Why Biology Might Reclaim Classical Causation
Aristotle (ca. 384-322 b.c.) was a comprehensive thinker who wrote extensively on biology, physics, astronomy, and other natural sciences, as well as on logic, rhetoric, literary theory, politics, and ethics. His works have been studied almost continuously by serious minds for over 2,000 years. If we measure old books by their continuing influence, then the books of Aristotle belong in the elite class, along with the Bible, the dialogues of Plato, and the plays of Shakespeare.
In some fields, Aristotle's thought has remained influential up to the present day. Nonetheless, in the area of natural science, Aristotle's reputation has taken a number of hits. After the time of Descartes and Bacon, his ideas were systematically expunged from physics and astronomy; after Darwin, they were eliminated from biology. Thus, while today one can't be a responsible political or ethical theorist without being familiar with the works of Aristotle, one can be a successful scientist without having read a line of his writings.
Aristotle's Four Causes
To the modern natural scientist, the main flaw in Aristotle's science is its account of causation. To understand why modern science objects to this account, we need to understand what Aristotle claimed. A systematic exposition is found in his central work on natural science, the Physics (Book II, Chs. 3-9):
[W]e should look into the question of how many causes there are, and what they are like. For the point of our investigation is to acquire knowledge, and a prerequisite for knowing anything is understanding why it is as it is, in other words, grasping its primary cause. Obviously, then, this is what we have to do in the case of . . . natural change in general. . . .
One way in which the word "cause" is used is for that from which a thing is made . . . for example, the bronze of a statue, the silver of a bowl. . . .
A second way in which the word is used is for the form or pattern. . . . For example, the ratio 2:1 . . . cause[s] the octave.
A third way in which the word is used is for the original source of change or rest. For example, the deviser of a plan is a cause, a father causes [i.e., begets] a child, and in general a producer causes a product and a changer causes a change.
A fourth way in which the word is used is for the end. This is what something is for, as health, for example, may be what walking is for. If asked, "Why is he walking?", we reply, "To get healthy", and in saying this we mean to explain the cause of the walking. . . .
These are more or less all the ways in which we use the word "cause." The upshot is that there are a number of ways in which the word is used and also that a single thing has a number of causes. . . . For instance, both sculpturing and bronze are causally responsible for a statue . . . one is a cause in the sense that matter is a cause, while the other is a cause in the sense that the source of change is a cause.
In this passage we see Aristotle's "four causes," usually called "material," "formal," "efficient," and "final." The bowl is made of silver, so its material cause is silver; in an octave the ratio between the pitches of the two notes is 2 to 1, so that ratio is the formal cause of the octave; the father's seed is what produces the child, so it is the "efficient cause" of the child's existence; and health is the motivation for walking, so health is the end, purpose, or "final cause" of walking.
This is clear enough, but it's odd that almost all of Aristotle's examples of "causes" are drawn not from nature but from the human world. Didn't he say he was writing about the causes of "natural change"?
One could regard his examples as analogies, enabling his readers to apply their experience of human affairs to understand the non-human world of nature. But they are more than analogies, for in Aristotle's view all four of the causes are actually operative in the non-human world. So, for example, when an acorn becomes an oak tree, there is a material cause (the matter which the growing plant ingests from the ground), an efficient cause (the active seed inside the acorn), a formal cause (the immaterial "form" of the oak tree which organizes the matter into an actual oak tree), and a final cause (the striving of the acorn to become an oak tree, which is the natural end of its growth). And for Aristotle all of these causes are necessary to provide an exhaustive explanation for the origin of the oak tree. One cannot fully understand why the oak exists without acknowledging all four causes as genuine causes.
Two Causes Down
This is precisely where modern science took issue with Aristotle. Starting with Bacon and Descartes, philosophers began to doubt the usefulness of formal and final causes in explaining natural phenomena. It became normal for natural philosophers (later called "scientists") to explain things solely in terms of material and efficient causes, especially the latter. Thus, early modern physics rejected Aristotle's notion that heavy ("earthy" or "watery") bodies naturally tended downward, toward the center of the earth, whereas light ("airy" or "fiery") bodies naturally tended upward, toward the heavens; unintelligent bodies did not "strive" toward any ends, but acted solely due to universal forces which applied to all matter, heavy or light. By the eighteenth century no respectable physicist or astronomer tried to explain the motion and changes in inanimate objects in terms of "forms" or "ends" that directed those objects.
Biology was slower to reject formal and final causes, for the very simple reason that living things did seem to have both architecture and purpose built into them. The idea that the acorn was actualizing the form of an oak tree, and even "striving" to become an oak tree, was intuitive and not easy to shake off. It took Darwin's theory of evolution to change the intellectual landscape of biology.
Darwin provided an explanation for the origin of living things which seemed to prove that the "forms" and "ends" in living things were illusory; for the Darwinian, new species arose not because God had created any new "form" for those species, and not because there was any "end" directing the -arrangement of their parts, but because accidental variations had enough survival value to be "selected" for future reproduction. It seemed as if nature arranged matter into certain forms and tailored matter to certain ends, but that was an illusion. After Darwin, biologists were convinced that all they needed were material causes (e.g., cells, molecules such as DNA) and efficient causes (variation, mutation, selection) to explain the origin and character of any living thing. That was the reigning opinion of twentieth-century biology.
However, the ideas in the old books have a way of bouncing back, and the ideas of formal and final cause found in the Physics appear to be making a comeback. Some modern biologists are consciously using the language of inbuilt form and/or inbuilt ends in explaining biological systems. One such biologist is J. Scott Turner, whose books, including The Tinkerer's Accomplice (2007) and Purpose and Desire (2017), make a case for a modern, scientifically updated version of Aristotle's formal and final causes. To be sure, such neo-Aristotelianism is still a minority view among biologists, but the fact of its emergence, after over a century of frankly reductionist and materialist biology, is testimony to the enduring relevance of Aristotle's thought.Cameron Wybrow
received his Ph.D. in Religious Studies from McMaster University in Hamilton, Ontario. He writes on education, politics, religion, and culture.This article originally appeared in Salvo, Issue #44, Spring 2018 Copyright © 2019 Salvo | www.salvomag.com https://salvomag.com/article/salvo44/darwin-vs-aristotle-20