosophy of morals

Now to get to the contrapunctus, let’s take a look at Henry Home, Lord Kames’ Essays on the Principles of Morality and Natural Religion (1751). We come here upon a very different natural theological study of the heart, namely in its metaphorical moral meaning as the seat of our feelings or emotions. Lord Kames grounds our sense of morality not in some rationalist ethics or product of reason, but in deep inbuilt feelings or emotions of justice, duty, guilt, etc. “Lay [philosophical] prejudice aside,” he says, “and give fair play to the emotions of the heart.” (Kames 1976, 59)*** Indeed, he argues, what kind of design would it be, if our morals were based on such abstract reasoning, which only a minute fraction of the population has any capacity of understanding? How could God have expected us to be moral, if even the brightest minds cannot figure out what that means? What hope would there be for the rest of humanity? The mistake philosophers make is that they “endeavor to substitute reason in place of feeling. … overlooking the law written in his own heart.” (Kames 1976, 97) The armchair philosopher “vainly imagines that his metaphysical argument is just, because the consequence he draws from it happens to be true”. But this truth, Kames argues, is already “founded in our very nature”, by God’s design, and therefore the entire project of justifying it by rational arguments is completely in vain.

We come here upon a curious turn in which the study of morality is turned into a design argument itself****; only by studying God’s creation of the ‘human system’ can we come to a true understanding of morality. If God intended us to live in society, surely he would not have made us homo homini lupus, requiring some abstract chain of reasoning in order to behave morally. In the words of Frans de Waal; “[this] saying denies the inherently social nature of our own species.” (Waal et al. 2006, 3) No, rather than making us a wolf, God implanted in us the requisite moral frame.  In the words of Kames, “nothing can be more finely adjusted than the human heart to answer these purposes [of social behavior]” (Kames 1976, 67) and “There is perhaps not one scene to be met with in the natural or moral world, where more of design and of consummate wisdom are displayed, than in this under consideration.” (Kames 1976, 83)

And yet the philosopher ‘builds castles in the air’ and “flies to systems … according to his own taste and fancy” (Kames 1976, 121), each and every one in complete contradiction to human nature, and at the same time a petitio principii. “[The] great philosophers take no pleasure to dissect the human heart; though that anatomy be necessary for unfolding the true system of nature. They love to surprise the world with some pompous system, entirely of their own [fancy].” (Kames 2005, 88)

To come now upon the title of this post, it is indeed the tell-tale heart which shows most clearly for these 18th century philosophers the exaltation of man above beast. I invite you to read the short story of the same title, by Edgar Allen Poe, and while reading it keep in mind the following passage from Kames:

What is above laid down is an analysis of the moral sense … [T]he more we search into the works of nature, the more opportunity there is to admire the wisdom and goodness of the Sovereign Architect. In the matters above mentioned, performing of promises, gratitude, and abstaining from harming others, we have not only the peculiar feeling and sense of duty and obligation: in transgressing these duties we have not only the feeling of vice and wickedness, but we have further the sense of merited punishment, and dread of its being inflicted upon us. This dread may be but slight in the more venial transgressions. But, in crimes of a deep dye, it rises to a degree of anguish and despair. Hence that remorse of conscience, which histories are full of, upon the commission of certain crimes, and which proves the most severe of all tortures. … no sooner does [the guilty person] fall into distress, or into any depression of mind, than his conscience lays fast hold of him; his crime stares him in the face; and every accidental misfortune is converted into a real punishment. (Kames 1976, 64–65)

* Or so he tells us; I have yet to independently verify this claim, for example by dissecting a porpoise in a local café, as was done by Robert Hooke and Edward Tyson (the father of comparative anatomy). Which would show to us, as Tyson’s famous Anatomy of a Porpess (1680) tells us, that the pericardium is indeed fastened to the diaphragm in other animals also. 

** John Ray then goes on to tell us that men can produce milk just as well as women can, and that during sleep our muscles inflate like balloons to form soft cozy pillows (to this, Cotton Mather, commenting on the same issue, exclaims gleefully “Oh merciful God, thou makest my bed for me!”) – but these are topics best left for another time.

*** Interestingly, in the 3rd edition Kames changed this expression to “…give fair play to what passes in the mind” (Kames 2005, 33).

**** In fact, all design arguments and all knowledge of God is grounded in our emotions and feelings; we do not need reason to find God, for “within the heart of man, [He] has placed [his] lamp” (Kames, 392)

 

Bibliography

Boyle, Robert. 1688. A Disquisition About the Final Causes of Natural Things. London: H.C.

Derham, W. 1786. Derham’s Physico and Astro Theology: Or, A Demonstration of the Being and Attributes of God. London: J. Walter.

Kames, Henry Home. 1976. Essays on the Principles of Morality and Natural Religion. British Philosophers and Theologians of the 17th & 18th Centuries. New York: Garland Pub.

———. 2005. Essays on the Principles of Morality and Natural Religion: Several Essays Added Concerning the Proof of a Deity. Edited by Mary Catherine Moran. 3rd ed. Natural Law and Enlightenment Classics. Indianapolis, IN: Liberty Fund.

Ray, John. 1743. The Wisdom of God Manifested in the Works of the Creation. 11th ed. London: Printed for W. Innys.

Waal, F. B. M. de, Stephen Macedo, Josiah Ober, and Robert Wright. 2006. Primates and Philosophers: How Morality Evolved. The University Center for Human Values Series. Princeton, N.J: Princeton University Press.