Verified by 
This post is the first of three looking at the implications of Darwin's theory of evolution for some of the most important topics in applied ethics, including suicide and euthanasia, and the proper treatment of nonhuman animals. These are controversial topics and you may well disagree with some of the ideas I'm going to float. I hope, though, that you'll at least find it interesting and perhaps that you'll find some food for thought in here.
First things first, a lot of people claim that evolutionary theory simply has no implications for any moral question. I suspect this view has been motivated in part by some of the unpopular and unpleasant conclusions that were drawn from the theory in the past. For instance, the Social Darwinists of the late 19th century and first half of the 20th century argued that giving aid to the weak, sick, and poor goes against nature - it undermines natural selection - and thus that it should be stopped. The vast majority of people reject this view now, and that includes the vast majority of evolutionists. But there have been some recent suggestions about other possible implications of evolutionary theory for ethics. One of the most important of these stems from the work of moral philosophers such as James Rachels and Peter Singer. According to these philosophers, in the wake of evolutionary theory, we must rethink or recalibrate our ethical commitments. Specifically, we must rethink the value we place on the lives of human beings vs. other animals.
Rachels identified an important trend in traditional Western moral thinking, which he dubbed the doctrine of human dignity. (Peter Singer uses the phrase sanctity of human life to refer to essentially the same thing.) Although the doctrine of human dignity is often not explicitly expressed, it is the heart and soul of the Western moral system, and provides the moorings for traditional morality.
The doctrine has two parts; the first pertains to humans, the second to nonhuman animals. The part pertaining to humans is the idea that human life has supreme worth - according to some, it has literally infinite value. A corollary of this view is that any activity that involves taking a human life (or at least an innocent human life) is utterly forbidden. This includes suicide, euthanasia, and abortion.
The flipside of the doctrine of human dignity concerns nonhuman animals. According to the doctrine, the lives of nonhuman animals have vastly less value than human lives. In fact, according to some commentators, such as the German enlightenment philosopher Immanuel Kant, they have no intrinsic value whatsoever. This means that, although it would be wrong for someone to torture your cat (sorry to put that image in your head), this is not because the cat wouldn't like it; it is only because you wouldn't like it. Animals have no intrinsic value; they exist for our benefit and may be sacrificed for our purposes.
Evolutionary theory does not directly contradict the doctrine of human dignity. It does something else, though: It undermines the foundations upon which it rests, and the worldview within which it makes any sense. I'll explain how. The doctrine of human dignity is supported by two main ideological pillars: the image-of-God thesis and the rationality thesis. The image-of-God thesis is the idea that we and we alone were created in the image of God and have an immortal soul, and that this is a fundamental difference between all humans and all other animals that justifies a fundamental difference in how we treat all humans vs. all other animals. The rationality thesis is the idea that we and we alone possess rationality - the spark of reason - and that this is the difference that justifies privileging members of our species above all others.
Evolutionary theory undermines both these theses. Let's start with the idea that we are made in the image of God. This is a problematic position after Darwin, even for those who still believe (or half-believe) in God. Given that the raw materials with which natural selection works are a product of random mutations and the random recombination of genes during sexual reproduction, and given also that evolutionary history is shaped by completely unpredictable events (like asteroids smashing into the planet, which is what wiped out the dinosaurs) - given these facts and the sheer randomness inherent in evolution, it becomes very difficult to believe that human beings were created in the image of God or in accordance with any pre-existing design. This undermines the image-of-God thesis.
Next, let's consider the rationality thesis: the idea that we are distinguished in some morally significant way from other animals by our possession of rationality. We now know that the ability to reason - the ability to work things out about the world - is not found only in humans. Certainly, we have a bigger helping of it than any other animal; however, it is clear that reason is distributed in differing degrees throughout the animal kingdom, and thus that the difference between us and other animals is one of degree rather than of kind. If people possess full rationality, then other apes and other animals possess at least partial rationality. (Note that it is easy to conceive of a more rational evolved being than Homo sapiens, and in relation to that being, we ourselves would only be partially rational.) So even if rationality did confer moral worth, we would still have no justification for allocating moral worth to all human beings but not to any other animal. We'd have to agree that some humans are more morally worthy than others because some are more rational than others, and that some nonhumans have some degree of moral worth.
There's a deeper problem, though. Even if we really were the only animal possessing rationality, it wouldn't matter because, from an evolutionary perspective, the capacity for reason is simply one adaptation among many millions that have evolved in the animal kingdom. We like to think that reason is the supreme adaptation; that rational animals deserve preferential treatment; and that nonhumans, because they don't have reason, have no intrinsic moral value. However, after Darwin, this is no different than, say, an elephant thinking that trunks are the supreme adaptation; that animals with trunks deserve preferential treatment; and that non-elephants, because they don't have trunks, have no intrinsic moral value. If we came across this view, we'd instantly dismiss it as an elephant-biased view of the world. However, the idea that reason is the supreme adaptation is an equally human-biased or anthropocentric view of the world. This undermines the rationality thesis.
By undermining both the rationality thesis and the image-of-God thesis, the Darwinian worldview undermines the doctrine of human dignity. It leaves it without intellectual foundations. This has important implications for many key issues in ethics. The idea that human life, and human life alone, is infinitely valuable has impregnated the ethical systems of the world, especially those of the West. Although the doctrine of human dignity has its origins in the religious conception of humankind, it has woven its tendrils into our secular codes of ethics. It is implicit in the ethical beliefs of many who doubt or even reject the various religious accounts of human origins, and who believe that right and wrong exist independently of religion. Thus, even though we in the West live in a semi-post-Christian world, in which the image-of-God thesis and the rationality thesis are widely dismissed, the ethical attitudes they inspired linger on. But what happens to these attitudes when we really get to grips with the fact that the foundations of our traditional morality have eroded? This is the question I'll address in my next few posts. In the next, I'll discuss the contentious topics of suicide and euthanasia.
-This post is excerpted, with changes, from the book Darwin, God and the Meaning of Life by Steve Stewart-Williams - available now from Amazon.com, Amazon.ca, and Amazon.uk.
