Thursday, July 21, 2016

Lucretius in the Evolution/Creation Debate

From ancient Greece and Rome to the present, one of the fundamental debates in human history has been over a deep question: Is our universe mindful and purposive or mindless and material?  Do we live in a cosmos that was intentionally created by a divinely intelligent designer who cares for us and judges us by his moral law?  Or do we live in a cosmos that arose unintentionally by natural evolution through chance and necessity with no concern for us or any moral law?

Today, this debate is between the creationists or intelligent design theorists, on the one side, and the Darwinian evolutionists, on the other side.  Some theistic evolutionists (like Francis Collins or Owen Gingerich, for example) have tried to take a third position: that the Creator has designed the parameters of certain natural constants so that cosmic evolution is fine-tuned for producing intelligent human life as the fulfillment of the Creator's purposes.

In ancient Greece, some of the pre-Socratic natural philosophers (like Empedocles and Democritus) developed materialist or mechanist explanations for how the world and all living beings in it could have emerged by natural causes without any divine design or purpose.  In some of Plato's dialogues--particularly in book 10 of the Laws and in the Timaeus--this anti-teleological cosmology was rejected as a dangerous atheism that would subvert the moral and political order of human life. Plato's Athenian Stranger (in the Laws) argues that everyone in the political order he proposes must believe that the gods exist, that the gods think about and care for human beings, and that the gods enforce justice by rewarding the good and punishing the bad.  Those people who openly question this cosmic theology should be imprisoned, and if they cannot be persuaded to accept this theology, they will be punished with death.  Plato's Timaeus argued that people should be taught that everything was created by a divine Demiurge or Craftsman assisted by other gods according to a model of an eternally enduring nature, so that the cosmos could be seen as the best of all possible worlds.

Later, Epicurus challenged this Platonic cosmic teleology by developing his own anti-teleological cosmology based on the atomistic science of Democritus.  Everything could be understood as the patterns of order arising from the combining and dissolving of atoms moving in a void, so that all possible combinations of these atoms would arise as worlds coming into being and passing away.  All life is mortal, so there is no afterlife, and no divine judgment of human beings after death. The gods exist, but they live outside the world of human experience, and they do not care for or intervene in human affairs.  All of the organized religions that teach that the gods have created the world and judge human beings both in this life and in the afterlife deprive human beings of happiness by promoting a fear of death and of divine judgment that creates unnecessary and unreasonable anxiety.

Epicureans can be happy because they don't fear god, they don't worry about death, they know that the goodness of pleasure is usually easy to get, and they know that the badness of pain is usually easy to endure.  This is possible because their freedom from religious fears and their understanding of how everything is ultimately explained by natural causes allows them to live out their mortal lives with tranquil minds.

Although Epicurus wrote many books, most of his writing has been lost, and we now have only fragments quoted by other writers.  The most extensive text of Epicurean philosophy is the Latin philosophical poem of Lucretius--De Rerum Natura (On the Nature of Things)--which he wrote sometime before his death in 55 B.C.  Although he does not mention Plato by name, Lucretius can be seen as defending the Epicurean anti-teleological cosmology against the Platonic teleological cosmology, particularly as it was reformulated by the Stoics.

Christian theologians were able to accept modified forms of the Platonic and Stoic cosmology of divine creation as compatible with Biblical creationist theology, which became the predominant model of the cosmos in Christendom for over 1,500 years.  But Christians had to scorn the Epicurean/Lucretian cosmology of materialist atomism as promoting a dangerously atheistic view of the universe. 

The texts of Lucretius' book were either destroyed or hidden away, until a text was rediscovered in 1417 by Poggio Bracciolini.  Many early modern philosophers and scientists could then see the Lucretian materialist and anti-teleological model of the cosmos as the alternative to the creationist and teleological model of Christian cosmology.

Finally, with the publication in 1859 of Charles Darwin's On the Origin of the Species, the Darwinian theory of the evolution of species by natural selection in the struggle for survival seemed to provide a modern scientific version of Lucretian cosmology as an alternative to Christian creationism.  If so, then the debate between evolutionists and creationists today continues the debate between Platonists and Epicureans over whether the cosmos has been intelligently and purposefully designed or not.

As I have indicated in some previous posts, this cosmological debate is also a moral and political debate, because while the Platonic/Christian cosmology of order as a top-down imposition of intentional planning seems to support moral and political authoritarianism, the Epicurean/Darwinian cosmology of order as a bottom-up emergence of spontaneous order seems to support moral and political liberalism.

 But is it really true that the Epicurean cosmology of Lurcretius' book conforms to a Darwinian evolutionary conception of the universe?  Gordon Campbell (a classics scholar) has helped me to think about this through one of his papers--"Zoogony and Evolution in Plato's Timaeus: The Presocratics, Lucretius, and Darwin" (2000)--and one of his books--Lucretius on Creation and Evolution (2003).  Campbell's writing illuminates Lucretius' place in the evolution/creation debate from ancient Greece to the present.

And yet I do disagree with Campbell on four points.  First, I disagree with his claim that the only "fully evolutionary theory" of the cosmos in the ancient world is in Plato's Timaeus (Campbell 2003, 2).  He distinguishes between two kinds of evolution (Campbell 2000, 14).  "Inter-specific evolution" is "the Darwinian model of the origin of species by the gradual accumulation of variation over time leading to the formation of new species."  "Intra-specific evolution" is "the accumulation of variation within a species that stops short of crossing species boundaries."  He claims that Plato is the only ancient proponent of Darwinian inter-specific evolution, because Plato's Timaeus describes an evolutionary process in which the Demiurge first creates human beings and then morally degenerate human beings evolve into four kinds of animals--birds, footed land animals, footless land animals, and fish--with the animals ranked from the more thoughtful animals to the thoughtless animals.

The first problem with Campbell's claim is that what Timaeus describes is not a natural evolutionary process at all, because he asserts it to be the work of divine creation by the Demiurge and the other gods (Timaeus 41a-d, 92c).

The second problem is that it's not clear that Plato or Plato's Socrates endorse Timaeus's story of cosmic creation.  Timaeus's story is so utterly ridiculous that many readers have doubted that Plato takes it seriously.  A. E. Taylor, for example, made this point, but Campbell casually dismisses this and insists that Timaeus's story must be seen as a serious teaching of Plato (2000, 158).  But Campbell doesn't explain the many strange features of this dialogue.  First of all, it's not much of a dialogue.  After some brief exchanges between Socrates and Timaeus, Timaeus launches into a long lecture that takes up most of the book.  Socrates remains silent, which suggests that Timaeus's story cannot withstand any Socratic questioning. Timaeus says that his story will be a "likely myth."  Socrates says that it will be a nomos--a song, a custom, or a law (Timaeus 29d).  So Timaeus's story is not a reasoned account of the cosmos.

Moreover, what Timaeus says is often self-contradictory.  For example, Timaeus says that the best account of astronomy depends on sight--looking at the stars and the Sun--and this shows the primacy of our eyes for our knowledge of the world (47a-c).  But then he condemns as "light-minded" the empirical astronomers who believe that our knowledge of astronomy must begin with what we can see with our own eyes.  Such people are punished by being turned into birds (91d-e).

My point here is that Campbell does not consider the possibility that while Plato might have thought that a teleological cosmology of divinely intelligent design could be a salutary belief for many people, it could not be a rational account of the cosmos for natural philosophers.  Aristotle suggested this in observing that such cosmic myths were little more than traditional folk tales (On the Heavens, 270b1-25, 283b26-284b5, 291b24-292a20, 298b6-299a2; The Movement of Animals, 699b12-31; Metaphysics, 1050b20-25, 1074b1-14).

Not only do I think Campbell is wrong in identifying Plato as an evolutionist, I also think he is wrong in denying that Lucretius was an evolutionist.  This is my second point of disagreement.  Although Campbell is right in noting that Lucretius never explicitly affirms the "inter-specific evolution" of a new species from an ancestral species, Lucretius does at least implicitly suggest that human beings have evolved from an earlier species that was human-like but not fully human, because it did not have the human digestive system that requires food cooked with fire.  Lucretius could not explicitly elaborate this idea, because he lacked the evidence for human evolution that is available today--including the fossil record, the archaeological record, human physiology, and comparative primatology.

In Book 5 of De Rerum Natura, Lucretius explains the origin of all living beings as the spontaneous generation of life from the Earth (5.785-1012).  Just as today we can see the spontaneous generation of worms and cicadas from the Earth, Lucretius claims, we can imagine that at the beginning the Earth was so fertile that it could generate all forms of plant and animal life (2.871-72, 898-901, 928-29, 3.719-36, 5.797-98).  For this reason, Lucretius observes, the Earth has rightly been called the Mother of all life.

At first, the Earth experimented with many monstrous animal bodies with grotesque appearance--such as animals that were both male and female, animals without feet or hands or mouths.  These forms of life "were created in vain," because nature extinguished them.  They died from starvation. Or they could not reproduce. Or they could not compete with other animals.  Only those species adapted for survival, reproduction, and competition were naturally selected for preservation.  Those human beings who lived in these early days were tougher and larger than human beings today.  They lived as solitary foragers and like savage beasts, with no families, no farming, no customs or laws, no use of fire or clothing.  Men and women came together for sexual copulation and then separated with no enduring attachment.  (Here is where Rousseau found his first "state of nature" of "nascent man" for his Discourse on the Origin of Equality.)

Some modern commentators have argued that this Lucretian account of the origin life is refuted by modern science.  One criticism is that Lucretius speaks mythically of Mother Earth as a teleological creator.  Another criticism is that the belief in the spontaneous generation of life was refuted by Louis Pasteur's famous experiments showing that living organisms cannot arise spontaneously from lifeless material.  A third criticism is that the modern fossil and archaeological record shows an evolution from simple forms of life to more complex forms, including a human fossil record showing human evolution over millions of years, which denies Lucretius's claim that all forms of life originated simultaneously and his claim that the first human beings lived as utterly solitary animals who lived on raw food without fire for cooking.

Campbell rightly defends Lucretius against the first two criticisms.  But he cannot defend Lucretius against the third criticism.  Against the first criticism, Campbell can point to clear statements from Lucretius that he uses teleological metaphors--like Mother Earth--to aid his anti-teleological message (2.655-60).  In doing this, Lucretius is like Darwin, who explained that in personifying "survival of the fittest" as "natural selection," he was employing a metaphorical expression that was not to be interpreted literally as suggesting some intentional agency or deity (see Chapter 4 of the second edition of The Origin of Species).  For Darwin, nature "selects" only in the sense that those traits that impede survival, reproduction, and competition tend to go extinct.  Similarly, for Lucretius, those forms of life that cannot survive, reproduce, or compete successfully tend to go extinct.  There is no teleological cosmic plan guiding this evolutionary process.

To answer the second criticism--that Pasteur refuted the belief in the spontaneous generation of life--Campbell rightly points out that while Pasteur's experiments showed that at present life cannot arise from lifeless material, this does not show that originally life could not have been spontaneously generated in the earlier conditions of the Earth.  Indeed, any scientific account of the origin of life from non-life through natural evolution rather than intelligent design would have to be a spontaneous generation of life.  There is today no generally accepted theory for explaining the natural origin of life, and so it remains one of the great mysteries in modern science.  But there is general agreement among scientists that any successful theory for resolving this mystery will have to find a natural mechanism for the spontaneous generation of the most primitive form of life.  For example, one popular theory today is that life originated from 3.2 billion to 3.8 billion years ago in very hot geothermal vents at the bottom of ancient oceans.  Even if this does not prove to be the correct theory, it illustrates the search for a spontaneous generation of the first life forms like that sought by Lucretius.

Campbell does not defend Lucretius against the third criticism--that his assertion that all forms of life that we see today arose fully formed simultaneously at the beginning is contrary to the evidence for the evolutionary history of life as we know it today.  Here, Campbell argues, we see why Lucretius is not truly an evolutionist in the modern Darwinian sense, because here we see that Lucretius believes in the fixity of species: although Lucretius allows for some evolutionary change within a species, he does not allow for evolutionary change by which one species evolves into another.  Species can go extinct, but all of those species that have survived to the present are essentially the same species as they were at the beginning.

Although there is good evidence for this interpretation of Lucretius, there is some ambiguity here, particularly in what Lucretius says about the origins of fire and cooking (5.955-58, 1012-20, 1091-1104).  Lucretius says that the first primitive human beings were tough enough to live on raw food like other animals.  They had no knowledge of how to use fire for cooking.  But then from observing the effects of wild fires and the warming of the Sun, they learned how to cook their food, which was part of a suite of changes that allowed them to live in family settlements that made them fully human for the first time.  In his comments on this section of Lucretius's poem, Campbell observes: "Humans become truly human, and finally civilized when they have been mastered by fire, marriage, and love, and when they in turn master nature with new technologies.  Fire and cooking were chief among these" (2003, 329).  This shows the "process of becoming fully human" (2000, 154-55).

Doesn't this imply that those first primitive human beings who lived totally on raw food were not "truly human" at all, and so what we see here is evolution from a non-human but somewhat human-like animal species to a fully human species?  If so, then this points to human evolution as inter-species evolution.  Lucretius could not elaborate this idea explicitly because he did not have all of the empirical evidence available today for human evolutionary emergence from primate ancestral species.

That evidence--from fossils, archaeology, primatology, and evolutionary anthropology--confirms the truth of Lucretius's insight about the importance for human evolution of controlling fire for cooking.  Richard Wrangham has surveyed this evidence in support of his "cooking hypothesis" for explaining human evolution (Wrangham 2009; Gowlett and Wrangham 2013).  No human societies have ever relied on raw food for most of their diet.  And no human beings have been known to survive for more than a few weeks by eating only wild raw food.  Unlike every other animal, human beings need a large portion of their food to be cooked.  Compared with the great apes, human beings have a reduced digestive system--small molars, mouth, stomach, and large intestine--that is adapted for digesting cooked food.  Moreover, the brain is a metabolically expensive organ that requires lots of energy; and therefore the increase in the size of the brain that characterizes human evolution required a reduction in gut size and energy costs and the consumption of higher quality cooked foods to reduce the metabolic constraints on brain size by delivering increased energy to enlarged brains.  The evidence of the hominin fossils indicates that Homo erectus had such enlarged brains that would have required digestive systems needing cooked food.  There is also some archaeological evidence for the controlled use of fire appearing at around 1.5 million years ago, at the time of the first major increase in the brain size of early Homo.  All of this evidence suggests that what Lucretius describes as a transition from primitive humans living "in a manner like wild animals" (more ferarum) (5.932) without fire and cooking to fully human beings living with fire and cooking was actually an evolutionary transformation from a pre-human species to a truly human species.

According to Campbell, "Lucretius' early humans evolve in response to their changing environment, but they are still unable to cross the species barrier imposed by the atomic laws of nature (foedera naturae); they evolve but remain within their own species" (2000, 155).  Does this mean that there can be a major change in the physiology and anatomy of the digestive system without a change of species?  Or should we say, in the terminology of modern taxonomy, that there has been a change of species but not of genus?

Campbell says that the evolution here in Lucretius is not Darwinian evolution but Lamarckian evolution, because it's the evolution of acquired characters.  Contrary to what Campbell assumes, Darwin accepted Lamarckian evolution.  Today, some evolutionary theorists would say that there are at least four levels of evolutionary inheritance--genetic, epigenetic, behavioral, and symbolic (Jablonka and Lamb 2014).  Could we explain what Lucretius describes here as genetic/behavioral coevolution?

Oddly, while Campbell argues that Lucretius was not a Darwinian evolutionist, he also argues that Lucretius was a better evolutionist than was Darwin!  This is my third point of disagreement with Campbell.  According to Campbell, Lucretius suggests that evolutionary adaptation in the struggle for life can occur at five levels--survival, reproduction, competition, competition avoidance, and cooperation.  Campbell thinks that Darwin recognizes the first three levels but not the last two (Campbell 2003, 119-23, 129, 252-61).  I disagree.  Lucretius claims that human beings could not have survived if they had not learned to cooperate: "It was then that neighbors, in their eagerness neither to harm nor be harmed, began to form mutual pacts of friendship, and claimed protection for their children and women, indicating by means of inarticulate cries and gestures that everyone ought to have compassion for the weak" (5.1019-23). 

Campbell sees this idea as confirmed by recent work (by Robert Axelrod and others) on the evolution of cooperation, but he does not see this idea was first elaborated by Darwin in his account of the evolution of the "moral sense" in The Descent of Man.  All of the recent thinking about the evolution of cooperation through kin selection, reciprocity (direct and indirect), and group selection is building on Darwin's thinking in Descent.

Lucretius also recognizes the human domestication of animals as mutually beneficial for the animals and human beings (5.862-78).  Campbell identifies this as "extinction avoidance through symbiosis and the survival advantages of becoming tame" (2003, 129).  This also was well studied by Darwin, particularly in his Variation of Animals and Plants Under Domestication (1868).

My final point of disagreement with Campbell concerns his understanding of teleology.  He is right in seeing that modern Darwinian biology agrees with Lucretius and the Epicureans in their anti-teleological view of the cosmos as a spontaneous order that has not been designed to serve any purpose.  But only obliquely does Campbell recognize that modern biology can affirm immanent teleology while denying cosmic teleology (Campbell 2000, 152, 170-71).  Although the evolutionary process does not serve goals, the organisms emerging from that process do.  Reproduction, growth, feeding, healing, courtship, parental care for offspring--these and many other activities of organisms are goal directed.  Biologists cannot explain such phenomena unless they ask about ends or purposes immanent in the evolved nature of the species.  This allows for a biological understanding of morality as natural right or natural law rooted in the immanent teleology of evolved human nature.


Campbell, Gordon. 2000. "Zoogony and Evolution in Plato's Timaeus: The Presocratics, Lucretius, and Darwin." In M. R. Wright, ed., Reason and Necessity: Essays on Plato's Timaeus, 145-80. Swansea, UK: The Classical Press of Wales.

Campbell, Gordon. 2003. Lucretius on Creation and Evolution: A Commentary on De Rerum Natura, Book Five, Lines 772-1104. Oxford: Oxford University Press.

Gowlett, John A. J., and Richard W. Wrangham. 2013. "Earliest Fire in Africa: Towards the Convergence of Archaeological Evidence and the Cooking Hypothesis." Azania: Archaeological Research in Africa 48: 5-30.

Jablonka, Eva, and Marion J. Lamb. 2014. Evolution in Four Dimensions: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life. Revised edition. Cambridge: MIT Press.

Wrangham, Richard W. 2009. Catching Fire: How Cooking Made Us Human. New York: Basic Books.

Some of these points are elaborated in other posts here, here, here, here, here, here, here, here, here, here, here, here, here, here., and here.


Anonymous said...

"In some of Plato's dialogues--particularly in book 10 of the Laws and in the Timaeus--this anti-teleological cosmology was rejected as a dangerous atheism that would subvert the moral and political order of human life. "

" Epicurus challenged this Platonic cosmic teleology by developing his own anti-teleological cosmology...All of the organized religions that teach that the gods have created the world and judge human beings both in this life and in the afterlife deprive human beings of happiness by promoting a fear of death and of divine judgment that creates unnecessary and unreasonable anxiety."

So the choice is between subverting the moral and political order of human life, or anxiety. Wow. Tough choice.

CJColucci said...

Not really. The choice is between something false -- that moral and political order needs a divine teleological source -- and something true -- that the fear of everlasting torment creates anxiety.