Evolutionary theory can be a nasty business. Perhaps it has something to say about human nature.
Most scientifically respectable evolutionary theories wear garments of math. I think of mathematical models as disciplined metaphors. We use x to represent something in the world, say slugs, and y to represent something else, say lettuces, then we analyze the relation of x to y using mathematics. We imagine that slugs and lettuces behave like x and y in the model, and then we use how x and y behave in the model to understand how slugs and lettuces behave in the world. Nobody can argue with mathematical models—that is one of the points of using mathematics—but there can be endless arguments about what you put into a model and what you leave out, and endless arguments about what the model means, because metaphors can be interpreted in many ways. I am not criticizing the use of metaphors—far from it, they are essential. All that we know about the world is metaphor. Our perceptions are a virtual reality, not the thing in itself but something that stands in the place of the thing. Phenomena are metaphors used to comprehend things. Don’t worry, this book contains almost no mathematics; but, if you don’t like metaphor, then this is probably a good time to return the book and ask for a refund.
As an undergraduate, I was exhorted to eschew intentional idioms and, forty years later, I am still admonished for my “unscientific” language by anonymous reviewers who believe devoutly that such language should be suppressed. The moral tone in these criticisms suggests something important is at stake. Nobel Prize winners in the audience roll their eyes when I give public lectures. I am told that my choice of words expresses everything that is “soft” and unscientific about adaptationism as compared to the “hard” and rigorous sciences (rigor is stiffness in Latin). But when you listen closely to my critics, their own language abounds with reference to codes, signals, messages, and the like. When challenged, these tough-minded empiricists insist that these terms have strict physical meanings that do not invoke purposes. Most would reject, as absurd, a claim that they were using metaphor.
If it were only about words, I would have had better things to do than write this book, and you would probably have better things to do than read it. I do not mean to disparage words. Spoken and written language are the expression of deep inner structures. The language that is censored says something about the values and fears of the censor. This book pays close attention to the meanings of words for four main reasons. The first is that languages evolve and provide useful analogies for thinking about genetic evolution. For example, the original reasons for particular turns of phrase can be forgotten, e.g., exempli gratia. The second is that meaning is the outcome of a process of interpretation and is specific to each interpreter. The same words will be interpreted differently and mean different things for each reader. As a result, many acrimonious disputes in the philosophy of biology are really quibbling about definitions rather than disputes about facts. The third is that the origin of language marked an extraordinary expansion in the lexical expressivity of the flux of meaning. The fourth, and most important, is that the beauty and diversity of language, like the beauty and diversity of the natural world, are wonders to behold.
Over the years I have come to believe that many promising approaches in biology, some of agronomic or medical significance, are not pursued because they violate the philosophical presumptions of working biologists who are unaware of their own presumptions. Good ideas are rejected for bad reasons. The money that goes into publicly funded research could be better spent. I see the denial of a naturalized teleology—a teleology grounded in the powerful metaphor of natural selection—as one of these self-defeating presumptions. It is a refusal to acknowledge the obvious, that organisms do things for good reasons.
The admonition that teleology has no place in science can be traced to the seventeenth century and the rejection of final causes as useful explanatory principles at the beginning of the Scientific Revolution. Final causes were one of the four categories of Aristotelian causes that had been a mainstay of medieval philosophy. In very rough terms, the material cause was the stuff out of which a thing was made; the formal cause was that which made of this stuff one kind of thing rather than another; the efficient cause was that which set a thing in motion; and the final cause was the purpose or end (telos), that for the sake of which the thing existed. The new materialist philosophy embraced material and efficient causes (matter in motion) but rejected final causes and had an ambivalent relation to formal causes. Lurking in the background was a separation of facts from values. An important scientific value was that facts were more important than values (irony intended), but if we were true scientists we should want to understand the origins of values and meanings.
The main task of this book is to explain how a physical world of matter in motion, of material and efficient causes, gave rise to a living world of purpose and meaning, of final and formal causes. I will briefly sketch the book’s arguments so that you have some sense where it is heading. The key development in the history of life was the origin of writing, of materials that were copied and had effects in the world that directly or indirectly influenced a copy’s chance of being copied. These genetic materials do not create new matter from the void but rearrange existing matter to match a model. The successive copies are material things, not incorporeal ideas, but lineages of material genes preserve structure despite perpetual change in molecular substance. What is “communicated” from model to copy? One may call it information or simply form. Genetic materials can be considered formal causes. Aristotle would have said that the formal cause of our being human is that which makes of our material cause a human being. Human, chimpanzee, and slug bodies are built of the same materials but have different forms. Our bodies are more similar to the bodies of chimpanzees than to the bodies of slugs because we share more evolutionary history with chimpanzees than with slugs (one might say our formal causes are more similar).
But copying alone does not get us anywhere: garbage in, garbage out. We want to feed in garbage at one end and obtain something useful at the other end (an egg perhaps). Let’s speak of eggs. Spinoza expressed a commonsense objection to final causes: the “doctrine of Final Causes turns Nature completely upside down, for it regards as an effect that which is in fact a cause, and vice versa. . . . It makes that which is by nature first to be last” (2002, 240). Common sense tells us that causes cannot come after their effects and a final cause appears to explain an earlier something by a later something, the goal the earlier something is intended to achieve. But common sense extrapolates an uncontroversial property of causes of particular events to a problematic restriction on causes of types of events. My favorite example, which will recur as a leitmotif throughout this volume, concerns chickens and eggs. It is unproblematic to ask whether this particular chicken was a cause of this particular egg. If the egg developed into the chicken, then the egg is a cause of the chicken. If the chicken laid the egg, then the chicken is a cause of the egg. But the question becomes problematic when we ask how generic chickens are causally related to generic eggs, because chickens then occur both before and after eggs. Eggs exist for the sake of becoming chickens and chickens for the sake of laying eggs.
Final causes emerge from replicative recursion by the process we call natural selection. Genes and their effects are like eggs and chickens. A gene’s effects have a causal role in determining which genes are copied. A gene (considered as a lineage of material copies) persists if its lineage has been consistently associated with survival and reproduction. If possession of a gene is consistently associated with survival and reproduction then one can infer that the gene’s effects have causally contributed to the gene’s persistence. (A gene does not achieve anything except in the context of other genes and environmental inputs during a single life but, over the course of many generations, each gene is shuffled onto random backgrounds of other genes and this randomization allows natural selection to “infer” causation from correlation.) If past effects that have contributed to a gene’s persistence are recapitulated as effects of a current gene, then these effects exist for the sake of their cause and can be considered the gene’s raison d’être (or final cause). As a consequence of differential replication of alternatives, successful genes accumulate information about what has worked in the past. This information comes from the environment that selects.
From this perspective, natural selection can be viewed as inductive reasoning about effective action: a gene’s effects are hypotheses about what works in the world, with confidence in a hypothesis increasing with the strength of past associations with favorable outcomes. But there is no guarantee that the world will not change. As David Hume wrote about inductive reasoning: “All inferences from experience suppose, as their foundation, that the future will resemble the past, and that similar powers will be conjoined with similar sensible qualities. If there be any suspicion that the course of nature may change, and that the past may be no rule for the future, all experience becomes useless, and can give rise to no inference or conclusion” (1748/2004, 22). What worked in the past need not work in the present because the world may have changed.
But surely, some will argue, evolutionary intentionality is ersatz intentionality, a metaphor, not the real thing. Only beings like us have real intentions because only we can foresee the future. But we cannot know the future. There is no backward causation. Our intentions are anticipated outcomes. When I act with intention, I have an outcome in mind. My deliberation is past and my plan may misfire. The unintended products of natural selection can likewise be considered agents whose bodies and instinctive behaviors “anticipate” that what has worked in the past will work in the future.
There remains a metaphysical sense in which all bodies of living things—including our own—can be considered nothing but matter in motion. Material causes of intricate structure have been shaped by unknowably complex chains of efficient causes that were set in motion before the origins of life. But this is a declaration of faith, not a practical procedure for understanding the world. Formal and final causes are human tools—furnaces and engines of discovery—that are both practical and fruitful for understanding living things. Their rejection as explanatory principles for biology throws the baby out with the placenta. The commandment of my undergraduate educators, thou shalt not use teleological language, is no more than a dogmatic insistence on ritual purity.
The intentionality of natural selection is retrospective. But what worked in the past was observing the present and predicting the future. Organisms have evolved to be real-time interpreters of their worlds, to be users of information about the world to guide effective action in the world. Organisms deliberate and decide. The latter chapters of this book define meaning as the output of a process of interpretation, but I cannot fully justify that claim here. It is what the book is about. I will argue that there is a continuum from the very simplest forms of interpretation, instantiated in single RNA molecules near the origins of life, to the type of interpretation that is going on in your mind as you skeptically evaluate this sentence. My hope for this book is that an appreciation of this continuum of meaningful interpretation will help to reunite the humanities and sciences in a continuum of intellectual endeavor. I hope you give me a chance to make my case.
So far I have talked about the book’s contents and goals, but it would also help to say something about its form. This book is intended to mirror the products of natural selection, which themselves mirror the creative process. And this intention, like the products of natural selection, was partly retrospective. I began to compile a collection of previously published and unpublished papers that I needed to tweak at the margins so that they worked together as a whole but soon recognized that my editorial choices were a metaphor of the evolutionary process. When I first wrote the texts that comprise this book I could not know my final destination. Natural selection similarly has no purposes or preordained ends but creates beings with intended meanings. It acts to solve small local problems but, in the process of solving small problems, it inadvertently solves larger problems because everything it does is inadvertent. I have spent most of my life attempting to solve small local difficulties in evolutionary theory but hope in the process to have solved some larger problems.
Natural selection reuses old materials for new purposes. Its products are thereby comprised of parts of variable age that nevertheless must work together in some more-or-less coherent fashion. The resulting genomes are pastiche and so is this book. Its bricolage extends to the extensive use of quotations and paraphrase. If something has been said well, use it again. There is a saving of literary labor just as there is a saving of evolutionary labor. Darwin understood this principle well in a discussion of how old wheels, springs, and pulleys (slightly altered) can be repeatedly reused for new purposes, and I will repeatedly reuse his metaphor. One reason for not starting at the beginning and attempting to write a fully coherent whole that expresses how I see the world now is that I am a constantly changing fiction I tell myself. Some of my earlier selves may have understood the issues more clearly than I do now.
This book was not started at the beginning and written through to the end with the oldest bits first and the newest bits last. If you choose, you can read it the same way, skipping ahead and then coming back for a second reading. In some of the chapters, I descend into messy biochemical details rather than provide a highly simplified version (although my scientific readers will consider my presentation highly simplified). You may choose to scan these sections without trying to comprehend the details, because my principal intent is to show the underlying complexity of some of the simplest things we do. But if you get the deconstructionist bug for following the flux of meaning in biological bodies, you might give a close reading to how internal messages are continuously reinterpreted in new molecular media. Finally, I believe that the humanities and sciences have much to say to each other, so I wished to express my ideas in a style that would engage both audiences at the risk of enraging both and being ignored by both. Much of the prose was originally written under the constraints of meeting the selective criteria of scientific reviewers, and it shows. But the freedom from these constraints as I have revised the text has been liberating.
One of the unintended outcomes of thinking about what I meant by a gene was a new way of thinking about meaning. Meaning does not reside in the input to the reader but in the output: whatever the reader interprets a text to mean. I hope that some of your interpretations will be both complimentary and complementary, but once a text has been written its meanings reside with its readers. This book does not claim to have discovered a “truth” but to present ways of thinking about the world, and of interpreting words, that I have found useful and hope you might find useful.
Don’t know much about history
Don’t know much biology
Don’t know much about a science book,
Don’t know much about the French I took
But I do know that I love you,
And I know that if you love me, too,
What a wonderful world this would be.
—Sam Cooke, Lou Adler, Herb Alpert