Questions for a Forum on Evolution

1. Explain the process of evolution

A story: There’s a group of creatures, about half are green, half white. They migrate to a place covered in green grass. It’s easier for predators to find the white ones than the green ones. More white ones get eaten before they have a chance to have babies. When a green creature has babies, they are usually green too, though occasionally a green mother gives birth to a white baby. When a white mother has babies, they are usually white too, though occasionally a white mother gives birth to a green baby. Once in a while, a white gets lucky and lives long enough to have babies, and sometimes predators get lucky and eat a green before it reproduces. But it’s no surprise when, after many generations, there are proportionally fewer whites and more greens. Eventually, almost all of them are green. It’s as though the environment, the green grass and the predators, have selected the greens for life and the whites for death. But no one intentionally selected anything; it was just nature: natural selection. Over many generations, these creatures have adapted to life in their green and grassy place.

The world does not stand still. At first, winter in the land of green grass was hardly noticeable. The climate begins to change and most years the snow lasts longer than the year before. The greens are easy to see on the white snow but the whites, of which there are just a few, are harder for predators to find. The greens’ chances of having babies begin to decline and the whites’ chances of reproducing start to go up. Eventually, snow covers the land all year, and almost all the creatures are white. Just a few greens remain. The creatures have again adapted to their environment.

More time goes by. The creatures have spread over a wide area. Things have gradually warmed up again; the snow is gone, and they are green again. The melting snow causes the sea level to rise and a low lying area floods, cutting off some of the creatures from the rest. Conditions on the island, and on the mainland, continue to change, though in slightly different ways. Both the islanders and the mainlanders adapt, so after a while they differ from one another. The predators on the island are sea birds that fly off with their prey. At first, just a lucky few of the creatures are too large to be suitable victims, but it’s no surprise that, eventually, almost all the island creatures are too large for the birds to capture. They are now much larger than their mainland cousins. Things cool down again, the sea level drops, and the island is now a peninsula. The two groups now mingle. But now they barely recognize one another as possible mates. Island creatures tend to mate with similarly large island creatures, and the smaller mainland creatures tend to mate with other, smaller mainland creatures. The adventuresome few who ignore the difference in size find that mating attempts don’t go well. (Try breeding a Great Dane with a Chihuaha; it’s biologically possible, but awkward.) More time goes by and the two groups continue to adapt in different ways, and interbreeding becomes impossible, not just unlikely. Temporary geographical isolation has resulted in permanent reproductive isolation. What started out as one species has become two. And so it goes.

2. Explain how your field connects to evolution.

Philosophy connects to evolution in two ways:

First, the philosophy of science concerns itself with evolutionary theory as a part of science. We’re interested in how it comes up with its hypotheses, how it tests, confirms, or disconfirms them, and in the structure of evolutionary explanation. The latter gives rise to lots of interesting problems, e.g., what is the “unit of selection?”

Second, by providing knowledge about human beings, evolutionary theory bears, in some cases decisively, on traditional philosophical questions about such matters as the mind-body problem, skepticism, innate knowledge, and moral reasoning.

3. Micro vs. macroevolution?

Microevolution is evolutionary change within a species and macroevolution is change that leads to new species. Speciation is not thoroughly understood, but it’s clear that micro- and macroevolution are not essentially different processes. There is no known mechanism to prevent microevolution from causing speciation. Under the right conditions, the changes we label microevolution result in the formation of new species. The “ring species” are famous textbook examples of this.

4. Theistic v. atheistic Evolution?

Theists assert, and atheists deny, that what happens in accord with the laws of nature is God’s doing, i.e., what God does indirectly, by means of secondary causes. All theists agree that God created the human species. But we disagree about how God did so: some of us believe that he did it the way he has created most things, i.e., by means of natural causes, specifically, by means of the processes described by evolutionary biology. Other theists believe that God created the human species directly, by way of one or more miraculous interventions. (Some who purport to endorse “theistic evolution” in reality reject the view that God created the first humans by means of entirely natural processes, claiming instead that God “guides” the evolutionary process, where guidance amounts to a number of unobtrusive, but still miraculous, nudges.)

5. Why do you believe in evolution?

If evolution by means of natural section were not to occur, we’d need to explain why not, because it’s predictable, given what we know about living things: they reproduce, making good but inexact copies of themselves, the copies inherit characteristics that can raise or lower the probability, in a particular environment, of their making copies of themselves, and environments change. Starting with one relatively simple living organism, we should expect after billions of years to find a diversity of complex living things adapted to particular environments. The empirical evidence could have defeated this expectation in many ways, but it hasn’t. Indeed, support for it has been accumulating relentlessly for over 150 years. The evidence for the evolutionary explanation of the diversity, complexity, and adaptedness of living things, with natural selection as the primary causal mechanism, is now exceedingly good. In general, science is our best way to obtain knowledge, and it is unreasonable not to believe well-confirmed scientific theories. The theory that the diversity, complexity, and adaptedness of life on Earth is the result of natural selection is a very well-confirmed scientific theory.

6. How can I believe in evolution and Christianity?

A short answer:

The evidence for evolution is so good that it is unreasonable not to believe it.

The evidence for Christianity is good enough to make believing it reasonable.

There is no good reason to believe that evolution and Christianity are mutually inconsistent.

A longer answer:

Evolutionary theory’s account of the origin and by implication, the nature, of human beings coheres well with the Christian faith. Here, as in other cases, what contemporary science tells us about the world is antecedently probable from the perspective of Christian faith, i.e., the world it portrays is what we should expect to find, given the truth of Christianity. In light of what God has revealed about his creative purposes, it’s reasonable to think he would choose to achieve his ends by means of natural processes of the sort science has uncovered.

7. How do I view Scripture?

The Bible is God’s infallible revelation; whatever it teaches is true, the word of God. In it we learn that God created the world; its basic laws and initial conditions are directly due to his creative action and answer to his intentions. The latter effects of that initial act of creation, the formation of atoms, galaxies, stars, planets, and the diversity of complex living things, are what God creates indirectly.

The scientific investigation of nature, and the interpretation of the Bible, are both reliable ways of finding out about God’s creation. Neither is infallible, but scientific methods are obviously more reliable than those of biblical hermeneutics. When apparent conflict arises, it’s generally more reasonable to suspect we’ve misinterpreted Scripture than that scientific inquiry has gone wrong. Further, supposed conflicts between Scripture and science are often merely apparent and reveal, not the misreading of the Bible, but implicit commitments to dispensable philosophical theories. We should recall that our predecessors thought Copernicanism, lunar craters, and Newtonian inertia needed to be reconciled with biblical creation.

It is our good fortune to encounter conflicts between what science says and what we think the Bible says, since they push us to reconsider, and improve, our understanding of the biblical text.

Although tied to the real acts of God in the creation of this world, the Genesis creation stories are neither history nor science; they are theology expressed in poetic narrative. Much mischief arises from the fact that in colloquial English the term “literally” has come to mean “really,” so some hear the statement that these texts are not literally true as equivalent to not really true. On the contrary, they really are true, but figuratively, not literally. To take a figurative text literally is to fail to take it seriously. The not literally true story—the naked man named “Man,” the woman named “Woman” made from his rib, the talking snake, the trees bearing magical fruit—asserts the literal theological truth about the God who for our sake created the world.

8. What about the Fall and Imago Dei?

Evolution has no particular bearing on our being made in God’s image. The popular, traditional understanding is that our being made imago Dei consists in some kind of similarity of humans to God. We are, e.g., made in God’s image in virtue of being persons. Evolution is the scientific explanation of how human persons came into existence. However, the biblically and theologically superior account is that to be made in God’s image is to be given a particular vocation, a calling to represent—image—God in creation. Being God’s image is not a matter of what we are, but of God electing us to share in his life and work. God creates persons by natural, evolutionary means and then calls them into relationship with himself. The evaluation of hypotheses about how God created us should be guided by what God reveals about why he created us.

The Genesis story of God breathing the “breath of life” into the man-shaped being formed from the soil, i.e., the special creation of humans, cast in the vitalist framework of Ancient Near Eastern thought, reveals the special vocation humans have been given in God’s creation. God created this world with the aim of there being creatures like us, persons invited to share in God’s triune life. Special creation is properly understood in terms of God’s purposes in creating us, not the means by which he created us.

Traditional ways of understanding the Fall are undermined by the discovery of the evolutionary origins of human beings. It is not true that human beings were initially morally perfect but became morally imperfect. Our moral proclivities, good and bad, were present in rudimentary form in our pre-human ancestors. Instead, the figurative Genesis story of the Fall as an historical event points to the theologically vital fact that sin is not necessitated by human nature. Nor is it moral wrongdoing. Human beings are sinners: this means that our relationship with God is impaired by our unwillingness to trust him, and our willingness to usurp his place in the world. The truth of original sin is that we are bereft of God’s empirical presence, born into a world from which we have individually and collectively expelled God, who always intended to become incarnate as one of us. Because of our fallen condition, God incarnate is also our crucified and resurrected savior.