Why should we protect nature at all? The answers people give tend to fall into two broad families, and the difference between them runs through the whole of environmental ethics.

Two kinds of value

Something has instrumental value when it is valuable as a means to something else. Money is the classic example: it matters because of what it can buy. Something has intrinsic value when it is valuable in itself, as an end, whatever else it leads to. Most people think a human life has intrinsic value.

Nature clearly has instrumental value. Forests provide timber, rivers provide water, and wild plants have supplied many medicines. Scientists also speak of ecosystem services, the benefits people receive from working natural systems, such as bees pollinating crops, wetlands filtering water and soil storing carbon. Nature also has aesthetic, scientific, recreational and spiritual value for people. The question is whether it has value beyond all this.

Anthropocentrism

Anthropocentrism (from the Greek anthropos, human) is the view that only human beings have intrinsic value or full moral status; the rest of nature matters because of what it means for people. This is not necessarily an anti-environmental view. Philosophers distinguish a crude version, which counts only immediate wants such as profit, from enlightened or weak anthropocentrism, which takes seriously people's long-term interests, including those of future generations, and their deeper values, such as beauty and wonder. An enlightened anthropocentrist can defend strong protection for wild places.

Defenders say anthropocentrism is honest about where values come from, avoids the puzzle of how a swamp could have interests, and already gives plenty of reasons to protect nature.

Non-anthropocentrism

Non-anthropocentric views hold that at least some non-human beings or natural things have value in themselves. Different versions place that value in sentient animals (Level 3), in all living things, or in species and ecosystems (Level 4). Defenders argue that anthropocentrism resembles older prejudices that counted only one's own group, and that it leaves nature unprotected whenever destroying it happens to benefit people.

The philosopher Bryan Norton proposed the convergence hypothesis: in practice, enlightened anthropocentric and non-anthropocentric views will usually recommend similar policies, so environmentalists need not settle the theoretical dispute before working together. Critics reply that the two views come apart in hard cases.

Lynn White's thesis

In 1967 the American historian Lynn White Jr. published a short essay in the journal Science, “The Historical Roots of Our Ecologic Crisis,” that became one of the most debated texts in the field. In paraphrase, he argued that Western Christianity, especially in its medieval Latin form, taught that humans were set apart from nature and given dominion over it, and that this attitude helped make possible the exploitation of nature by Western science and technology. Because the roots of the problem were partly religious, he concluded, the remedy would have to be partly religious too. He proposed St. Francis of Assisi, who preached to birds and spoke of creatures as brothers and sisters, as a patron saint for ecologists. White was himself a churchgoing Christian.

White's critics

• Many theologians argued that White misread the Bible. Genesis also tells the first humans to “dress it and to keep it” (Genesis 2:15), and they developed a stewardship reading: humans are caretakers responsible for creation, not its owners.
• Historians pointed out that societies with very different religions, in ancient China, the Mediterranean and elsewhere, also cleared forests, overgrazed land and drove species to extinction.
• Others stressed economic forces, population growth and technology as larger causes than religious ideas.

Even critics found White's essay valuable: it showed that deep beliefs about humanity's place in nature shape how people treat the land.

Worked example: saving an obscure beetle

Imagine a small, dull-brown beetle that lives only in one stretch of old forest. A logging company wants to harvest the trees. The beetle has no known commercial use, and few people have ever seen it. Should the forest be protected for its sake?

A crude anthropocentrist would say no: the beetle does nothing for us, and the timber does.

An enlightened anthropocentrist has more to say. The beetle may play a role in the forest we do not yet understand, such as breaking down dead wood that returns nutrients to the soil. Species with no known use have later turned out to matter for medicine or research. The old forest also stores carbon, protects a watershed and is valued by hikers and future generations. Extinction is irreversible, so caution is wise. These are all reasons about human interests, yet they may be enough to protect the forest.

A non-anthropocentrist adds a different kind of reason: the beetle, or the species it belongs to, has value in itself. Even if every human benefit vanished, wiping it out would be a loss.

Notice the convergence hypothesis at work: both enlightened and non-anthropocentric thinkers might support protection. Now change the case. Suppose careful study shows the beetle has no ecological role and no research value, and the timber would fund a hospital. Here the views may split. The anthropocentrist leans toward logging; the non-anthropocentrist still counts the beetle's loss as a real cost to be weighed. Hard cases like this are where the theoretical difference shows.